# How to fireblock framing



## Termite

The whole idea behind fireblocking is to slow the progression of a fire in parts of the home you can't see, and to contain it to small areas of concealed space. If a fire in a stud wall can move vertically into the floor due to lack of a fireblock, the fire can compromise the structure much faster. If a fire in a wall or chase is able to move to the attic, the fire can quickly propogate. The idea of fireblocking is to use any number of materials and methods to keep that fire from moving in concealed vertical spaces to or from concealed horizontal spaces. The installation of those same materials serves double duty to minimize the ability of a fire to pull oxygen from other parts of the home. If it can't breathe, it can't burn.


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## AtlanticWBConst.

Good Topic for the site, and for "How-to".


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## Termite

The code allows you to use a few different materials for fireblocking. 3/4" plywood or OSB with edges blocked, 2x dimension lumber, two thicknesses of 1x lumber, 1/2" sheetrock, or rock wool or fiberglass unfaced insulation rigidly supported in place. Sheet metal is also widely accepted, although not mentioned in the code.


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## Termite

Now, a few scenarios...

This is one that just about every house has. Chases for HVAC vent pipes, plumbing and electrical must be firestopped top and bottom. This picture is not firestopped. See how the vertical chase is open to the horizontal spaces between the floor joists, which allows a fire to move from vertical to horizontal?


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## Termite

Two ways to deal with this. You can't put wood or insulation in contact with the vent (min 1" clearance), so sheet metal is one way most inspectors accept.

See how the metal was installed at the top of the vertical chase to prohibit vertical to horizontal movement? It is cut nice and tight to the vent and secured at the perimeter.

The way to deal with the first picture is to use 2x10 blocking between the joists at both sides of the chase to prevent the vertical to horizontal movement. In this picture the chase opens to the attic so that wasn't an option.


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## Termite

The same thing is required at the floor level to keep a fire from the floor joists from moving vertically into the chase, and vice-versa.
Sheet metal is the standard around here.


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## Termite

When you finish a basement, it is pretty standard to frame your walls out of 2x3's or 2x4's an inch or so away from the existing foundation or framed downwalls that sit on short foundation walls. This picture wasn't taken in a basement, but it clearly illustrates the gap left between the top plates of the walls. The gap between your basement top plate and the foundation will need to be firestopped. Options include very tightly packed fiberglass, wood, and fire foam for small gaps. I'll get into fire foam later.

This picture has not been firestopped yet. I'll definately get a lot of good pictures for finished basements down the road and go into them in depth here.


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## Termite

Here's a good example of firestopping basics. The studs, when sheetrocked, would be wide open to the attic since the rafters intersect the wall below the top plate. That allows fire to move freely between the wall and the attic.

They'll need to block between the studs with 2x4's just beneath the rafters.


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## Termite

This intersection between the rafters and the walls would have been fine but they added additional 2x's to the underside of the rafters to accommodate additional insulation thickness. The result is a gap left right underneath the top plate. 

The insulation will fill the gap, but doesn't comply with the code for this application.

See how they blocked that gap with the on-edge 2x4's right under the top plate? 

This is perfectly firestopped.


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## DangerMouse

as i'm doing a lot of this type construction here this spring, this is truly appreciated KC! 

tnkx!

DM


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## Termite

The following two pics are very similar situations. The first one has not been fireblocked. See how the studs open up to the attic? Gotta block that. The easiest way is to block between the studs below the opening to the attic. Another way would be to sheet the back side of the opening from the attic using 3/4" ply or sheetrock.

The second pic has been effectively fireblocked.


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## Termite

Let's talk plumbing and electric (and other) penetrations of top and bottom plates. 

Fire foam is a great way to deal with this. Not regular "Great Stuff", but specific fire foam. Great Stuff does make it, as do others. The annulus between the wood and the pipe or wire needs to be filled. Fire foam expands as it cures so it does a good job of filling the void. The code doesn't mention fire foam as an option but most inspectors will happily accept it since it is listed for the application. Most fire foam is listed to fill gaps up to 1-3/8", but that depends on the brand used.

Here's a pic of some plumbing properly firestopped through the bottom plate.









For larger holes, wood blocking or really tightly packed fiberglass is appropriate.


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## Termite

I'm out of pictures! Stay tuned, more to come...


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## gma2rjc

This is a great idea Nathan. KC, I'm glad to see this topic with the pictures. 

I've been working on sealing my attic since November and, depending on how you answer my question, I think it's completely sealed. In post #6, where the vent goes up through the attic floor, I had a heck of a time in my attic figuring out what to use to seal the 1" gap between the vent and the wood flooring because that vent gets pretty hot. First I used Great Stuff, then found out it can't be used on surfaces over 140 degrees F. I took all of that out and replaced it with the Great Stuff Fire Blocker foam. That can't be used on surfaces over 140 F either. I cut all of that out and I'm glad I did. The foam that was in contact with the vent was melted. I'll take a picture of a piece of it and post it. A couple nights ago I filled that gap with Rutland 500 degree F fire sealant. 

Will the fire sealant serve as a fireblock? Also, to put a piece of the sheet metal like you have around the vent in post #6, can it be done with an existing vent or only when the vent is being pieced together?


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## buletbob

Excellent presentation KC. BOB


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## Termite

gma2rjc said:


> This is a great idea Nathan. KC, I'm glad to see this topic with the pictures.
> 
> I've been working on sealing my attic since November and, depending on how you answer my question, I think it's completely sealed. In post #6, where the vent goes up through the attic floor, I had a heck of a time in my attic figuring out what to use to seal the 1" gap between the vent and the wood flooring because that vent gets pretty hot. First I used Great Stuff, then found out it can't be used on surfaces over 140 degrees F. I took all of that out and replaced it with the Great Stuff Fire Blocker foam. That can't be used on surfaces over 140 F either. I cut all of that out and I'm glad I did. The foam that was in contact with the vent was melted. I'll take a picture of a piece of it and post it. A couple nights ago I filled that gap with Rutland 500 degree F fire sealant.
> 
> Will the fire sealant serve as a fireblock? Also, to put a piece of the sheet metal like you have around the vent in post #6, can it be done with an existing vent or only when the vent is being pieced together?


Yup, you've got to maintain 1" clearance to type B gas vents. The Rutland sealant is a silicone-based RTV sealant for relatively low heat applications (500-600 degrees), but will work great for what you're using it for. It isn't a code-approved fireblock and isn't listed as such, although it will be much more effective than having nothing at all.

Normally a sheet metal pan is made as the pipe is being assembled so it can be slipped through. But that doesn't mean you can't make a two piece version and come at it from both sides of the pipe. The two halves can be screwed together with sheet metal screws and sealed tight with the RTV.


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## Termite

Ok, some more pictures. Finished basement...

This is a situation commonly encountered in basements of homes with truss floors, but the concept can be applied in many situations. The finished basement's stud wall's top plate is situated above the ceiling line. Once rocked, there's a pretty good-sized void between the ceiling and the top plate. 

You can see that the framer wisely placed flat 2x4 blocking horizontally just below the ceiling line. He may not have had fireblocks in mind as much as he was thinking about nailers for the sheetrock's top edge, but the blocks serve double duty.


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## Termite

This is pretty much the most common fireblocking issue in a finished basement. The wall is built tight to the underside of the floor joists and is rocked on only one side...


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## Termite

Buuuut, the challenge begins when the wall is furred out from the foundation wall (or framed downwall, whichever) a little bit, which most are.


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## Termite

Fire and oxygen can move freely behind the wall.

First, vertical to horizontal. The gap between the top plate and the foundation must be filled to seal the gap off. Wood is the best bet but often impractical. Fire foam is the easiest assuming the gap isn't too big. Some inspectors will allow tightly packed fiberglass insulation stuffed in the gap.

Second, horizontally. If a fire begins on one side of your basement wall you don't want it moving horizontally all the way across the basement to the other side. The code requires that you take steps to fireblock every 10' horizontally. This is accomplished by utilizing the stud to your advantage. Once again, foam, wood or packed insulation are good methods. 

This picture illustrates the potential fire movement that the code is concerned with.


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## Termite

So, here's where the firestopping goes.


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## Scuba_Dave

Good information

Question, if basement walls are put up only for insulation
No floor, no ceiling, is blocking still required?
I would think it should be, or would be a good idea
Since someone could come along later & put a ceiling in

Should the vertical blocking every 10' be sealed against the cement?
I was thinking a PT 2x would be good every 10' & provide more stability against pushing the wall towards the cement wall


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## Termite

ScubaDave, the answer to that is a little subjective...Tough call. I'd say that firestopping would not be required if there were no ceiling. Firestopping is only required for CONCEALED SPACES. If you can stand there and see fire pouring out the top of your wall (and so can the firefighters) I'd say that isn't a concealed space. It is worth considering that by framing walls you're making it very convenient to finish the basement, like you said. A good argument could be made for making the effort to firestop it now in case you (or a future owner) want to finish the ceiling down the road. 

The PT 2x is a great thought. That is how many people do it when the gap is significant. When it is a small gap, fire foam is hard to beat.


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## gma2rjc

KC - I guess I'm confused about the purpose of fire foam. For example, the Great Stuff Fire Blocker. It wasn't a good idea to use it for sealing around a hot vent that exceeds the foams temperature limit of 140 degrees F. How does it serve as a fire blocker if the heat and flames of a house fire exceed 140 F?


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## Termite

gma2rjc said:


> KC - I guess I'm confused about the purpose of fire foam. For example, the Great Stuff Fire Blocker. It wasn't a good idea to use it for sealing around a hot vent that exceeds the foams temperature limit of 140 degrees F. How does it serve as a fire blocker if the heat and flames of a house fire exceed 140 F?


Heck of a question, and I've been pondering it for years! *Fire will seek out a fuel source...In the case of a small concealed space, oxygen. The foam does a superb job of stopping air movement, which will certainly reduce the chance of a fire moving around*. Yes, if a flame hits it it'll fail. Great Stuff and other companies' products have to go through extensive certification and testing to be classified for firestopping or fireblocking, so I feel confident saying it will serve its intended purpose reasonably well. Is wood blocking or packed fiberglass or rock wool more fire resistant? Absolutely. *Like I mentioned earlier in this thread, it is always a good idea to check with the local building official before using fire foam, as the code does not list it as an approved fireblock but many building officials will approve it based on its listing.*


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## Termite

By the way, I errantly tend to interchange the words _fireblock_ and _firestop_. It is a bad habit I developed early in my career, and a lot of people do it so nobody really thinks anything of it in the field. This thread is about _fireblocking_. Firestopping is a whole other issue that really isn't encountered too much in single family residences. Firestopping is the act of sealing penetrations into and through fire-rated assemblies such as those in the floors and walls of apartment buildings and commercial structures.


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## DIY_JC

*fireblocking*

I am enjoying this thread... so thank you.

One issue I have (and many others do as well) with every house I have owned, is that the fireblocking also makes it near impossible to run wires (coax/speaker/cat5/6 etc) without tearing a house apart to get around/through the fireblocking. It wouldn't be an issue if the builders wired it for what people want/need but unfortunately, most do not. Even if they did, it would most likely be an issue in 5yrs when the technology changes. With that said, how does one circumvent the fireblocking while still providing the necessary protection? Is there a certain size hole that is allowed? Is that any different than the holes drilled for wiring the electrical?


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## Scuba_Dave

Good point
Can you install a PVC pipe & cap it & does that meet fireblock requirements??


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## Termite

DIY JC, you're right that fireblocking can add obstacles to running wires in dead spaces. That is one drawback, but it can usually be overcome. Drilling holes in the top and bottom plate of a concealed wall is pretty easy to do with a long flexible installers bit...Going horizontal is a challenge. Some homeowners and builders are wise enough to have the forethought to install "Murphy's law pipes" in the home to facilitate installation of wires from floor to floor years down the road. It can be challenging to run wires in a home with no firestopping at all, and hacking into the wall or ceiling can also be necessary. 

As for hole size relevant to firestopping, the code is silent. Any penetration through a framing member or block serving as a firestop has to be sealed up reasonably tight to prevent passage of air.

The good thing is that when fishing wires in an existing finished wall, it is impossible to firestop your holes, and nobody's going to fuss about it.

Balancing safety and convenience can often be a challenge when building! :yes:


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## Termite

Scuba_Dave said:


> Good point
> Can you install a PVC pipe & cap it & does that meet fireblock requirements??


You beat me to it. That's the Murphy's law pipe. Totally fine to do that. Very common in TV rooms with ceiling projectors or when audio/video components are in another area.


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## DIY_JC

I've thought of putting 3" pvc through the firestop... but honestly, I wouldn't want to cap it. If I cap'd it, then I would have to tear the walls apart again next time I added/changed cables. Obviously, that would defeat the firestop. Slightly better I suppose would be to stuff fiberglass into the pvc, perhaps in addition to fire-caulk around the outside of the pipe. 

If you did cap it, do people drill a hole through the cap to allow the wires through?


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## Scuba_Dave

I was thinking that the caps would be in an area that would be accessible. IE basement to attic. For me I have a PVC pipe going from the basement to a knee wall area on the 2nd floor. I can then run wire to the Master bedroom, 2nd bedroom, or bathroom. The dormer on the back prevents easy access to the other 1/2 of the rooms. When I redo the kitchen I want to add a PVC access pipe for the addition


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## fireguy

Are you going to list the temperature requirements for various parts of the project, such as the temps around B vent, smoke pipe, chimenys? And the UL ratings such as E84? 

When you are done with this little project, are you going to do one on Fire Stopping? Especially in commercial jobs.


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## Termite

fireguy said:


> Are you going to list the temperature requirements for various parts of the project, such as the temps around B vent, smoke pipe, chimenys? And the UL ratings such as E84?
> 
> When you are done with this little project, are you going to do one on Fire Stopping? Especially in commercial jobs.


The fireblocking requirements I'm discussing here are based on R602.8 of the International Residential Code. ASTM E84 and UL 273 are surface burning tests that don't really come into play for this application because R602.8.1 specifically specifies the allowable materials for residential fireblocking (wood, plywood, sheetrock, etc). 

Clearances to gas vents, fireplace vents, and chimneys are often an issue with firestopping materials. I'll try to get pics to demonstrate that as this thread progresses. B-vent clearances have already been discussed. 

As for another thread on _firestopping_, I'd like to do one, but it really wouldn't be beneficial for most on this site since we're geared toward residential DIY. In this thread I do plan to eventually touch on intumescent caulk and its virtues in the garage to maintain the required fire membrane at penetrations.


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## RDS

Thank you for this, termite. I recently spent a lot of time puzzling over fireblocking guidelines for my DIY bath remodel, and what you've provided here is clearer than anything else I found.


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## Maintenance 6

gma2rjc said:


> KC - I guess I'm confused about the purpose of fire foam. For example, the Great Stuff Fire Blocker. It wasn't a good idea to use it for sealing around a hot vent that exceeds the foams temperature limit of 140 degrees F. How does it serve as a fire blocker if the heat and flames of a house fire exceed 140 F?


Firestop products work in one of two ways. Intumescence or endothermy. When an endothermic product is exposed to fire it develops an insulating char on the surface. The char protects the material beneath it from further attacks by fire. Foams are endothermic. The other method is by intumescence. In this method, when the firestop product is exposed to high heat, it expands to fill any gaps, thus preventing the spread of heat and smoke. Firestop caulks and sealants can be either endothermic or intumescent. If you were to expose a firestop product to relatively high heat under a non fire condition, it would activate the fire proofing properties and expend thier usefullness. Further, firestop products are formulated to activate and provide protection during a relatively short timespan. Continued exposure to a moderate amount of heat over a long timespan is not what they were designed for.


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## Termite

RDS said:


> Thank you for this, termite. I recently spent a lot of time puzzling over fireblocking guidelines for my DIY bath remodel, and what you've provided here is clearer than anything else I found.


No problemo. Glad it helped. Trust me, I see the puzzled looks that builders give me when faced with fireblocking, so your average DIYer doesn't have any idea what to do. 

Sometime soon I'll get some more pictures to get into further detail on various fireblocking situations.


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## Termite

Maintenance 6 said:


> Firestop products work in one of two ways. Intumescence or endothermy. When an endothermic product is exposed to fire it develops an insulating char on the surface. The char protects the material beneath it from further attacks by fire. Foams are endothermic. The other method is by intumescence. In this method, when the firestop product is exposed to high heat, it expands to fill any gaps, thus preventing the spread of heat and smoke. Firestop caulks and sealants can be either endothermic or intumescent. If you were to expose a firestop product to relatively high heat under a non fire condition, it would activate the fire proofing properties and expend thier usefullness. Further, firestop products are formulated to activate and provide protection during a relatively short timespan. Continued exposure to a moderate amount of heat over a long timespan is not what they were designed for.


Interesting. It is my understanding that intumescent products expland (or intumesce) when heated, providing an endothermic barrier. Although the fireblocking foams do posess limited endothermic properties, they're not on par with an intumescent product. That's why they are not listed for firestopping, just fireblocking. 

As far as firecaulks/fire sealants for firestopping go, there are intumescent products and non-intumescent products. The way I understand it, both perform endothermically to prevent the passage of fire for the listed time of the assembly, even only one expands.

I can tell you for sure that the fire foam doesn't do very well against a propane torch! :laughing:


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## ponch37300

Great write up Termit. Here is a link to the hilti site which has a great selection of firestopping products. I worked for a commercial construction company for a while and we used these all the time in hospitals. Mostly the fire caulk for penatrations. http://www.us.hilti.com/holus/modules/prcat/prca_navigation.jsp?OID=-18981


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## Termite

ponch37300 said:


> Great write up Termit. Here is a link to the hilti site which has a great selection of firestopping products. I worked for a commercial construction company for a while and we used these all the time in hospitals. Mostly the fire caulk for penatrations. http://www.us.hilti.com/holus/modules/prcat/prca_navigation.jsp?OID=-18981


Right on. Hilti is a prominent manufacturer of firestopping products. Specseal and 3M are also commonly used and specified. 

These are normally not used much in single family residential applications though, since they're for firestopping, not fireblocking. Plus, they're very expensive ($12/tube or more).


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## Maintenance 6

thekctermite said:


> Interesting. It is my understanding that intumescent products expland (or intumesce) when heated, providing an endothermic barrier.
> 
> 
> Although the fireblocking foams do posess limited endothermic properties, they're not on par with an intumescent product. That's why they are not listed for firestopping, just fireblocking.
> 
> 
> 
> As far as firecaulks/fire sealants for firestopping go, there are intumescent products and non-intumescent products. The way I understand it, both perform endothermically to prevent the passage of fire for the listed time of the assembly, even only one expands.
> 
> 
> 
> I can tell you for sure that the fire foam doesn't do very well against a propane torch! :laughing:


Termite......... you should know that isn't a proven scientific test method.:no:

Agreed. Most firestop products ultimately act as endothermics. During a fire, purely endothermic fire stop products, will remain in the same configuration as they were installed but char over for protection, while intumescent products will expand to fill voids. During a fire, a bundle of wires for example, sealed with an endothermic, such as foam will burn away leaving a hole for smoke and flame to pass through. The sealant has remained intact, but the penetrating item has burned away. The fire seal has ultimately failed. An Intumescent sealant will expand as the wires begin to burn away and close the space, blocking smoke and flame. I realize this may be getting a little too in depth for a DIY site. For what it's worth, 3M and Hilti both offer UL rated firestop systems that use foam.
For construction joints, foam is a good product. For pentrating items, particularly ones that can burn away, an intumescent sealant should be used.


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## Termite

Maintenance 6 said:


> Termite......... you should know that isn't a proven scientific test method.:no:


I'm all about doing ******* tests! :laughing:

Funny thing about intumescent material is that so many tradesmen that install the stuff have no idea how it works or what it does. It is always fun to hit a drop of it with the torch and watch them get all excited.


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## Termite

Ok, stopped and took some pics on my way home today. 

This one shows where the electician drilled through the top plate of a wall that will be sheetrocked on both sides. Those holes must be filled with fire foam or intumescent firecaulk.

The second pic shows a wire hole and a pipe in the top plate, both of which must also be sealed. In rated/commercial construction, you'd have to use intumescent firecaulk around the PVC because it will melt in a fire. That isn't necessary in single family residential homes though.


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## Termite

This shows a bottom plate with copper and PVC pipes penetrating it. Also need to fireblock these.

(by the way, the PVC pipe protection is inadequate...a larger plate will be required on both sides)


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## Termite

Here's one that every house has. The hole around a tub trap must be fireblocked since there can be a considerable amount of concealed space under a tub/tub deck, and that space is usually wide open to the adjoining walls' studs. These are typically packed with fiberglass.

Yeah, I noticed the cut joist too. :whistling2:


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## Termite

Everybody has to fireblock their holes in plates. Not just sparky. The cable guy, home audio, etc.


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## Termite

Remember I mentioned dead spaces behind walls or between walls, and how they've got to be vertically firestopped every 10'? Here's a PERFECT example of how that is done. See how they notched the 3/4" plywood to fit up between the top plates? You don't get work any cleaner than this.


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## Termite

Here's a dead space that they framed unconventionally to take care of the fireblocking. Instead of using 2x top plates they used 3/4" plywood as one big top plate for all the little walls. That took care of the fireblock with no extra effort, and it was probably really easy to frame.


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## Termite

Here's a basement furdown that hasn't been fireblocked yet. See how the studs are wide open to the furdown? The plumbing will really make this a challenge. Usually I'll have people make a best effort to fill the bulk of the gap with wood and have them use packed insulation in the remaining spaces. Sometimes a metal strap helps bridge the gaps to give you something to pack the insulation against. On the right stud space I'd have them put a horizontal 2x4 block under the horizontal pipe. The left side block might be able to be notched out for the pipe and foamed tight.


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## Termite

And now, some properly firesblocked furdowns...


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## Termite

Here's a great way to build furdowns using 3/4" plywood against the studs. Cut it the height of the furdown, nail to the studs, and frame right to it. Viola! Fireblocked.
This framer held it just above his 2x4 furdown ceiling joists, and did a 2x4 band at the bottom of the plywood.


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## Termite

Here's a manufactured fireplace and direct vent chimney. It hasn't been fireblocked yet. A fire could move up and then horizontally into the joists directly above. The 2nd floor decking and the adjacent joists can serve as firestops, so this is easily taken care of.


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## Termite

Using some 2x's or 3/4" ply, here's where to put the fireblocks...


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## Termite

Here's a gable end wall that intersects with the roof/ceiling vault. It hasn't been fireblocked yet. The studs and the rafter space are open to each other.


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## Termite

A lot of people ask if they have to fireblock holes drilled through the studs for horizontal runs of wires and pipes.

The answer is generally no, except the wall must be sealed off into 10' sections. So, every 10' the studs should be sealed up. Personally, I'd take the time to seal them all, but that isn't required.


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## Termite

Last but not least, the code requires that walls taller than 10' be fireblocked so the spaces between the studs don't exceed 10' in height. This also applies to dead spaces and chases, and spaces behind furred out walls. So if your wall is 14' high, you need a block at the 10' height, or somewhere between 4' and 10' off the floor.


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## Termite

Ok, I'm out of scenarios, and you're probably tired of reading them. We've pretty much covered everything I can think of that you'd encounter on the average addition, remodel, or basement finish. 

If anyone has questions don't hesitate to post them. Even better, post pictures with your questions to illustrate what you need to fireblock or demonstrating how you fireblocked it. Just be ready for my critique! :laughing:


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## gma2rjc

> I've been working on sealing my attic since November and, depending on how you answer my question, I think it's completely sealed. In post #6, where the vent goes up through the attic floor, I had a heck of a time in my attic figuring out what to use to seal the 1" gap between the vent and the wood flooring because that vent gets pretty hot. First I used Great Stuff, then found out it can't be used on surfaces over 140 degrees F. I took all of that out and replaced it with the Great Stuff Fire Blocker foam. That can't be used on surfaces over 140 F either. I cut all of that out and I'm glad I did. The foam that was in contact with the vent was melted. I'll take a picture of a piece of it and post it.


Here are a couple pieces of the foam removed from around that hot vent. You can see the rounded, darker orange area that was in contact with the pipe. The lighter shade of orange is what it's suppose to look like. 











> I can tell you for sure that the fire foam doesn't do very well against a propane torch! :laughing:


I'm going to start a fire in the firepit this weekend and hold the foam over it to see how it burns. I'll burn the regular Great Stuff and the Fire Blocker. Up-wind from it, of course. :whistling2:


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## Termite

gma2rjc said:


> I'm going to start a fire in the firepit this weekend and hold the foam over it to see how it burns. I'll burn the regular Great Stuff and the Fire Blocker.


I'm all about setting stuff on fire in the fire pit. If you can, post some pics of the before and after condition of each. Don't burn yourself. :wink:


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## Termite

I definately encourage those of you working on framing basements, etc to post fireblocking-related pictures or questions on this thread. The more pictures there are, the more people will learn about how to do it right. :thumbup:


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## Termite

Another thing I thought of...

If the stairs of a structure are compromised in a fire you may lose your only way of getting out of the structure. Or, you might fall through. Or, a firefighter might fall through. It is definately beneficial to keep fire out of the stairs. 

The concealed space between stair stringers must be fireblocked at the top and the bottom. More often than not, the framing method automatically takes care of the fireblock. Stairs often hang on a band joist or beam of some sort, which effectively keeps the opening between the stringers from being connected to the space between the floor joists. For instance, if you're framing with floor trusses you're hanging your stair on a truss that has openings. So, a fireblock would be required at the top of the stairs to prevent a floor fire from compromising the stairs. 

The bottom of the stairs is fireblocked automatically if the floor is sheathed with 3/4" sheathing. If there are any holes or gaps of any kind (wires, pipes, etc), fireblock them. 

Here's what we're aiming for...


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## Termite

When you have a wall adjacent to a set of stairs, you must prevent the wall studs from opening up into the concealed space under the stair. 

Sometimes stairs are framed unconventionally. That is the case with winder stairs or circular (not spiral) stairs. A conventional stringer usually isn't used. Instead, each wedge-shaped tread is supported by horizontal framing that is supported by studs in an adjacent wall. A block is needed in this circumstance. I find it easiest to locate the block in the wall instead of under the stair. A 2x4 block between the studs just under the concealed space under the tread (and often just above the tread, depending on the wall) does the trick. 

I'll work on getting a picture of this as soon as I can find one!


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## gma2rjc

In your picture in post #62, should the floor joists under the floor at the top of the stairs be enclosed/fireblocked so that a fire underneath couldn't weaken the floor right there? It seems like the stairway is being fireblocked, but not the floor at the top.


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## Termite

Strange as it may seem, a fire is allowed to move around in a floor system based on the code requirements (not that the fire really cares what the code says). Fire can generally move freely through horizontal elements of the building such as soffits, floor systems, etc. So Gma2rjc, the answer to your question is that the intent of a fireblock at the stair is to protect the stair. An added benefit of the fireblock at a stair (when needed) is that it keeps a fire in one floor from moving to another floor within the concealed space between the stringers.


----------



## Termite

Discussing floors makes me think of another thing. *Draftstopping*. Draftstopping does basically the same thing as firestopping, although the requirements are a little different.

Here's the issue:
Draftstopping is required in basically two scenarios.

First, open web floor trusses. Since the trusses are webbed members as opposed to solid like 2x10's or I-joists, a fire in the floor on one side of the house could have incredible amounts of oxygen to feed itself since it can pull air from the entire floor system. If the floor area exceeds 1000 square feet and it isn't broken up by solid members such as beams, draftstopping is required to partition them off. 

Second, framed dropped ceilings. It is common for basement ceilings to be dropped to allow space for HVAC, plumbing, and architectural features such as curved soffits. When these dropped ceilings exceed 1000 square feet, they must be partitioned off by draftstopping. So basically, no part of the concealed floor system should have non-partitioned portions that exceed 1000 square feet. Dropped grid-type ceilings with ceiling tiles do not require draftstopping. 

Draftstops pretty much work exactly like fireblocks, but the material requirements are lessened. You can use 1/2" wallboard or 3/8" plywood/OSB, whereas a fireblock requires a minimum 3/4" thickness of plywood/OSB. On a dropped ceiling it is often necessary to frame something to attach the draftstop to. On a truss floor the draftstop is normally applied to the side of a truss.

It makes sense to locate the draftstops so that they're as minimal as possible. Using features such as stair openings and beams to your advantage will really minimize the length of the required draftstops in most cases. It also pays to pick areas that have as few plumbing, HVAC, and electrical penetrations as possible...Those are no fun to cut around when placing a draftstop.

If you're finishing what was an unfinished basement with trusses or a framed/sheetrocked dropped ceiling, your house didn't have draftstops and didn't need them until now. That's because the floor system wasn't concealed until you decided to conceal it. _*As with fireblocking, draftstopping is only required in concealed spaces*_. So now that you're concealing the ceiling, plan on draftstopping if there are 1000 square foot sections of uninterrupted floor.


----------



## Termite

I doctored a picture from earilier in the thread to illustrate how a draftstop would be applied in a truss floor system.


----------



## nap

not that is necessarily means anything coming from me, but;

I'm impressed KC. You put on a great demo via this forum (I realize how tough it can be) and you have shown yourself to be very knowledgeable on the subject at hand.


great job


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## gma2rjc

Well said, nap.


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## Termite

Thanks for saying so Nap. Much appreciated. Hopefully it helps somebody out and saves them from failing an inspection!


----------



## nap

thekctermite said:


> Thanks for saying so Nap. Much appreciated. Hopefully it helps somebody out and saves them from failing an inspection!


Actually, the inspection, to me, is secondary to the real reason fireblocking should be done properly and that is;

to prevent the spread of a fire so as to save as much of the building as possible and to save lives.


----------



## Termite

Absolutely! :thumbsup:


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## gma2rjc

Are there materials available on the market to build a house that is almost fire-proof? For example, foundations are already made of cement, but what about above-grade and second-story walls, second-story floors, etc.?


----------



## Termite

gma2rjc said:


> Are there materials available on the market to build a house that is almost fire-proof? For example, foundations are already made of cement, but what about above-grade and second-story walls, second-story floors, etc.?


There definately are, although costs make it largely prohibitive. 

First, fire retardant treated lumber is available and widely used in commercial construction. It is southern yellow pine that is treated with chemicals that essentially render it fireproof. Dimensional lumber and plywood is available with this treatment. Here is the website of one manufacturer: http://www.frtw.com/

You can even get fire retardant treated lumber with an exterior treatment for use on decks, pergolas, etc.......... (it isn't beautiful).

When talking about non-combustible residential construction, a lot of people instantly jump in the corner of light gauge steel framing (steel studs, steel joists, steel roof trusses). Although steel has its attributes, I think that is a mistake. The benefit of steel is that it won't contribute fuel to a fire, a fire has a hard time spreading in concealed spaces, and fireblocking is not required if the home is built completely noncombustible. However, homes are full of fuel whether their construction is combustible or not. If the carpet, furniture or stored items catch on fire, _the heat from a fire will compromise the steel building's structural integrity in very short order_ because the light gauge steel quickly softens. A wood structure may burn like crazy, but won't completely lose its structural integrity right away because it takes time for the wood members to burn through. 









C-channel light gauge steel joists.

There are some spray-on chemicals that will make combustible products fire-resistant (such as furniture, wood, drapes, etc), but that's a topic for another thread.


----------



## Wildie

While on the subject of stairs, as an owner of a rental property, I was required to install 5/8" drywall on the underside of the grade landing! It was a provincial regulation! The intent was prevent evacuees and firemen from falling through the floor, should fire occur underneath. I thought that this was a good idea and mention this as an adjunct to your post about fire blocking a staircase!


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## Termite

Wildie is correct. Although it is a structure protection issue more than fireblocking, any accessible area underneath a stair in an otherwise finished area is required to be sheetrocked. If the area under the stairs is not accessible, not rock is required by the code. In a fire it is good for the stairs to remain intact as long as possible.


----------



## gma2rjc

> Quote:
> Originally Posted by *gma2rjc*
> _I'm going to start a fire in the firepit this weekend and hold the foam over it to see how it burns. I'll burn the regular Great Stuff and the Fire Blocker._
> 
> Quote: Originally Posted By *thekctermite*
> I'm all about setting stuff on fire in the fire pit. If you can, post some pics of the before and after condition of each. Don't burn yourself. :wink:


 

On the left is 'Great Stuff' FireBlocking foam. On the right is 'Great Stuff' Gaps & Cracks. 



















The FireBlocker burns close to the same rate as the regular foam. They both give off strong-smelling black smoke. 

Sorry the pics are so dark, I couldn't get the flash to work on the camera because of the brightness of the snow.


----------



## Termite

That makes me hungry for smores. 

I figured that the fireblocking foam would perform a little better. :huh: There is probably a more scientific basis for comparison between the two...Perhaps having to do with ignition point, time frame from ignition to failure, heat transfer past the fireblock, flamespread, smoke developed, etc.


----------



## Termite

Since this thread is evolving into all sorts of fire protection related issues in single family homes (draftstopping, sheetrock, etc), I'm going to go ahead and cover other fire-protection topics people may encounter during a remodel or addition.


----------



## Termite

First off...Gypsum wallboard, or "sheetrock" as we all know it....

Why use sheetrock in a home as opposed to another material? I'll describe how it works, and why it has a real advantage over other matierials in a fire. 

Sheetrock is generally noncombustible. But that isn't all of what makes it good for preventing fire from getting from your garage, for instance, into your home. Sheetrock's biggest function in a fire is to resist the transfer of heat to the framing members that it protects. 

If you ever lift sheetrock, you know it is heavy. A lot of that weight is derived from the gypsum's moisture content. It contains about 21% water by weight. Amazing, huh? 

When heated by a fire, the water is slowly released in the form of steam, which serves as a thermal barrier to retard the transfer of heat. This process is called calcination. The Gypsum Association's manual gives a good analogy to help understand this. If you hold a block of ice in your hand, and use a blowtorch on the other side, your hand doesn't feel any heat. The calcination process is finished when the gypsum is devoid of moisture. Even when the moisture is gone, the sheetrock's mass and noncombustible properties continue to protect the structure from direct ignition from flames for a limited period of time as heat transfer through the gypsum increases. After enough heat exposure and heat increase, the wood framing members ignite and/or the steel structural members begin to soften and lose strength.


----------



## Termite

The only room you're absolutely required to sheetrock in your house is the garage. That will change in future code cycles, but we'll deal with current code here.

Lots of house fires originate in the garage. Fuel vapors, cars, lawnmowers, and other flammables are often stored in the garage. The code requires that the residence and its attic area be protected from the garage by 1/2" sheetrock on the walls. If there is habitable space above the garage, the ceiling must be rocked with 5/8" type X. Any structural elements (steel or wood posts, steel or wood beams, exterior walls, etc) that support the structure above must also be protected by 1/2" rock. 

Openings from the garage into the protected spaces of the residence must be equipped with 1-3/8" thick solid wood or honeycombed steel doors, or 20 minute rated fire doors. Most inspectors interpret this to also include attic access holes or drop down attic stairs in the garage....Neither are a good idea in a garage space. 

Ducts that pass through the garage must be 26 gauge. HVAC openings are not permitted in the garage. Although the code makes no allowance for them, I'll approve HVAC vents in the garage if UL listed 1 hour fire dampers are used and properly installed. Under no circumstance would I allow a return air vent opening in a garage. 

Installations of a number of things can compromise the integrity of the fire membrane that is required in the garage, and would easily allow passage of flame or heat in a garage fire. Electrical, for one. The building code prohibits installation of electrical boxes in fire membranes is the hole they create exceeds 16 square inches (2-gang box). Electrical panels recessed in the garage sheetrock violate this code, as do can lights, as do mudrings that are commonly used for garage openers, speakers, alarms, and central vac's. What's the point of going to the trouble of installing 5/8" type X rock in the ceiling and then punching ten 6" holes in it for can lights that won't even slow a fire down?


----------



## Maintenance 6

thekctermite said:


> That makes me hungry for smores.
> 
> I figured that the fireblocking foam would perform a little better. :huh: There is probably a more scientific basis for comparison between the two...Perhaps having to do with ignition point, time frame from ignition to failure, heat transfer past the fireblock, flamespread, smoke developed, etc.


I'm really not too surprised. Great Stuff Fireblock meets UL1715, which is a flammability standard. Nowhere do they claim that it is fireproof. In order to work, it only needs to burn away at a rate slower than other materials around it. In other words, if you closed an opening through a wood framed wall with foam and subjected it to a fire, the wooden part of the wall would burn away at the same rate or faster than the foam. Therefore the foam did it's job, even though it too would burn away. Keeping in mind that it only has to perform long enough to pass the test. Nowhere have I come across any UL rated firestop systems using Great Stuff foam. There are about 30 for Hilti fire foam and a number for 3M, both of which are silicone based rather than urethane. Just as info, if you ever come across Great Stuff in a wall or floor where a fire rating is required by code, ask to see a copy of the UL firestop assembly system showing that it was tested. If it can't be produced, it should not pass inspection.


----------



## Termite

Maintenance 6 said:


> Nowhere have I come across any UL rated firestop systems using Great Stuff foam. There are about 30 for Hilti fire foam and a number for 3M, both of which are silicone based rather than urethane. Just as info, if you ever come across Great Stuff in a wall or floor where a fire rating is required by code, ask to see a copy of the UL firestop assembly system showing that it was tested. If it can't be produced, it should not pass inspection.


Just so everyone understands, fireSTOPPING is very rarely encountered in single family residences. It is common in townhomes, apartments, and commercial structures. As M6 stated, I've never seen a UL firestop listing that allows fire foam. Typically firestopping products such as intumescent caulk, collars, putty pads, etc are used for firestopping.

FireBLOCKING on the other hand is a perfect application for this type of foam, and that is exactly what it is listed for. Follow the manufacturer's guidelines regarding the maximum gap it can fill though.


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## Maintenance 6

thekctermite said:


> Just so everyone understands, fireSTOPPING is very rarely encountered in single family residences. It is common in townhomes, apartments, and commercial structures. As M6 stated, I've never seen a UL firestop listing that allows fire foam. Typically firestopping products such as intumescent caulk, collars, putty pads, etc are used for firestopping.
> 
> FireBLOCKING on the other hand is a perfect application for this type of foam, and that is exactly what it is listed for. Follow the manufacturer's guidelines regarding the maximum gap it can fill though.


Just to clarify. I'm not bashing Great Stuff fire blocking foam. It does everything it's supposed to do and is a good product for residential use. The point I was trying to make is that firestopping is a complex science and just because the material burns over a campfire doesn't mean that it won't do it's job in a real fire situation. And that anyone with a need for a true rated firestop system should look to other products (although not likely in a DIY setting). By the way. Good thread Termite. Excellent topic and illustrations. Probably one of the most misunderstood components of construction, by builders, homeowners and inspectors.


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## Termite

Maintenance 6 said:


> By the way. Good thread Termite. Excellent topic and illustrations. Probably one of the most misunderstood components of construction, by builders, homeowners and inspectors.


Thanks Maintenance 6. I agree, fireblocking and firestopping are more often than not completely misunderstood by the people installing them. 

More than once I've borrowed a plumber's turbotorch to heat up some intumescent firecaulk on a jobsite so the guy that is installing it (and has been installing it for years) can actually see what it does in a fire. It cracks me up to watch the amazed look on their faces as the caulk intumesces like crazy. Once someone gains an understanding of how the system they're installing performs in a fire, they can do a better job of installing it.


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## Maintenance 6

I am currently certified by 3M and had the opportunity to work with a 3M field rep several years ago to help develop some firestop systems that are now UL listed. A lot of money is invested in testing the systems and procedures that you illustrated, to prove that they will do what they are supposed to under actual conditions. I had the priveledge to witness a couple of UL tests and they are brutal. Everything tested must pass 100% in order to become accredited. Fireblocking and firestopping procedures aren't just a way to make more work for a framer or remodeller (or a DIYer). They are tested systems.............and they work.


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## awang13

*Fireblocking basement walls, steel studs*

Trying to decide between steel or wood studs in basement walls. I am putting in a grid style tiled drop ceiling. Here are the questions. Does a drop ceiling count as concealed space? If so, what the best way to fireblock between metal studs? The groove in c channel of the stud makes blocks difficult to make? Or is regular blocks and firefoam the way here?

What about behind the studs? In a basement remodel the studs can never go directly against the foundation wall. One thought I had was to lag a 2x4 horizonal at ceiling height. That way I'd have a nice surface to mate my fireblocks between the studs too. 

Any comments?


----------



## Termite

awang13 said:


> Trying to decide between steel or wood studs in basement walls. I am putting in a grid style tiled drop ceiling. Here are the questions. Does a drop ceiling count as concealed space? If so, what the best way to fireblock between metal studs? The groove in c channel of the stud makes blocks difficult to make? Or is regular blocks and firefoam the way here?
> 
> What about behind the studs? In a basement remodel the studs can never go directly against the foundation wall. One thought I had was to lag a 2x4 horizonal at ceiling height. That way I'd have a nice surface to mate my fireblocks between the studs too.
> 
> Any comments?


As for the grid ceiling, there are a couple interpretations because the code doesn't speak to it. Personally, I require fireblocks at the ceiling line on grid ceilings because the space above the ceiling is in fact concealed space. 

Blocking between metal studs is a challenge for sure. The pros make it look easy, somehow. Personally, I'd use 2x blocking and screw it in. The channels would have to be packed with fiberglass or rock wool. When using steel studs it is best to meet with your inspector ahead of time to make sure that your method will be acceptable to him/her.

Attaching a 2x4 to the wall to act as a fireblock would work ok, but if the foundation wall ever moves you'll regret doing it. Instead, I'd suggest fire foam or fiberglass (or rock wool) stuffed between the foundation wall and the back of the horizontal blocking you install at the ceiling line. Just as effective but less risk of cracking the new framed wall if the foundation moves 1/8". 

Another consideration with steel studs is that they have holes in them for wiring and pipes. Those holes must be blocked off every 10' horizontally, and any penetrations of the top track must also be blocked.


----------



## Kermie

<work completed>


----------



## Termite

Kermie said:


> Now to the question: I have framed a wall similar to the above picture in front of the EPS Foamboard with a 1" gap.
> So basically at the top plate and vertically needs fireblocking? I will attach 1/2" drywall from the top plate to the sill fro the entire wall but how do I fireblock horizontally without disrupting the insulation/vapor barrier? (note: The framed wall will be completely stuffed with unfaced mineral wool for sound as well)


The foamboard complicates things, so I definately advise that you speak with your building inspector regarding how they want it fireblocked. 

In my opinion, the installation of mineral wool in the entire cavity will create a very effective fireblock. Provided all voids are filled, I wouldn't require anything else.


----------



## vetting

Fireblocking aside, is there a problem with insulation touching a heat duct?


----------



## Termite

vetting said:


> Fireblocking aside, is there a problem with insulation touching a heat duct?


A heat run, no. Not a problem. 

A flue...Big problem. Type B gas vents require a 1" airspace around them, and insulation cannot be piled against them.


----------



## n0c7

thekctermite said:


> Now, a few scenarios...
> 
> This is one that just about every house has. Chases for HVAC vent pipes, plumbing and electrical must be firestopped top and bottom. This picture is not firestopped. See how the vertical chase is open to the horizontal spaces between the floor joists, which allows a fire to move from vertical to horizontal?


Over here you can use fiberglass insulation around hot air ducts just not chimney(type-b vent). I've seen fiberglass shoved into spaces like the picture you posted. Not sure what type of vent that is but you don't want to give people the misconception that they cannot use insulation around ducts. For any electrical running over top or along side ducts, there needs to be insulation between them as well,ad least here in the great white north.

I don't believe firestopping is code(or just not enforced at all) where I'm from as this is the first I've heard of someone going to all of this effort(not to say I disagree with it). I don't believe we have to insulate our ceilings either regardless if its drop ceiling or drywalled. Last basement I finished only had the bedroom ceiling insulated for noise reduction, the rest of the place was drywalled with no insulation in the joists. Inspector did not care and never occured until I read your post that there was more to it. In the case of a ceiling being insulated and drywalled, would you recommend vapor barrier as well, mainly to help hold the insulation in place?


----------



## Termite

n0c7 said:


> Over here you can use fiberglass insulation around hot air ducts just not chimney(type-b vent). I've seen fiberglass shoved into spaces like the picture you posted. Not sure what type of vent that is but you don't want to give people the misconception that they cannot use insulation around ducts.


That was made very clear in post #92. As stated, you cannot insulate around chimneys or flues, but ductwork is fine.


----------



## tophercole

*Question Fireblock Ductwork*

thekctermite - Great Thread!!

Jsut found it yesterday. I was investigating how to do fireblocking 6 months ago and was dismayed how little there was posted online.

If I may take you up on the offer to post specific problems.

I am starting to finish my basement. Normally the wall is about 2 inches offset form the foundation wall. So I have put 5/8" fire rated sheetrock on the bottom of the joists, spanning from the foundation to the top 2x4 plate.

The issue is, I have an area that I was going to leave unfinished due to some ductwork dropping beneath the joists. This new wall will be 4 feet from the foundation wall. Now, Normally I assume, I could just throw a sheet of 5/8" up there so is no wall smoke could easily get up in the joist bays. But with all the duct work, it would be almost impossible. Would it be OK for this section just to stuff the joist bays with insulation. Maybe only the joist bays with the duct work in them? Again, can it jsu tbe unfaced batts or something else.

Sorry if I am unclear. 

I am trying to attach a picture of what I mean. Never attached a picture so I rescaled it. Hopefully you can still see it.


----------



## Wildie

n0c7 said:


> Over here you can use fiberglass insulation around hot air ducts just not chimney(type-b vent). I've seen fiberglass shoved into spaces like the picture you posted. Not sure what type of vent that is but you don't want to give people the misconception that they cannot use insulation around ducts. For any electrical running over top or along side ducts, there needs to be insulation between them as well,ad least here in the great white north.
> 
> I don't believe firestopping is code(or just not enforced at all) where I'm from as this is the first I've heard of someone going to all of this effort(not to say I disagree with it). I don't believe we have to insulate our ceilings either regardless if its drop ceiling or drywalled. Last basement I finished only had the bedroom ceiling insulated for noise reduction, the rest of the place was drywalled with no insulation in the joists. Inspector did not care and never occured until I read your post that there was more to it. In the case of a ceiling being insulated and drywalled, would you recommend vapor barrier as well, mainly to help hold the insulation in place?


 There's a popular TV show, HOLMES on HOMES recorded in Toronto, ON. One segment that I watched, Mike Holmes was building a rec room wall against the foundation wall.
He blocked off behind the headers with fire rated Roxul Insulation. Whether this is a code requirement in Ontario, I'm unsure. However, Mike always claims that he always builds better than what is required by code!

_ I don't think that ROXUL is distributed in the US._


----------



## n0c7

Wildie said:


> There's a popular TV show, HOLMES on HOMES recorded in Toronto, ON. One segment that I watched, Mike Holmes was building a rec room wall against the foundation wall.
> He blocked off behind the headers with fire rated Roxul Insulation. Whether this is a code requirement in Ontario, I'm unsure. However, Mike always claims that he always builds better than what is required by code!
> 
> _ I don't think that ROXUL is distributed in the US._


I'll watch out for that episode. I've been looking for any fireblocking code requirements for Alberta and have found nothing specifically. Ontario is politician capital of the country so and I've heard many rumors of how much stricter they are(including showing your passport to get into a bar.. ).


----------



## n0c7

thekctermite said:


> That was made very clear in post #92. As stated, you cannot insulate around chimneys or flues, but ductwork is fine.


Noticed that as soon as I posted. Sorry.


----------



## Wildie

n0c7 said:


> I'll watch out for that episode. I've been looking for any fireblocking code requirements for Alberta and have found nothing specifically. Ontario is politician capital of the country so and I've heard many rumors of how much stricter they are(including showing your passport to get into a bar.. ).


 Just if the bar is in Detroit! lol!


----------



## Termite

tophercole said:


> thekctermite - Great Thread!!
> 
> Jsut found it yesterday. I was investigating how to do fireblocking 6 months ago and was dismayed how little there was posted online.
> 
> If I may take you up on the offer to post specific problems.
> 
> I am starting to finish my basement. Normally the wall is about 2 inches offset form the foundation wall. So I have put 5/8" fire rated sheetrock on the bottom of the joists, spanning from the foundation to the top 2x4 plate.
> 
> The issue is, I have an area that I was going to leave unfinished due to some ductwork dropping beneath the joists. This new wall will be 4 feet from the foundation wall. Now, Normally I assume, I could just throw a sheet of 5/8" up there so is no wall smoke could easily get up in the joist bays. But with all the duct work, it would be almost impossible. Would it be OK for this section just to stuff the joist bays with insulation. Maybe only the joist bays with the duct work in them? Again, can it jsu tbe unfaced batts or something else.
> 
> Sorry if I am unclear.
> 
> I am trying to attach a picture of what I mean. Never attached a picture so I rescaled it. Hopefully you can still see it.


If the area is accessible and is not space concealed within the walls (a dead space more or less), fireblocking is not required. If there's a door to the area or if the area connects to another unfinished part of the basement then there's no need to rock.

If the space is concealed, it would be easier to fireblock between the joists above the wall's top plate. This can be done with 2x10 blocks, or smaller 2x blocks where things like pipes and ductwork get in the way. I'd recommend packing any remaining voids around the blocks with insulation.

Does that make sense?


----------



## tophercole

*fireblocking*

>>> 
Does that make sense?

It makes sense to me. The space will be accessible. i plan on using it as storage.

Worst case, the 2x10 blocking idea is simple enough. Thanks for your input. I appreciate it.


----------



## Termite

If you can walk into the room and look right at the framing, most people will agree that it is not concealed space and therefore does not require fireblocking.


----------



## Speedball

Page 4 Post #48

Fitting the plywood fire blocking as shown........Was this intended / specked as fire blocking or is this just a detailed carpenters work?

....fascinating pictures that bring a whole new idea to a framers mind.


----------



## Termite

Speedball said:


> Page 4 Post #48
> 
> Fitting the plywood fire blocking as shown........Was this intended / specked as fire blocking or is this just a detailed carpenters work?
> 
> ....fascinating pictures that bring a whole new idea to a framers mind.


Good question Speedball. Yes, that 3/4" plywood was installed as fireblocking because there are two separate walls there, through which horizontal fireblocking is required at 10' intervals. That particular framer was spot-on with his fireblocking and the work was among the cleanest I've ever seen. Take note of how he notched it between the top plates. Most builders would leave a gap there and fill it with insulation simply because its easier. You can tell that this guy prides himself in doing nice work.


----------



## Clutchcargo

thekctermite said:


> That makes me hungry for smores.
> 
> I figured that the fireblocking foam would perform a little better. :huh: There is probably a more scientific basis for comparison between the two...Perhaps having to do with ignition point, time frame from ignition to failure, heat transfer past the fireblock, flamespread, smoke developed, etc.


I read in Fine Homebuilding magazine that Great Stuff fireblocking foam was nothing more than Great Stuff Gaps and Cracks with an orange dye in it. 
My local building inspector told me to use the blue can Great Stuff (windows and doors) for fireblocking as it doesn't burn nearly as freely as the red can. 
I tested this by putting a torch to both products and he's right, I couldn't get the blue can foam to ignite but the red can product continued to burn on it's own.


----------



## Maintenance 6

The blue can does not have a UL rating. If the building inspector is telling you to use a product without a proper rating or UL listing in place of one that does, then he is setting himself up for a great deal of liability, regardless of what your torch test shows. Unscientific tailgate product tests performed by amatuer fire protection specialists don't hold up in court. Insurance companies love those. They can weasel out of a claim easier when a homeowner uses an untested, unrated product in place of the proper one. On the other hand, if you had a problem. you might be able to sue the inspector for having told you to use the wrong product.


----------



## Clutchcargo

That's a good point about the UL listing. The next time I see the inspector, I'm going to ask him about that.


----------



## Termite

Maintenance 6 is 100% right, your inspector is wrong in giving the option he's giving. Listings, my friend. Listings.


----------



## tjeieio

*Vertical blocking*

Okay - I have read this entire thread and have learned a great deal. Thanks for posting the excellent photos. One thing I have not fully understood is how to install the vertical @ 10' blocking. I have a 1" gap between my concrete basement wall and the 2x4 framing. If I stuff fiberglass insulation or rock wool behind one of the studs, how is that supposed to stay there? On the other hand, if I use P/T lumber or green sheetrock, how does this create a tight fit? Thanks in advance.


----------



## Termite

tjeieio said:


> Okay - I have read this entire thread and have learned a great deal. Thanks for posting the excellent photos. One thing I have not fully understood is how to install the vertical @ 10' blocking. I have a 1" gap between my concrete basement wall and the 2x4 framing. If I stuff fiberglass insulation or rock wool behind one of the studs, how is that supposed to stay there? On the other hand, if I use P/T lumber or green sheetrock, how does this create a tight fit? Thanks in advance.


You've got a couple options when doing this. 

The first is to use unfaced fiberglass insulation. Roll it up and pack it in very tight. When packed in it definitely won't go anywhere. Rock wool is pretty tough to pack in comparatively, unless you use something to retain it. In my experience most jurisdictions will allow fiberglass, since the code allows it in other fireblocking applications.

As you mentioned the other option is to use another piece of wood. Personally I wouldn't necessarily use treated material. Regular untreated 2x dimension lumber is fine, assuming it doesn't physically make contact with the concrete. Either wood you choose, there will be a bit of a gap...Perhaps less than 1/8". Such gaps MUST be sealed tight with orange fireblocking foam, which does a good job of bridging the gap.


----------



## tjeieio

*Fire blocking*

Thanks for the quick reply. It makes some sense now. Hopefully our building dept will okay the fiberglass use. Waiting for my plan review.


----------



## avshockey

*Fireblock Help*

I wish I would have stumbled upon this before I started to frame my basement. I have some questions on the best way to fireblock my basement. I had blanket insulation on my foundation walls. When I framed my perimeter walls, I failed to get the wall as tight as I would have liked to the blanket insulation. The result is anywhere from a .25 to 2 inch gap behind my studs and a gap behind the top plate. What would be the easiest method to fireblock this dead space? I was thinking of just buying thicker bat fiberglass insulation for between the studs to take up that extra space. Does that count for fireblock to stop fire from going vertical or horizontal? Or do I still need wood or insulation wedged in behind the top plate and behind a stud every 10' horizontally?
I also have a soffit and reading this thread I will need to 2X block between the studs to keep a fire from rolling from vertical to horizontal in the soffit. However, do I have to block the joist spaces where my soffit 
meets the ceiling (where the red X's are)?


----------



## tjeieio

*Fireblocking with insulation*

Turns out the city is requiring R-21 insulation in my perimeter walls, plus waterproofing. As such, the 1 inch gap will be filled tightly with the fiberglass batts (3 1/2" studs plus 1 inch = 4 1/2") since the batts are 5 1/2" thick. Telephone conversations suggest this will suffice for horizontal blocking. Vertical blocking will still require the insulation to be installed between floor joists and above the top plate.


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## Termite

Avshockey-

The joists above your soffit do not require fireblocking. You can insulate them if you wish though. Blocking the stud spaces from opening up into the soffit is required, as stated.

The gap between the foundation wall and the framed wall at the top plate is a judgement call. I would require that you pack the gap at the plateline with fiberglass. Simply using thicker batts fills the gap at the stud spaces but not behind the studs themselves. I'd suggest packing it with fiberglass just to be safe.


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## Termite

Jeez, nearly 16,200 views on this thread in less than 10 months. Glad you all are reading up on fireblocking! One of these days I'll get a chance to expand it a little bit with more info....:yes:


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## Gary in WA

Great job, Kc! I'm all for being safe, and hope more people read your posts. I use page #4: http://www.codecheck.com/cc/images/CC5thEdSample.pdf Your posts explain things a lot better for those not in the building trade using the "language".
Keep up the good work!

Be safe, Gary


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## 44070dart

*great info almost a little late ..maybe shoud be a sticky ?*

I also stumbled upon this and had to do some back tracking on my basement finishing project ...I'm not a carpenter by any means { mechanic by trade } but I can read and have used a good remodeling book to help my project along but fireblocking wasn't explained anywhere as well as this thread .. thank you kc for the time it took to post this :thumbup:


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## Termite

44070dart said:


> I also stumbled upon this and had to do some back tracking on my basement finishing project ...I'm not a carpenter by any means { mechanic by trade } but I can read and have used a good remodeling book to help my project along but fireblocking wasn't explained anywhere as well as this thread .. thank you kc for the time it took to post this :thumbup:


You're welcome! Glad it was of some help to you on your project.


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## ssmith147

Wow, am I glad I read this thread before proceeding with my basement finish. 

I have a question concerning soffits that I'm not sure has been answered, though (if it has, I apologize- there's a lot here).

I have to build soffit in my basemenbt around the HVAC, plumbing, gas line, and wiring. On one end of my basement the soffit will run up against the concrete, while on the other end it will drop down through the middle of the living space, butting up to the concrete on one end (clearance is not an issue).

I know the 2x stud cavities need to be fireblocked from the soffit. Do I need to fireblock the joists above? Using sheetrock/insulation/foam seems to be the only way to jigsaw the solution into place. It won'tbe impossible and I've already got some ideas on how to proceed with each challenge. Mostly, I want to put in the fireblocking and build the soffit underneath of it.


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## Termite

You don't have to isolate the horizontal soffit from the horizontal floor joists at all. You only have to isolate the vertical wall space from the horizontal soffit. Hope that makes sense!


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## ssmith147

That does make sense, and it was what I was hoping the answer was.

Thanks very much!


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## tjr002

*fire blocking a breaker panel*



thekctermite said:


> Ok, stopped and took some pics on my way home today.
> 
> This one shows where the electician drilled through the top plate of a wall that will be sheetrocked on both sides. Those holes must be filled with fire foam or intumescent firecaulk.
> 
> The second pic shows a wire hole and a pipe in the top plate, both of which must also be sealed. In rated/commercial construction, you'd have to use intumescent firecaulk around the PVC because it will melt in a fire. That isn't necessary in single family residential homes though.


Is it necessary to fireblock above the breaker panel in my basement? I want to enclose the breaker panel since it will be in a finished room. I was going to box around the panel and put an access panel on the front. Is that allowed? Is this considered a concealed space? How to I fireblock above the panel with all those wires coming out? Is it required? 
Thanks, Tom


----------



## Termite

tjr002 said:


> Is it necessary to fireblock above the breaker panel in my basement? I want to enclose the breaker panel since it will be in a finished room. I was going to box around the panel and put an access panel on the front. Is that allowed? Is this considered a concealed space? How to I fireblock above the panel with all those wires coming out? Is it required?
> Thanks, Tom


Sorry for the delayed response Tom. 

If your panel is located in a wall the wires that come out the top of the panel are likely passing through that wall's top plate. These plate penetrations are concealed and would need to be fireblocked. The top of the panel itself does not require fireblocking in any case that I can think of. Fire/oxygen/smoke can move vertically through the stud space (<10' vertical) without need for fireblocking.

If you're doing something different I'm having a hard time picturing what it might be. Anything other than what I described would be a subjective call that the inspector would have to address on a case by case basis.


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## tjr002

thekctermite said:


> Sorry for the delayed response Tom.
> 
> If your panel is located in a wall the wires that come out the top of the panel are likely passing through that wall's top plate. These plate penetrations are concealed and would need to be fireblocked. The top of the panel itself does not require fireblocking in any case that I can think of. Fire/oxygen/smoke can move vertically through the stud space (<10' vertical) without need for fireblocking.
> 
> If you're doing something different I'm having a hard time picturing what it might be. Anything other than what I described would be a subjective call that the inspector would have to address on a case by case basis.


The panel is just how you described. It is mounted to a board on the concrete basement wall. Below is NOT my panel setup, but is similar. I will be installing a top plate above the panel for my new wall. My dilema is how would you fireblock around all that wiring going up to the first floor? All the wiring will pass behind the top plate for my new wall and box I will be placing around the panel. How would you fireblock each wire that passes behind the top plate? Thanks. 

_*photo not available*_


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## nap

You use fire caulk where is passes through a fire rated assembly.


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## Termite

nap said:


> You use fire caulk where is passes through a fire rated assembly.


Very true, but not applicable in most single family dwellings. That's _firestopping_ and we're dealing with _fireblocking_. Duplexes, townhomes and apartments are more likely to contain rated assemblies. If your single family home is only a few feet from your neighbor's house you might have a rated assembly, but that is rare. The garage ceiling and walls of a single family home are fire membranes per-se, and many of us inspectors will require heat-vulnerable penetrations of that membrane to be sealed with intumescent firecaulk, which will help resist passage of fire if and when a PVC pipe, plastic water line or similar penetrating item disappears under the heat of a fire.

Firecaulk would be an awesome way to do it Tom, but it'll break the bank and is overkill. Plus you're likely to have some gaps that firecaulk just won't fill.

So you're framing a wall in line with your existing panel...
I'd suggest that once the wall is built you can do two things:

1) If the gap is not very large (1-3/8" or less) you can use _fireblocking foam _(not plain old spray foam) made by Great Stuff or other manufacturers. It comes out orange.

2) If the gap is larger or you're like me and you hate foam you can tightly pack the gaps with unfaced fiberglass insulation. Simply insulating the wall isn't enough. Pack the gaps tight. Rock wool would do equally well but is a bit more messy.

Do your best to minimize the size of the gaps by using wood blocking if you can.

Post pics of your wall once you frame it if you can, I'll try to check back.


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## tjr002

thekctermite said:


> Very true, but not applicable in most single family dwellings. That's _firestopping_ and we're dealing with _fireblocking_. Duplexes, townhomes and apartments are more likely to contain rated assemblies. If your single family home is only a few feet from your neighbor's house you might have a rated assembly, but that is rare.
> 
> Firecaulk would be an awesome way to do it Tom, but it'll break the bank and is overkill. Plus you're likely to have some gaps that firecaulk just won't fill.
> 
> So you're framing a wall in line with your existing panel...
> I'd suggest that once the wall is built you can do two things:
> 
> 1) If the gap is not very large (1-3/8" or less) you can use _fireblocking foam _(not plain old spray foam) made by Great Stuff or other manufacturers. It comes out orange.
> 
> 2) If the gap is larger or you're like me and you hate foam you can tightly pack the gaps with unfaced fiberglass insulation. Simply insulating the wall isn't enough. Pack the gaps tight. Rock wool would do equally well but is a bit more messy.
> 
> Do your best to minimize the size of the gaps by using wood blocking if you can.
> 
> Post pics of your wall once you frame it if you can, I'll try to check back.


 
Thanks! After looking at it again last night, using insulation is exactly what I was going to do. The gap will only be about an inch or so after I put up the top plate. I didn't realize that insulation is an acceptable fire blocking material. 
I'll get those picture up for you to look at. Thanks again!!!! :thumbsup:


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## Termite

Pretty much any inspector will/should accept tightly packed unfaced insulation based on (2003) IRC section R602.8 

_*Materials*: Batts or blankets of mineral wool or glass fiber or other approved material installed in such a manner as to be securely retained in place shall be permitted as an acceptable fireblock._
_*R602.8.1.1 Unfaced fiberglass* _
_....................When piping, conduit or similar obstructions are encountered, the insulaton shall be packed tightly around the obstruction_


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## barlav

Thank you for creating this thread. I'm about to start framing my basement and I knew that I had to fire block certain things but I didn't truly understand the concept. This has been the best resource I have found on this topic. This thread has explained very well the whys as well as the hows which I find very helpful. Having a firm grip on a concept behind something makes a big difference to me when actually implementing it. Thanks again!


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## Termite

No problem Barlav. I see a lot of builders and DIYers that have a real hard time with fireblocking on a daily basis. Glad the thread helped you out. Good luck on that basement! :thumbsup:


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## NE78FJ40

I posted this in building/construction, but maybe this would be better posted here. This is one of the requirements I'm dealing with. 

602.8 Fireblocking required: At all interconnections between concealed vertical and horizontal spaces such as occur at soffits, drop ceilings, and cove ceilings.

The inspector said I need to fireblock my soffits. I didn't totally understand where this needed to be done. In the pictures, where and how do I need to fireblock these soffits? He hasn't been out to my house yet to see how its been framed, but when I stopped by the inspection office he said this.


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## Termite

The inspector is talking about fireblocking the walls from the soffits. THERE IS NOTHING YOU HAVE TO DO WITH A SOFFIT THAT DOES NOT ABUT A VERTICAL WALL OR CHASE. So, the vertical stud spaces (or similar spaces) that would allow passage of oxygen or fire from the wall into the horizontal soffit need to be blocked off at or just below the ceiling line of the soffit. Your options from what I can discern from your pics are dimension lumber or unfaced fiberglass or mineral wool batts.

Remember, concealed spaces only! You do not have to fireblock in rooms that will not be sheetrocked or otherwise covered....Mechanical rooms or storage areas are often left unfinished and do not require fireblocking since the framing is not concealed.

If you review the early posts in this thread you'll see similar situations covered pretty thoroughly. Post #51 illustrates how to fireblock (with 2x dimension lumber) a soffit or furdown.


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## NE78FJ40

Thanks for the reply. It is beginning to make more sense now.


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## DIYHomeTheater

thekctermite said:


> If the area is accessible and is not space concealed within the walls (a dead space more or less), fireblocking is not required. If there's a door to the area or if the area connects to another unfinished part of the basement then there's no need to rock.


Why does the door make a difference?
Why are fire-blocking requirements restricted to 'concealed' spaces only? Is it not beneficial to block a fire in an 'unconcealed' space as well?

I am planning on building a basement wall that can't extend to a ceiling because of an HVAC duct prevents me from installing a top plate near the foundation wall. Please refer to attached schematic of proposed bulkhead. (The pink foil backed insulation is not a board, but rather a soft 'blanket' of 'pink stuff' low density mineral wool.) How would I fireblock this? Thank you


----------



## Termite

DIYHomeTheater said:


> Why does the door make a difference?
> It doesn't necessarily matter. The door discussion was pertinent to defining accessible space and the difference between concealed space and unconcealed space.
> 
> Why are fire-blocking requirements restricted to 'concealed' spaces only?
> Fire (and smoke and oxygen to fuel a fire) can move and propagate in concealed spaces without necessarily making themselves known to the building's occupants or firefighters. When the fire isn't contained within dead spaces, walls and floors, blocking open/exposed framing won't be effective.
> 
> Is it not beneficial to block a fire in an 'unconcealed' space as well?
> You can't in most cases. If you're in your home's unfinished mechanical room and a fire starts, that fire is visible. If you installed conventional blocking at platelines and vertical to horizontal transitions, the lack of sheetrock or other wallcovering will permit a fire to move right past that blocking.
> 
> However, you could do things such as install rock wool insulation in unfinished areas' framing members for an effective fireblock in those locations. It isn't required though. Everything hinges on "concealed".
> 
> I am planning on building a basement wall that can't extend to a ceiling because of an HVAC duct prevents me from installing a top plate near the foundation wall. Please refer to attached schematic of proposed bulkhead. How would I fireblock this? Thank you


Your fireblocking would need to occur at or below the "top plate" of the short wall that is built underneath the duct. That's where vertical stud spaces meet the horizontal bulkhead and the floor joists via the bulkhead. It will be necessary to pack insulation or fire foam between the insulation board and the top plate to prevent vertical movement.....Right about at the "N" in "concrete".

It can be argued that the foil backed foam insulation board shouldn't exist at the line of the fireblock because of its high flammability. In the event of a fire that stuff goes up like a Roman candle and will negate the benefit of the fireblocking because it acts like a wick that will permit passage of flame and smoke past your best fireblocking efforts. That's a jurisdictional decision, so I'd advise contacting your building inspector before you get carried away. Personally I require blocking solid to the foundation and they can install the foam board above and below the block as they see fit, but that's how I choose to enforce it....As a functional fireblock!


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## DIYHomeTheater

thekctermite said:


> Your fireblocking would need to occur at or below the "top plate" of the short wall that is built underneath the duct. That's where vertical stud spaces meet the horizontal bulkhead and the floor joists via the bulkhead. It will be necessary to pack insulation or fire foam between the insulation board and the top plate to prevent vertical movement.....Right about at the "N" in "concrete".
> 
> It can be argued that the foil backed foam insulation board shouldn't exist at the line of the fireblock because of its high flammability. In the event of a fire that stuff goes up like a Roman candle and will negate the benefit of the fireblocking because it acts like a wick that will permit passage of flame and smoke past your best fireblocking efforts. That's a jurisdictional decision, so I'd advise contacting your building inspector before you get carried away. Personally I require blocking solid to the foundation and they can install the foam board above and below the block as they see fit, but that's how I choose to enforce it....As a functional fireblock!


Thekctermite:
Thanks for your very helpful input. I apologize if some details were lacking from the picture. First, the insulation is not an 'insulation board' but rather R-13 foil backed 'mineral fiber' or 'glass wool' or 'fiber glass' type of material that is nailed to the concrete. It is a blanket of pink stuff that goes from the slab to the top of the foundation wall. Will this material be acceptable? This house was built new in 2006. The proposed wall is 21 feet long.

If I understand your intent, you do not advise the installation of styrofoam or other flammable boards. Point understood and acknowledged. 

Second, since the insulation is fluffy (like a blanket), I'd have to use mineral fiber to stuff between the existing insulation and the 'top plate' of the short wall, correct? Gypsum board will not be good enough because the insulation blanket does not form a perfect straight line to block completely and gypsum will still leave gaps. Alternately, I could put gypsum board and then stuff the gap with mineral fiber.

Third, how does one fire-block between the concealed horizontal spaces in the bulkhead/soffit and the concealed horizontal spaces (at 90 degree angles) between the floor joists?

Thanks, again


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## Termite

The insulation blanket if fine. Definitely not going to be a problem having that there. If you aren't building the wall tight to it, just use additional similar material to seal the gap between the insulation blanket and the top plate. Not sure what you mean regarding the gyp board, but want to be clear that you don't have to rock the back side of the wall on the foundation side. :no: Gyp can certainly be used as a fireblock though.

Your third question is pretty well covered in post 132. No fireblocking is required from the furdown/soffit/bulkhead to the floor system. Just have to fireblock the vertical walls from the bulkhead and the floor above. _Vertical to horizontal_ movement of a fire is what we're trying to prevent. Horizontal movement alone isn't an issue to the code.


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## Gary in WA

"Your third question is pretty well covered in post 132. No fireblocking is required from the furdown/soffit/bulkhead to the floor system. Just have to fireblock the vertical walls from the bulkhead and the floor above. _Vertical to horizontal_ movement of a fire is what we're trying to prevent. Horizontal movement alone isn't an issue to the code." ---------- Kc, aren't the *walls* behind the studs with a space to concrete filled with insulation batts required to be fire-stopped every 10' horizontally as well? Bottom plate to top plate between the concrete and the stud wall, every 10 lineal feet along the wall's length. 

http://www.codecheck.com/cc/images/CC5thEdSample.pdf

A side note to poster DHT--- http://www.buildingscience.com/documents/digests/bsd-103-understanding-basements?full_view=1
http://www.swinter.com/services/documents/ChallengesofBasementInsulation.pdf

Be safe, Gary


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## Jim F

Thanks for this thread KC. I had never heard of fireblocking before and am learning as I am reading through all these threads. I still did not give it much thought after reading the thread but now I am getting behind walls, under floors and into attic spaces as I modify and install new DWV and water supply lines. I see that my stud spaces are blocked with dimensional 2x4s and the holes I am creating for my new vent will also be sealed up when I am finished. 

I think it can be tempting as a homeowner to take shortcuts on safety codes after all, nobody can know what's going on in the privacy of your home unless you invite them in. But when you consider the safety of your family, it is not so tempting to cheap out on safety.


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## Termite

GBR in WA said:


> Kc, aren't the *walls* behind the studs with a space to concrete filled with insulation batts required to be fire-stopped every 10' horizontally as well? Bottom plate to top plate between the concrete and the stud wall, every 10 lineal feet along the wall's length.


Yes Gary. He does also have to fireblock the space between the foundation and the wall every 10' measured horizontally. It might work out that his wall is tight enough to the insulation blanket that is installed, negating the need for that fireblock. But the 10' horizontal thing has definitely been covered _somewhere_ back in this thread. :thumbsup:


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## Termite

Thanks Jim F. Thanks for saying thanks! I like your outlook on doing the job the correct and safest way. :yes:


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## tjr002

Thanks, for all your help as well. I just went through, and passed (horray!) my rough inspection in my basement for framing (fireblocking), plumbing, and electrical. Sadly, I felt all my work, and worry, was for nothing. "Did I do this right", "will this pass", "do I need to fireblock the soffits and electrical panel". The town inspector was at my home for a total of 2 minutes. He really didn't even look at any of my fireblocking. The electrical inspector on the other hand was VERY inpressed, and suprised that I even did any fireblocking. I suppose it depends from inspector to inspector. It was a good experience though. I learned about fireblocking (and what a mess and pain it can be) and just how important it really is. It gives me peace of mind that I have done something that will protect my family and make my home safer. They were also impressed that I placed smoke dectors in every room. I feel my family is worth it. Thanks again for all your advice. I'll get around to posting some pics soon.


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## Termite

tjr002 said:


> Thanks, for all your help as well. I just went through, and passed (horray!) my rough inspection in my basement for framing (fireblocking), plumbing, and electrical. Sadly, I felt all my work, and worry, was for nothing. "Did I do this right", "will this pass", "do I need to fireblock the soffits and electrical panel". The town inspector was at my home for a total of 2 minutes. He really didn't even look at any of my fireblocking. The electrical inspector on the other hand was VERY inpressed, and suprised that I even did any fireblocking. I suppose it depends from inspector to inspector. It was a good experience though. I learned about fireblocking (and what a mess and pain it can be) and just how important it really is. It gives me peace of mind that I have done something that will protect my family and make my home safer. They were also impressed that I placed smoke dectors in every room. I feel my family is worth it. Thanks again for all your advice. I'll get around to posting some pics soon.


_Don't want to get this thread off topic_, but I'm an inspector and I've been in your shoes and felt the same way with inspections done on my own home. My bathroom's final consisted of the guy checking to see if the sinks' traps leaked. Really? That's it? After we were done I told him what I do for a living. Awkward moment. :huh: 
I personally had to explain fireblocking to an inspector from another city when doing an inspection on his home in the city I worked in a few years ago. Not so impressive. It had to be pretty embarassing for that inspector to fail his own rough-in inspection. It goes to show you that inspectors are people too, some know their jobs better than others, and some care about what they do more than others.

There's a lot of satisfaction to be had in screwing that sheetrock to your wall knowing that everything behind that sheetrock is done correctly and as safely as possible. Well done! :thumbsup:


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## DIYHomeTheater

How does one fireblock if using clips to decouple walls from ceiling joists for sound proofing? See this product. I have no idea how to go about doing this.

Thanks


----------



## nap

DIYHomeTheater said:


> How does one fireblock if using clips to decouple walls from ceiling joists for sound proofing? See this product. I have no idea how to go about doing this.
> 
> Thanks


If a firewall is required at that point, decoupling is really a problem. You would have to run the sheetrock all the way up but obviously, that defeats the decoupling effect of the gadgets. There are methods to install a flexible joint using a fire rated caulk if you must have a firewall at that point.


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## Termite

DIYHomeTheater said:


> How does one fireblock if using clips to decouple walls from ceiling joists for sound proofing? See this product. I have no idea how to go about doing this.
> 
> Thanks


I agree with NAP *if* a firewall is required. That would rarely if ever be the case in single family residential construction, but is nearly always the case in multifamily, apartments, duplexes, condo's, etc. 

For the purposes of this thread, let's assume we're dealing with a basic house that doesn't have a firewall in it. If that isn't the case, start a thread and PM me the link and I'll try to help you out.

Those decoupling gadgets (soundproofing for those of you that aren't familiar) would conflict with the fireblocking requirements if they were used on the ceiling and fireblocking didn't occur. Assuming they're being mounted on the ceiling, the best bet is to run your walls' sheetrock all the way to the ceiling joists/top plate. That way there is no potential for vertical to horizontal fire movement from the wall to the dropped/decoupled ceiling. Edges can be sealed with acoustic sealants for a more finished look. 

If the walls were somehow decoupled and the ceiling were also decoupled from the framing, that presents a challenge. My best advice would be pre-rock the walls and ceiling before installing the decouplers or resilient channel. That is actually a common assembly for sound in multifamily construction and it works.


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## DIYHomeTheater

thekctermite said:


> Assuming they're being mounted on the ceiling, the best bet is to run your walls' sheetrock all the way to the ceiling joists/top plate. That way there is no potential for vertical to horizontal fire movement from the wall to the dropped/decoupled ceiling. Edges can be sealed with acoustic sealants for a more finished look.


Is it not standard practice to rock the ceilings before the walls? Will that work equally well? But, you still have to worry about blocking the concealed vertical spaces between studs or behind studs and the horizontal spaces between ceiling joists. How does one handle that? Thanks


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## DIYHomeTheater

I am going to frame my own interior basement walls. I have R-13 foil backed insulation ('pink stuff' fiberglass) attached to basement walls. My jurisdiction recommends the attached method for fireblocking.

My question is:

Is inserting 1/2" drywall between top plate of stud wall and ceiling (blocking or joists) strong enough? I am not sure if the stud wall may cause the drywall to crack. Also, the diagram shows that the continuous fireblocking drywall terminates roughly half-way through the width of the top plate. To me it sounds easier to simply extend it all the way to the inside edge of the top plate and then let it butt up against drywall that will be attached to the ceiling. Any thoughts? Thanks


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## DIYHomeTheater

thekctermite said:


> I agree with NAP *if* a firewall is required. That would rarely if ever be the case in single family residential construction, but is nearly always the case in multifamily, apartments, duplexes, condo's, etc.
> 
> For the purposes of this thread, let's assume we're dealing with a basic house that doesn't have a firewall in it. If that isn't the case, start a thread and PM me the link and I'll try to help you out.
> 
> Those decoupling gadgets (soundproofing for those of you that aren't familiar) would conflict with the fireblocking requirements if they were used on the ceiling and fireblocking didn't occur. Assuming they're being mounted on the ceiling, the best bet is to run your walls' sheetrock all the way to the ceiling joists/top plate. That way there is no potential for vertical to horizontal fire movement from the wall to the dropped/decoupled ceiling. Edges can be sealed with acoustic sealants for a more finished look.
> 
> If the walls were somehow decoupled and the ceiling were also decoupled from the framing, that presents a challenge. My best advice would be pre-rock the walls and ceiling before installing the decouplers or resilient channel. That is actually a common assembly for sound in multifamily construction and it works.


Would stuffing Roxul in the between the top plate and the ceiling joist do the trick?


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## Termite

DIYHomeTheater said:


> Would stuffing Roxul in the between the top plate and the ceiling joist do the trick?


If it is securely retained in place, yes. Insulation cannot be loosely placed to create a fireblock. I'd be looking for a large quantity of insulation to accept it as a fireblock in that application.


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## legende

Lurked Nov of last year but and actually started framing basement without permit. Now am worried about actually getting a permit. Actually I went to zoning office, obtained forms and requested for any zoning/coding materials and they say they don't distribute out any longer since not everything applies to a given property. Sounds kind of suspicious to me. Then how do I know if I'm actually doing the right thing or not. Is this what they mean by NJ corruption? Gentleman I spoke to actually suggested metal studs but I've already purchased 2x3 lumber. Anyway, do you think fireblocking I've done with 9/16 drywall on above top plate is sufficient so far or is this sloppy work? Live in Sayreville, NJ and this was a 2005 new construction with pre-installed foil batt insulation. New framing is offset from actual concrete wall(anywhere from 4-6" approx). Please note, of course, that in pictures wall is the one with foil backing. Let me know if I need to post individual pictures. Framing is 2x3" and 9/16 drywall as fireblock on above or beside top plate.
http://alegende.multiply.com/photos/album/6/basement


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## itsnotrequired

i've read through this thread and see a lot of discussion about vertical-to-horizontal fire blocks but what about horizontal-to-horizontal? i'm finishing a basement and will be putting in a wall between two rooms. wall is perpendicular to floor joists. wall is basic 2x4 with 1/2" drywall on both sides. ceilings in both rooms would be finished with 1/2" drywall. header for the new wall takes care of vertical-to-horizontal blocking but what about in the joist cavities shared above the two rooms? couldn't fire readily pass from one room to another in this case? would i need to put blocking in the floor joist cavities (i.e. "extending" the wall up to the first floor)?


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## jbatl

Hey termite (or any others)...

I kinda have one that is in between stages. I have read through a few times and feel like I have something that may be just beyond one of the other posts. My friends that have all finished their basements keep telling me that I am just putting up drywall and to stop worrying/analyzing. But, I know that I am doing more than that - I am creating a space that no one can see again.

My question is about the following wall (can't figure out how to post a pic - but here is a link to it)...

http://i798.photobucket.com/albums/yy264/jbatl/IMG_3253.jpg

On the other side of that wall is the garage. This is a utility room that I am now finishing to be an office (it will be conditioned). My question (obviously) is about fireblocking. You can see the back of the chase from the vertical space. This is a 2x6 wall with a 2x4 wall in front and a chase infront of that - I think there was an 'oops' in building and that is why I have that.

What do I do? I am going to want insulation in that wall. Will that be enough? If so, I guess I need to use unfaced (pretty packed in) and then put a barrier on the side I am going to rock. If I need to block, do I put insulation above, then block, then insulation below?
Any consideration to the circuit breaker that is about 3 stud bays over to the right of that picture...

Thanks to anyone/everyone for their time/opinion.
--JB


----------



## BrooklynDIY

This is the most amazing thread. I have frequently spent hours scratching my head wondering when I should be fireblocking and when I should not. You explain it easily and with pictures.

I currently live in a 150 year old 4 story brownstone. Running vertically (in a corner of the house) from the basement to the top floor is a pipe chase about 1 foot wide by 6 inches deep. 

The chase abuts against brick on two sides and framed drywall (or board depending on the floor) on the other two sides. From what I can tell, it is fireblocked from floor and ceiling as well as soffits (but of course I cant see every spot).

I live on the top two floors of the brownstone and am currently doing renovations in the area where this chase runs.

Any insights could be very helpful:

- Should I fireblock and insulate around the pipes as much as possible on the floor and ceiling of the room I am working in? If so with what (No way I'm going to be cutting pipes and fitting them through anything)?

- Are there requirements for placing access panels into the chase?


On another note...in the same room, which happens to be my kitchen, I there is a soffit that runs right above where the cabinets are located. The soffit is much larger than it needs to be and very poorly built. It contains the drainage for tub, sink and toilet on the floor above to the chase mentioned in the above sections.

I am considering tearing it out entirely (at least down to the required framing elements) and either rebuilding it or potentially even placing another set of cabinet framing and doors (it would fit exactly) that would make it appear that my cabinets ran all the way to the ceiling. So if I did that, from what I can tell, it sounds like I would not necessarily need any particular fireblock (since it only concerns a horrizontally running soffit against ceiling joists...).

I will attempt to get pictures of all of this or draw diiagrams, but any input would be helpful. I'm certain to spend countless hours thinking about this and slowing down any forward progress until I feel comfortable with how this should be executed.

Thanks,

BrooklynDIY


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## JordanRHughes

Awesome thread. Thanks for sharing. i am going to have to read this when I got more time. Thanks for the share.


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## Termite

Horizontal to horizontal fireblocking isn't required by code in the circumstance you're describing. You could block it off but there is no requirement to do so. 

Fireblocking isn't intended to keep fire from passing from one room to another. It is intended to keep fire from moving too far in concealed spaces, which makes fire hard to fight and hard to detect. 

Draftstopping is required in large concealed horizontal spaces such as furred down ceilings or open web trusses, but those spaces have to be pretty darn big before that requirement kicks in. Most homes aren't large enough to require it.



itsnotrequired said:


> i've read through this thread and see a lot of discussion about vertical-to-horizontal fire blocks but what about horizontal-to-horizontal? i'm finishing a basement and will be putting in a wall between two rooms. wall is perpendicular to floor joists. wall is basic 2x4 with 1/2" drywall on both sides. ceilings in both rooms would be finished with 1/2" drywall. header for the new wall takes care of vertical-to-horizontal blocking but what about in the joist cavities shared above the two rooms? couldn't fire readily pass from one room to another in this case? would i need to put blocking in the floor joist cavities (i.e. "extending" the wall up to the first floor)?


----------



## Termite

jbatl said:


> Hey termite (or any others)...
> 
> I kinda have one that is in between stages. I have read through a few times and feel like I have something that may be just beyond one of the other posts. My friends that have all finished their basements keep telling me that I am just putting up drywall and to stop worrying/analyzing. But, I know that I am doing more than that - I am creating a space that no one can see again.
> 
> My question is about the following wall (can't figure out how to post a pic - but here is a link to it)...
> 
> http://i798.photobucket.com/albums/yy264/jbatl/IMG_3253.jpg
> 
> On the other side of that wall is the garage. This is a utility room that I am now finishing to be an office (it will be conditioned). My question (obviously) is about fireblocking. You can see the back of the chase from the vertical space. This is a 2x6 wall with a 2x4 wall in front and a chase infront of that - I think there was an 'oops' in building and that is why I have that.
> 
> What do I do? I am going to want insulation in that wall. Will that be enough? If so, I guess I need to use unfaced (pretty packed in) and then put a barrier on the side I am going to rock. If I need to block, do I put insulation above, then block, then insulation below?
> Any consideration to the circuit breaker that is about 3 stud bays over to the right of that picture...
> 
> Thanks to anyone/everyone for their time/opinion.
> --JB


Sorry for the late response JB. Hope it isn't too late to help. I'm not fully understanding what you've got going on....Could you possibly post some more pictures to better paint a picture of the space?


----------



## Termite

BrooklynDIY said:


> This is the most amazing thread. I have frequently spent hours scratching my head wondering when I should be fireblocking and when I should not. You explain it easily and with pictures.
> 
> I currently live in a 150 year old 4 story brownstone. Running vertically (in a corner of the house) from the basement to the top floor is a pipe chase about 1 foot wide by 6 inches deep.
> 
> The chase abuts against brick on two sides and framed drywall (or board depending on the floor) on the other two sides. From what I can tell, it is fireblocked from floor and ceiling as well as soffits (but of course I cant see every spot).
> 
> I live on the top two floors of the brownstone and am currently doing renovations in the area where this chase runs.
> 
> Any insights could be very helpful:
> 
> - Should I fireblock and insulate around the pipes as much as possible on the floor and ceiling of the room I am working in? If so with what (No way I'm going to be cutting pipes and fitting them through anything)?
> Provided the chase is just a chase and isn't serving as a combustion air vent for fuel burning appliances in a basement, you should be able to fireblock it effectively.
> - Are there requirements for placing access panels into the chase?
> Not in the residential code. I'm assuming your building is just a unit or two and isn't covered under the commercial code. That is an assumption.
> 
> On another note...in the same room, which happens to be my kitchen, I there is a soffit that runs right above where the cabinets are located. The soffit is much larger than it needs to be and very poorly built. It contains the drainage for tub, sink and toilet on the floor above to the chase mentioned in the above sections.
> 
> I am considering tearing it out entirely (at least down to the required framing elements) and either rebuilding it or potentially even placing another set of cabinet framing and doors (it would fit exactly) that would make it appear that my cabinets ran all the way to the ceiling. So if I did that, from what I can tell, it sounds like I would not necessarily need any particular fireblock (since it only concerns a horrizontally running soffit against ceiling joists...).
> Assuming your soffit doesn't intersect open vertical wall framing, there is no requirement to isolate it from the ceiling joists above. If you can see into the studs, it would be a good idea to fireblock it before closing it up.
> 
> I will attempt to get pictures of all of this or draw diiagrams, but any input would be helpful. I'm certain to spend countless hours thinking about this and slowing down any forward progress until I feel comfortable with how this should be executed.
> 
> Thanks,
> 
> BrooklynDIY


Sorry for the late response BrooklynDIY, hope this helps.


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## BrooklynDIY

Thanks for the reply. Its only two units. I'm pretty certain that the chase is just that ... the furnace is on the other side of the house and has a chimney to vent out. 

With respect to fireblocking between the floors where the pipes go through in the chase (at floor and ceiling), what is the best material to do this with? Just get some fireproof insulation? Cover with sheetmetal as much as possible then caulk? 

The soffit does intersect with the chase, in the past it wasn't blocked from the vertical chase at all. I'll frame and drywall around the pipes as best as possible to cut off the chase from the soffit; however I'm wondering what the best way to fill in around the cracks that are left is? Apply drywall mud right up to the pipe, caulk?

Thanks!


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## legende

legende said:


> Lurked Nov of last year but and actually started framing basement without permit. Now am worried about actually getting a permit. Actually I went to zoning office, obtained forms and requested for any zoning/coding materials and they say they don't distribute out any longer since not everything applies to a given property. Sounds kind of suspicious to me. Then how do I know if I'm actually doing the right thing or not. Is this what they mean by NJ corruption? Gentleman I spoke to actually suggested metal studs but I've already purchased 2x3 lumber. Anyway, do you think fireblocking I've done with 9/16 drywall on above top plate is sufficient so far or is this sloppy work? Live in Sayreville, NJ and this was a 2005 new construction with pre-installed foil batt insulation. New framing is offset from actual concrete wall(anywhere from 4-6" approx). Please note, of course, that in pictures wall is the one with foil backing. Let me know if I need to post individual pictures. Framing is 2x3" and 9/16 drywall as fireblock on above or beside top plate.
> http://alegende.multiply.com/photos/album/6/basement



Sorry, but did anyone get a chance to look at these pictures? These are pictures of headers at the top of the ceiling. As you can see, there is already foil-backed insulation installed in this 5 year old house. It is also very difficult to install a 2x8 pressure treated firestop header as there is not enough room to wedge it between top of foil-backed insulation, the concrete wall slap and ceiling joists. I don't have a picture of this but trust me, this is reason why I went with the 5/8" sheetrock method as suggested by a Home Depot consultant. Anyway, do you suggest I redo this; maybe double the thickness, as well as the width of the drywall header so it will be over the frame header instead of beside it. 
Also, on picture #3, I left a hole in the drywall header since I need access to a pipe shutoff valve - should this be covered with just insulation or is there another way to do this and still keep the access to the valve?
Thanks in advance.


----------



## Termite

Legende, I looked at your pictures but honestly I can't make a bit of sense from them. They're too close to determine the subject area and they're taken at odd angles. Can you back up, take some overall pics of the area in question? I'm thinking there may be some info I could gain by seeing the entire wall and how it intersects the ceiling.

Also, can you please post your pics on this site as opposed to a hosting site. That way your pics are a permanent part of this thread. 3rd party hosting sites are discouraged just because a few months from now you may delete the pics from your album and they'll no longer be viewable to us. 

Post up some better pics and more info and I'll do my best to help you out. 

By the way, the "Home Depot *consultant*" phrase scares the bejeebers out of me. :laughing:


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## Weekend Worker

Fine Hombuilding and Mike Holmes both recommend basement remodels to be framed in this manner: Concrete wall>2 in foam board directly against concrete>sheet rock directly against foam board (cavities can be filled with insulation as an option). If your framed wall has a top plate, do you need any additional fire stop (other then sealing wire/pipe penetrations)? The article (ref. below) shows a plywood strip installed over the foam board blocking airflow into the ceiling joist. Based on a previous comment on page 10, do you recommend against using foam board?

Ref: http://www.blessthishouse.biz/content/00/01/58/40/76/userimages/Finishing%20A%20Basement.pdf


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## Termite

Weekend worker, this is where the code gets a little interpretive, so take this with a grain of salt...

I agree with the article you posted that shows a strip of plywood above any foam board, fixed to the underside of the floor joists or ceiling joists. That takes care of the required fireblock, provided the plywood is 3/4" thick. Some might argue that the foam blocks the airflow between the wall and the horizontal spaces above the wall, but I differ on that. _In a fire, that foam goes bye-bye really quick_. It is highly combustible and will not provide any barrier against fire or hot gases. So, on my inspections I require the space to be fireblocked with code-specified materials whether foam is used or not. It certainly isn't prohibited, but it isn't recognized or listed as a fireblocking material.

Personally I don't care to put foam in my walls. I agree with the insulative and moisture attributes that foam offers and recognize those benefits. So I guess I wouldn't go as far as recommending against it. Being safety minded, I don't want anything that combustible in my walls. It burns, and it burns fast. When burning it gives off mighty toxic fumes. I'm more of a vapor barrier and fiberglass guy I guess.


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## KoryLGriffin

Awesome thread. This is something we have to address in the house we just purchased. Thanks for sharing...

:thumbup:


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## legende

thekctermite said:


> Legende, I looked at your pictures but honestly I can't make a bit of sense from them. They're too close to determine the subject area and they're taken at odd angles. Can you back up, take some overall pics of the area in question? I'm thinking there may be some info I could gain by seeing the entire wall and how it intersects the ceiling.
> 
> Also, can you please post your pics on this site as opposed to a hosting site. That way your pics are a permanent part of this thread. 3rd party hosting sites are discouraged just because a few months from now you may delete the pics from your album and they'll no longer be viewable to us.
> 
> Post up some better pics and more info and I'll do my best to help you out.
> 
> By the way, the "Home Depot *consultant*" phrase scares the bejeebers out of me. :laughing:



Here's some pictures, hopefully they'll be posted on this site now. Excuse the HD consultant reference. Didn't know what to call the guy; guess just plain "guy" would be better. 

p.s. excuse the delay as well. went on a 2 week vac, then misplaced camera that had these pics.


----------



## legende

legende said:


> Lurked Nov of last year but and actually started framing basement without permit. Now am worried about actually getting a permit. Actually I went to zoning office, obtained forms and requested for any zoning/coding materials and they say they don't distribute out any longer since not everything applies to a given property. Sounds kind of suspicious to me. Then how do I know if I'm actually doing the right thing or not. Is this what they mean by NJ corruption? Gentleman I spoke to actually suggested metal studs but I've already purchased 2x3 lumber. Anyway, do you think fireblocking I've done with 9/16 drywall on above top plate is sufficient so far or is this sloppy work? Live in Sayreville, NJ and this was a 2005 new construction with pre-installed foil batt insulation. New framing is offset from actual concrete wall(anywhere from 4-6" approx). Please note, of course, that in pictures wall is the one with foil backing. Let me know if I need to post individual pictures. Framing is 2x3" and 9/16 drywall as fireblock on above or beside top plate.
> http://alegende.multiply.com/photos/album/6/basement



Here are the original pictures posted on diychatroom site


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## barlav

I am in the process of framing my basement. I have 2X4 walls that connect to a soffit. Here is the beginning of my fire blocking. Does this look correct? And, do I need to do anything with the soffits themselves where they meet the floor joists? I used 2X4 blocks between the studs to prevent flow up into the soffit and then tightly packed in insulation between those blocks and the foam insulation on the concrete walls to plug the gaps so there is no vertical to horizontal flow. I have also added a vertical board (along the third stud from the right) to prevent spread behind the wall. I will fill any remaining gaps there with fireblock foam. I appreciate this thread and the education it has provided! I want to get this right and feel comfortable with this before I cover it up with drywall. Thanks!!

Here is what I have so far. The soffit surrounds the entire room for a tray ceiling. The partition wall on the right side of the room (with respect to this picture) will only be drywalled on one side and unfinished on the other. The soffits will contain can lights and I plan on putting non faced fiberglass insulation in both the floor joist cavities above, the soffits and between the wall studs on the outside walls along the concrete. I wish I had put drywall up against the bottom of the floor joists before doing the soffits but I didn't. What else should I do, if anything, to make the fire blocking correct?


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## Termite

Barlav it looks like a pretty good job. Two things I'd address:

1) The foam board will burn fast and hot, so I'd treat it like it isn't even there. Instead of fireblocking TO it, I'd fireblock PAST it. Packing fiberglass to the foam is good for preventing air movement to feed a fire, but in an involved fire it will not perform as intended because that foam board will dissapear in a heartbeat. 

2) With #1 in mind, don't forget to address horizontal movement of air and fire between the foundation wall and the studs. The fire cannot have more than 10' of horizontal movement potention before hitting a fireblock.

I'm just not a fan of foam board being an integral part of a fireblock. I firmly believe that the foam needs to stop at the fireblocks so they are continuous to the foundation in this case.


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## barlav

Thanks so much for the feedback and additional ideas! 

So, there is nothing that should be done with the soffits? I was wondering with them being open up to the joists above if it needed any blocking there or anyplace along the run of the soffits that surround the room? Or will the insulation that I put in them accomplish enough fire block for me?

I think I see what you mean about going past the foam. I imagine I could cut "slots" into the foam board and extend blocks right to the foundation and fill in the gaps with fire block foam or insulation?

I have addressed the horizontal movement with that additional vertical stud (shown 3 studs in from the right) and will fill in the gaps with packed insulation or fire block foam. But first I will make that vertical stud and replace it with one that will get all the way to the concrete. 

Thanks again! This is an amazing resource!


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## Termite

No problem Barlav, glad its helping. 

You do not have to isolate horizontal soffits/furdowns from the horizontal floor joist spaces. Fireblocking is intended to isolate vertical spaces from horizontal spaces, so as long as your vertical wall spaces are not open to the horizontal soffit or floor joists, you're good.

What you propose with removal of the foam at the fireblocks is a good idea from a fireblocking standpoint. That would be what I'd do, sealed up nice and tight with fireblocking foam from an insulating standpoint. I'd suggest contacting your inspector to make sure what you do will satisfy local requirements.


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## barlav

thekctermite said:


> No problem Barlav, glad its helping.
> 
> You do not have to isolate horizontal soffits/furdowns from the horizontal floor joist spaces. Fireblocking is intended to isolate vertical spaces from horizontal spaces, so as long as your vertical wall spaces are not open to the horizontal soffit or floor joists, you're good.
> 
> What you propose with removal of the foam at the fireblocks is a good idea from a fireblocking standpoint. That would be what I'd do, sealed up nice and tight with fireblocking foam from an insulating standpoint. I'd suggest contacting your inspector to make sure what you do will satisfy local requirements.


Great thanks! That's good to hear because I wasn't sure how I would even go about the soffits. Thanks again for this help and for the time you put in on this! It is much appreciated!


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## InmatesRunWild

Thanks for the pictures. barlav, don't you have to do anything to block off the soffits at 10ft horizontal intervals?


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## legende

has anyone taken a look at my pictures above ? wow, this was posted back in apr of last year and i've actually suspended work until i got permits; if it doesn't look secure, please let me know before i continue on and get this inspected. thanks in advance -legende


----------



## Termite

legende said:


> has anyone taken a look at my pictures above ? wow, this was posted back in apr of last year and i've actually suspended work until i got permits; if it doesn't look secure, please let me know before i continue on and get this inspected. thanks in advance -legende


Legende I'm still having a very difficult time telling what I'm looking at from your pictures. The sheetrock is an acceptable fireblock but it must be done in a workmanlike manner. The cutout around the pipe would be a problem unless there is blocking at the seams. Plus everything must be fireblocked tight with fireblocking foam or other listed fireblocking sealant.


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## Santa

Absolutely GREAT. Thank you !!!!


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## barlav

InmatesRunWild said:


> Thanks for the pictures. barlav, don't you have to do anything to block off the soffits at 10ft horizontal intervals?


I could do this easy enough but I'm not sure if it's required? I can see where it would benefit if the soffits ran perpendicular to the floor joists above. If the soffit runs parallel to the joists then I'm not sure what benefit it would serve if they aren't blocked off to the joists above?


----------



## legende

thekctermite said:


> Legende I'm still having a very difficult time telling what I'm looking at from your pictures. The sheetrock is an acceptable fireblock but it must be done in a workmanlike manner. The cutout around the pipe would be a problem unless there is blocking at the seams. Plus everything must be fireblocked tight with fireblocking foam or other listed fireblocking sealant.


thekctermite, Sorry if pictures are consuing. Had pictures in previous postings of more a panoramic view of the close-up pictures above. I was thinking of just wedging some unfaced fiberglass insulation at seams between sheetrock and top plate , and around the pvc pipe, if I left it as is right now. But, anyway, I think I'm going to redo the sheetrock fireblock against the foundation, make it wider and nail the top plate against it - I think that should be fine right? Do I then need to get some 3M firecaulk and seal sheetrock against the foundation wall(sheetrock's opposite end from top plate). This is going to be difficult as is barely visible and there's no space to maneuver the caulk gun probably.


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## nateshirk

Awesome Thread.

I'm almost done framing my basement. And now I see I have more work to do. I'll try to get some before and after pics to make a small contribution to Termite's huge one. 

And it's so releaving that ONE other person on this site doesn't use the foam board insulation method. I didn't choose not to. It was just too late before I found out about it, and I wasn't starting over. Now I have a really good reason. And it makes plenty of sense. Sorry. No disrespect to GBR and Homesealed. You guys both provide tons to the site. I'll be the first to commend you and post "the wrong way" if I run into a dissaster with my fiberglass batts. 

So once I completely fireblock the entire top plate. Then seal the bottom plate with any other foam (even though I SHOULDN'T have to). Won't that prevent the convective(SP) loop?


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## nateshirk

OK, so I need to fireblock this gap between the wall and top plate. But not where it goes into the room at the end. 

And then above the elecrtical panel.


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## nateshirk

Then I have this big ole' mess. I need to fireblock anything that opens up into the soffit, correct? That's going to be tricky.


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## nateshirk

Fireblock from wall to top plate here? It's built out for the pipe to be behind the wall.
*oh, and since it's longer than 10' long, I need to fireblock somewhere in the middle. So 3/4" plywood cut to length, notched for the pipe, and sealed is what I need to do?


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## nateshirk

This other wall is pretty open behind it, and will have access panels. So I need to fireblock the whole top, and in the middle vertically since it's a 13' wall? It's framed for built in shelves, not access panel's THAT big.

Speaking of acces panels. Those need to be sealed up too, right? So no air can get in?

And in the bottom pic, that soffit opening, into the same room as mentioned above, doesn't need fireblocked. Correct?


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## PatrickG

I have a similar set up where I need to build a wall out from the plumbing and also in front of my electrical panel. I would be interest to know if you can treat it like a partition wall and just dry wall on both sides.


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## DIYHomeTheater

Termite said:


> When you have a wall adjacent to a set of stairs, you must prevent the wall studs from opening up into the concealed space under the stair.
> 
> Sometimes stairs are framed unconventionally. That is the case with winder stairs or circular (not spiral) stairs. A conventional stringer usually isn't used. Instead, each wedge-shaped tread is supported by horizontal framing that is supported by studs in an adjacent wall. A block is needed in this circumstance. I find it easiest to locate the block in the wall instead of under the stair. A 2x4 block between the studs just under the concealed space under the tread (and often just above the tread, depending on the wall) does the trick.
> 
> I'll work on getting a picture of this as soon as I can find one!


The inspector told me that I need to fireblock the enclosed area under stairs. The IRC states, '*Enclosed accessible space under stairs shall have walls and ceilings protected with 1/2-inch drywall on the enclosed side.*' I am trying to demystify this seemingly simple statement.

Attached are pictures of the under stairs area that I have walled off. Inspector was vague in telling me _exactly _where to fireblock. What I gleaned was that I need to


put drywall under the stringers of the curved staircase
along the inside radius wall that extends part way on the left from floor to stringer
I am not sure if he wants me to put drywall on the right wall where the curved stair case touches the studs tangentially (like an arc touching a straight line in a tangent). Any help will be greatly appreciated. 

Thank you!


----------



## toobhed

Thanks for all of the great info.

If I understand the horizontal soffit requirements correctly, I believe I only need to block the section that is adjacent to the wall. Here is a picture of a soffit that will end at a window opening. The placement of the hvac trunk is inconveniently right in front of the window. Hopefully these pictures will explain.


























The window openning will hopefully look like this (from first and third pics):

















The soffit butts up against the wall next to the window but opens up to let the light in, then it connects to the wall on the right and will be concealed. Does it look like I only need to fireblock here where I indicated?


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## Big-Bro

AND!!! Don't breath the stuff, (fumes), either!


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## Big-Bro

Throughly have enjoyed reading your info on the fireblocking subject! Thanks for sharing your knowledge with all of us. I just wanted to share some info I heard from several Fire Chiefs/Fire Inspecters, I have spoke/delt with on some commercial jobs I have run. Many of them have told me that one of the biggest problems, when called out on a fire, they have is actually finding the actual fire. The problem happens, especially on older buildings, is the structure when built or remodled, was not properly, fire-blocked/fire-stopped/or draft-blocked. This is allowing the smoke to travel freely throughout the structure, costing firefighters more time to locate the actual fire, and allowing the fire to grow larger each second it is not found.


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## hellonoko

First off thanks for this great thread on fireblocking.

Second. I am insulating my daylight basement and am not exactly sure of how to do the fireblocking.

On the left I have interrupted the vertical span of the Foamular insulation with a 2x4 behind my furred out wall and then put in a block in the rim joist area.

On the right the Foamular goes all the way up into the upper level floor through the rim joist area and the furred out wall ends at the joists.

Which method is correct?


----------



## ACR_SCOUT

Termite said:


> I definately encourage those of you working on framing basements, etc to post fireblocking-related pictures or questions on this thread. The more pictures there are, the more people will learn about how to do it right. :thumbup:


Here are two questions about basement fire blocking.

My plan (not formalized) is to glue 2" foam board to the foundation blocks and then build the 2x4 walls against that. At the top where the insulation and the wall top plate meet the floor joist I was going to use 1/2 drywall across the floor joist before installing the foam board and wall studs.

According to what I read here, every 10 leaner feet of wall I have to have fire block. Does that mean I need to cut a channel through my insulation to install this fire block?

What about the bulkheads built around the heating ducts and the engineer lumber span support? How do I fire block that?

Thank you,
Fred


----------



## itsnotrequired

ACR_SCOUT said:


> Here are two questions about basement fire blocking.
> 
> My plan (not formalized) is to glue 2" foam board to the foundation blocks and then build the 2x4 walls against that. At the top where the insulation and the wall top plate meet the floor joist I was going to use 1/2 drywall across the floor joist before installing the foam board and wall studs.
> 
> According to what I read here, every 10 leaner feet of wall I have to have fire block. Does that mean I need to cut a channel through my insulation to install this fire block?
> 
> Thank you,
> Fred


i am finishing my basement with a similar insulation method you are describing. well, i am technically still in the planning stages but did stop by the inspector's office to get their input on a few items, one being fireblocking. they said if i take the xps all the way up to the ceiling joists, i wouldn't need any additional vertical fireblocking (wall less than 10' high). i'm not totally comfortable with that so i am going to use 1/2" rock on the bottom of the joists to cover the top of the xps and extend it across the wall top plate, like you describe.

as for horizontal blocking, they said i didn't need any of that either. good deal for me since channeling the foam board to insert horizontal blocking compromises the thermal and vapor retardation properties of the insulation system. this can be somewhat overcome with additional caulking but it is not ideal, from an insulation standpoint. i don't plan on doing this for my finish. i figure fire moves easier in the vertical than horizontal direction.

still sort of surprised that i don't really need ANY fireblocking per the inspector...


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## hellonoko

@itsnotrequired and @ACR_SCOUT

I am doing my basement right now as per my diagram right above ACR_SCOUT's post 'continuous Foamular'

My inspector also did not care about fireblocking, especially horizontal. (every 10 feet). I even took in that picture I made of how I was going to do it and they said it's fine.

But they did want me to glue all studs (cedar or pressure treated, i went with cedar) to the XPS.

Depending on if you are going to also put foam board in the spaces between studs? That gives a fire very little or no area to grow in and the glued studs seal off each 16" on center section to limit the oxygen supply I suppose.


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## Maintenance 6

hellonoko said:


> First off thanks for this great thread on fireblocking.
> 
> Second. I am insulating my daylight basement and am not exactly sure of how to do the fireblocking.
> 
> On the left I have interrupted the vertical span of the Foamular insulation with a 2x4 behind my furred out wall and then put in a block in the rim joist area.
> 
> On the right the Foamular goes all the way up into the upper level floor through the rim joist area and the furred out wall ends at the joists.
> 
> Which method is correct?


 The system on the left is correct. In the right hand plan, fire would melt and burn the the formula R away and enter the cavity between the joists. On the left a fire in the stud cavity would need to burn away the 2x4 fire block before entering the joist cavity. The block would buy significant time by slowing the fire spread.


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## hellonoko

@Maintenance 6

That is what I thought as well along with double studs ever 10' but my inspectors didn't seem to care.

They also said they don't care about what I cover the walls with. I asked if paper mache was acceptable and they said yes.

So I guess its important to ask the inspectors eh.


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## Maintenance 6

Sounds like the inspector either doesn't know his job (imagine that?!?!?), or doesn't care. I would still do it right. It is your home, property and family you are protecting by doing the right thing. If somebody opens the walls on one of my jobs years down the road at least they won't say that I was a hack. More likely they will curse me for overbuilding. I like it that way. There is even a good chance they won't need to open things up and rebuild, because it will still all be good. You have to ask yourself which way would you like to be perceived?


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## rightit

DIY_JC said:


> I've thought of putting 3" pvc through the firestop... but honestly, I wouldn't want to cap it. If I cap'd it, then I would have to tear the walls apart again next time I added/changed cables. Obviously, that would defeat the firestop. Slightly better I suppose would be to stuff fiberglass into the pvc, perhaps in addition to fire-caulk around the outside of the pipe.
> 
> If you did cap it, do people drill a hole through the cap to allow the wires through?


Interesting thread.

Since I didn't see resolution for this issue, thought I'd respond. I ran 
1 1/4" PVC conduit in my walls for future network, video and audio wiring. Given that I've soundproofed the space and have plenty of fire rated putty pads, my plan is to stuff putty pad the conduit at both ends (where the wire exits the conduit into the 4x4 box and in the attic, where the conduit ends and is open). Ensuring a complete seal, of course.

The putty pad is advantageous in that:

1. It's fire rated
2. It's an essential part of air-sealing the space
3. It allows easy access for future wire runs. Just remove putty pad stuffing, run wire and replace putty pad stuffing (same putty pad if useable, new if not).

Putty pads aren't exactly cheap ($5 per 7x7 pad, give or take), I think fire caulking could also work well. Although a bit 'messier' to remove and non-reuseable, it is cheaper and easily obtained and used. All that and air sealing and firestopping.


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## prican_2000

*Wow!!!*

Thank you all!!!!:thumbsup:

I am a Newbie and in the process of having my house built but I opted on not having my basement built and using those credits for other items in the house so I will be building my basement myself. I have read thru all 14 pages and at first I was a lil foggy about the whole Fireblocking concept (actually I didnt even know anything about it until I found this website) but it was not until I saw the pics posted by Barlav and hellonoko that it cleared it up for me. THANK YOU!!!!

I will ensure that I adhere to the Fireblocking regs posted here when I begin my Basement framing. :thumbup:


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## buildit45

*DIYer just trying to finish a basement*

So I came across this thread a little to late I think. My framing is up and now I need some help on how to fire block it. 

1. Dow Thermax Sheathing was already on the walls so I left it there and framed next to it. What do I do for horizontal fire-block?









2. Had to frame around waste pipe not sure hot to fire block.









3. Left space for HVAC return air in framing, I cut the thermOpan and found that the return air for the existing connection goes through the floor. 









4. Lowered bathroom ceiling do I have to add blocking inbetween each stud right below where the ceiling drywall will be?









Thanks for any help


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## ccleme11

Im going to be finishing my basement soon and not sure if i missed it in the previous threads but my question is;

With the insulation in between the floor joists, do i still need to fire block at the top of the exterior walls or is this sufficient?


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## jonhayden

This is a great thread and I appreciate all the info. I'm adding a bedroom to my basement and fireblocking the soffit is still confusing me. From what I've read in this thread, it sounds like I only need to fireblock the soffit where it connects to a vertical wall, right? So I just want to confirm I DON'T need to put fireblocking where the joist canals meet the soffit like in the picture I posted. I don't need to put fireblock in the red area below, right? It just seems that if a fire started between the joists, I'd want to stop it from entering the soffit area.

Thanks,
Jon


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## spaceman spif

Yet another thread that makes me think "This is great info! I'm glad I found this before I continued my project any further!" and at the same time makes me think "Well...looks like I'm not as close to being done as I thought."


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## Clutchcargo

I notice big orange box sells 3 types of 3M fireblock/stop. Red, yellow, and gray.
My applications are sealing off the steel fireblock that I added around the chimney and also sealing some blocking between the floor joist and stud walls. Which product do I use?
Thanks,
Cliff


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## ccleme11

DIYHomeTheater said:


> I am going to frame my own interior basement walls. I have R-13 foil backed insulation ('pink stuff' fiberglass) attached to basement walls. My jurisdiction recommends the attached method for fireblocking.
> 
> My question is:
> 
> Is inserting 1/2" drywall between top plate of stud wall and ceiling (blocking or joists) strong enough? I am not sure if the stud wall may cause the drywall to crack. Also, the diagram shows that the continuous fireblocking drywall terminates roughly half-way through the width of the top plate. To me it sounds easier to simply extend it all the way to the inside edge of the top plate and then let it butt up against drywall that will be attached to the ceiling. Any thoughts? Thanks


I have the same type of construction in my basement... is this how it should be done? Or does the OSB/Drywall need to be touching the Concrete Wall?


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## ccleme11

would this work for fire blocking?


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## ccleme11

Can anyone help me out with the previous post about the fire-blocking for my basement? I'm located in Parker Colorado.

thanks,


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## jonhayden

ccleme11 said:


> I have the same type of construction in my basement... is this how it should be done? Or does the OSB/Drywall need to be touching the Concrete Wall?


Insulation between the framing and concrete wall is all you need. That is your fireblocking. No need to add pieces of drywall.


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## ccleme11

Im pretty sure fire-blocking needs to be continuous around the perimeter of the Basement where the Basement walls meet the upper floor joist, so to keep the fire from spreading to quickly... right?


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## jonhayden

ccleme11 said:


> Im pretty sure fire-blocking needs to be continuous around the perimeter of the Basement where the Basement walls meet the upper floor joist, so to keep the fire from spreading to quickly... right?


I'm guessing you have the blanket insulation on all the perimeter walls. And that your walls are pushed up against the insulation so if a fire started in the wall, it won't go anywhere because of the insulation. Or it would burn slowly. My town inspector said that was all I needed along the concrete walls. So ask your inspector to make sure. You also need to make sure you use fireblocking foam in all the wire holes in the joists and wall framing to keep fire from spreading from joist channels. I think that's about all I did. Oh, I also had to put up blocking in the soffet every 4 feet so if it entered the soffet, it wouldn't go far. But your inspector is who you really want to check with to make sure what they're looking for specifically.


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## Fordstanger

Echo the great thread comments. Really helps in my current remodel.


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## Theodore2

*fireblocking at main electric panel*

Hi,
I'm finishing my basement and coming 'round to the main electric panel. Many of the photos and examples of fireblocking that I see online are of a few discreet pipes or NM/romex cables penetrating a top plate. But in my case, I have a whole spaghetti-bowl of wires coming through the "plane" of the top plate. I know that fireblocking needs to extend to touch the sill plate, but in my case it's almost impossible to do so without encountering 2dozen armored cables. What does one do in such a messy situation per the attached photo? Mine is even more complicated by fact that my panel is paralell to the flood joists, so there is no simple top plate to install and I have to make frames to hold one in place.

All advice and observations greatly appreciated.
Thanks
Theodore


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## Anti-wingnut

In a case like yours, annular spaces can be fireblocked with a combination of rock wool insulation and a recognized fire caulkin such as this.
http://multimedia.3m.com/mws/media/592250O/09-fireprotection-emd-2009-catalog.pdf


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## MrElectricianTV

Theodore2 said:


> Hi,
> I'm finishing my basement and coming 'round to the main electric panel. Many of the photos and examples of fireblocking that I see online are of a few discreet pipes or NM/romex cables penetrating a top plate. But in my case, I have a whole spaghetti-bowl of wires coming through the "plane" of the top plate. I know that fireblocking needs to extend to touch the sill plate, but in my case it's almost impossible to do so without encountering 2dozen armored cables. What does one do in such a messy situation per the attached photo? Mine is even more complicated by fact that my panel is paralell to the flood joists, so there is no simple top plate to install and I have to make frames to hold one in place.
> 
> All advice and observations greatly appreciated.
> Thanks
> Theodore


How do you plan to finish that space where the electrical panel is located? If you are just going to make it a utility closet, I don't think that you need to do anything. Did you get permits for this work? If not I strongly recommend that you do.

Consider future accessibility for the electrical panel. If you frame around it and enclose it in the wall it will be difficult to install another circuit. Many times I have received calls to do work in homes with completely finished basements. To add a circuit sometimes entails cutting holes in ceilings and walls.


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## JamesCE

Anti-wingnut said:


> In a case like yours, annular spaces can be fireblocked with a combination of rock wool insulation and a recognized fire caulkin such as this.
> http://multimedia.3m.com/mws/media/592250O/09-fireprotection-emd-2009-catalog.pdf


Great thread and from my understanding through reading it... no blocking is necessary in unframed areas.


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## JamesCE

Does fire blocking have to be air tight? I ask specifically in regards to cutting a 3/4" OSB board and putting it on top of the top plate. As tight or close I could have it to the concrete and 2x4 there maybe tiny gaps... should i seal them up?


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## JamesCE

One more thing for those listening out there lol

When you fire block every ten feet vertically, do we need to remove the wrapped insulation from the wall in that section?


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## dgeist

JamesCE said:


> Does fire blocking have to be air tight? I ask specifically in regards to cutting a 3/4" OSB board and putting it on top of the top plate. As tight or close I could have it to the concrete and 2x4 there maybe tiny gaps... should i seal them up?


JamesCE, the purpose of the blocking is to reduce the spread of heat, flame, and fuel. Oxygen is fuel for flames, so anyplace it can reach a potential flame reduces the effectiveness. If you have blocking in place that just isn't tight against the adjacent surface, a bead of urethane caulking or fire foam will seal it right up. Will it make a huge difference? Perhaps not, but it might give someone the crucial seconds to get themselves or loved ones to safety in a blaze. If it's a couple bucks and a couple minutes, why NOT do it? 

On the insulation question, are you using FG batts that are paper faced and are they between the joists or behind them (in a narrow cavity)?


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## dgeist

*Framing / blocking behind duct chase*

I'm doing a new finished basement built-out and am having new HVAC supply trunks run around the perimeter ceiling of the space. I have 2x10 floor framing on a block foundation and XPS+polyiso+foam blocking in the rim joist cavities now. The cavities with duct boots will be a special problem and likely just get a lot of foam, but for the rest of the wall, I'd like to keep the trunks as high and tight as possible.

I'll be putting a solid wall of XPS up from floor to a 3/4" horizontal ply blocking screwed under the joists (so, full floor to ceiling). Does it make more sense to bring the framed wall all the way up to the plywood/joists then put intermediate 2x blocks at the lower-edge where the chases will intersect to prevent spread from wall to chase or just build the top plate to the lower edge of the chase and cover the remainder of the XPS in the back of the chase(probably 10-12") with something like wallboard? I'm leaning towards the former, but hate to give up those precious 3.5" of usable space next to the wall where the ducts could be tucked :wink2:


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## rmnhsd

nice thread!


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## vegas777

Please help! I'm having trouble trying to figure out how to fire block this basement with goofy framing. To make matters worse, like a dummy, I already put in rigid foam and framed in front before falling upon this useful thread and learning about fire blocking. Please reference photos, see the gaps above and below the beam and the major void where the wall runs parallel to the joists. Just blocking top conventionally like previous post suggest is not functional. Could I get away with just cutting foam along where the concrete block stops and inserting pt lumber blocking to foundation wall and seal with fire stop foam? This means it would not go to top of wall though. Any ideas? It is not getting inspected but I am ocd about doing things right. Thanks in advance to those more enlightened than I.


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## Keptphree

I wanted to get a little clarifying on my fire blocking before I venture onto electrical. For the vertical that is 10ft min, if it required where the wall starts? One wall starts midway in a storage area and then 10ft from that I have vertical blocking. Do I need to seal that starting void so essentially making a 10 ft wide sealed section of the wall? All my top plate and 10 ft is done but needed to know about that initial opening of the wall where it will be unfinished i.e. storage areas.


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## mvcardillo

Termite,

Instead of using plywood or 2x4s, can I put Roxul rockwool insulation inside of the floor joist area on top of the stud cap? I have cut 11" pieces and pushed them into the cavities between the joists. The rockwool is now even with the edge of the stud cap. I also used fire great stuff and filled the 1/2" gap between the foundation and the stud cap. Is this ok. 

I have also filled all holes made by wires and pipes. After reading your post, I will now fireblock every 10 ft., the vertical stud and cap to make it completely sealed.

I am worried that the rockwool is not enough. Please let me know.

Thank you.


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