# Fireblock and Drop Ceiling



## 325_man (Jan 20, 2011)

I have been reading about fireblocking in the basement in this forum. However, I think I am going to go with drop-ceiling for easy access and I have not seen the topic discussed before.

Is a different way of fireblocking if I want to go with drop-ceiling?

Thanks,
Nick


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## 325_man (Jan 20, 2011)

anyone?


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## TheCamper (Dec 4, 2009)

Fireblocking the top of the walls would be the same. You need to prevent the movement of a fire from vertical to horizontal. I am not sure where you are looking to fireblock in the ceiling. How large an area is the finished basement and is the use a one-family dwelling? Are you talking about a fire rated separation between floor levels as needed to separate dwelling units?


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## 325_man (Jan 20, 2011)

TheCamper said:


> How large an area is the finished basement and is the use a one-family dwelling? Are you talking about a fire rated separation between floor levels as needed to separate dwelling units?


The basement is about 1500 sq-ft. 
No, I'm considering the drop-ceiling for quick access and need to know if i have to do anything extra for fireblocking.


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## Beepster (Oct 19, 2009)

As Camper said, and as I understand fireblocking put most simply, it is to prevent fire from rising up a vertical wall and getting into a horizontal space.

Will the drop ceiling tiles be below the top plate of the walls? If so, I can not say for sure whether the walls will need to be fireblocked at or slightly below the height of the ceiling tiles. Either wait for an expert to pipe in or call your local building inspector and ask. Ultimately they are the ones that pass or fail (if under permit).

B


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## 325_man (Jan 20, 2011)

Beepster said:


> As Camper said, and as I understand fireblocking put most simply, it is to prevent fire from rising up a vertical wall and getting into a horizontal space.
> 
> Will the drop ceiling tiles be below the top plate of the walls? If so, I can not say for sure whether the walls will need to be fireblocked at or slightly below the height of the ceiling tiles. Either wait for an expert to pipe in or call your local building inspector and ask. Ultimately they are the ones that pass or fail (if under permit).
> 
> B


I have never done drop-ceiling, but in theory it should be below the top plate of the wall. And, since the wall is fireblockes, my logical mind says that there is nothing more need to be done. 

I'm hoping for an expert to pipe in.


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## leungw (Apr 20, 2009)

Hello. I think most experts would ask you to talk to your town's inspectors, since different towns would have different requirements.

I put up suspended ceiling in my basement also and there's nothing different than drywall in terms of fireblocking. Below is what my inspector wanted to see at my fire inspection regarding fireblocking:


fireblock at the top of perimeter walls, and at every 10ft horizontally.
fireblock all soffits.
fireblock spaces between joists around utility room.
bottom of stairs must be drywalled
drywall or fiberglass must be used directly on all xps insulation.


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## 325_man (Jan 20, 2011)

leungw said:


> [*]drywall or fiberglass must be used directly on all xps insulation.


Hi, can u please clarify the last bullet? If there is any picture, it would be helpful. 

Thanks!


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## leungw (Apr 20, 2009)

325_man said:


> Hi, can u please clarify the last bullet? If there is any picture, it would be helpful.


I first replaced the fiberglass in all the joist spaces with XPS. Next I cut drywalls into 10" x 48" strips and secured them on the joists around the perimeter, right against the sill above the concrete walls. I then put 2" XPS against the concrete walls and framed right in front of the XPS. I was going to leave the stud spaces empty and put drywall up. The inspector said I needed to cover the XPS with fiberglass in the joist spaces and stud spaces, to slow down the XPS from burning in case of a fire above the ceiling, or an electrical fire in the stud spaces. What he said made sense, even though no one else seemed to have to do it. In my case it was really down to getting all the XPS out, or putting fiberglass batts everywhere. I chose the fiberglass.


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## 325_man (Jan 20, 2011)

leungw said:


> I first replaced the fiberglass in all the joist spaces with XPS. Next I cut drywalls into 10" x 48" strips and secured them on the joists around the perimeter, right against the sill above the concrete walls. I then put 2" XPS against the concrete walls and framed right in front of the XPS. I was going to leave the stud spaces empty and put drywall up. The inspector said I needed to cover the XPS with fiberglass in the joist spaces and stud spaces, to slow down the XPS from burning in case of a fire above the ceiling, or an electrical fire in the stud spaces. What he said made sense, even though no one else seemed to have to do it. In my case it was really down to getting all the XPS out, or putting fiberglass batts everywhere. I chose the fiberglass.


Thanks, leungw! That is how I did mine. :thumbup:
I am pondering if it is necessary to put fiberglass batts to cover the XPS though.

This is the insulation code in my county:
* Concrete exterior walls shall be insulated with a minimum R-10 insulation
* Wood frame exterior walls shall be insulated with a minimum R-13 insulation. (do you think this is a requirement of the fiberglass batts?)


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## leungw (Apr 20, 2009)

325_man said:


> This is the insulation code in my county:
> * Concrete exterior walls shall be insulated with a minimum R-10 insulation
> * Wood frame exterior walls shall be insulated with a minimum R-13 insulation. (do you think this is a requirement of the fiberglass batts?)


2" XPS has R10. I would think a regular basement would be considered concrete exterior and XPS alone should be sufficient for the insulation requirement.

I think they are referring to first floor and above for wood frame exterior. I would check with the inspector though.


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## Gary in WA (Mar 11, 2009)

As said check locally...

#12; http://www.diychatroom.com/f98/how-fireblock-framing-37190/

Again, local codes change prescriptive codes; if a drop ceiling is lower than the top plate, add fire-blocking in the wall at that level; http://publicecodes.cyberregs.com/icod/irc/2006f2/icod_irc_2006f2_6_sec002_par017.htm

Wood is only one type of fire-blocking per code; http://publicecodes.cyberregs.com/icod/irc/2006f2/icod_irc_2006f2_6_sec002_par018.htm

The rims may/not need covering, *local *again; http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_3_sec016_par015.htm

All the basement walls connected to the drop ceiling require fire-blocking, not just the non-bearing wood wall against concrete wall;http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_6_sec002_par011.htm

Gary


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## 325_man (Jan 20, 2011)

GBR in WA said:


> As said check locally...
> 
> #12; http://www.diychatroom.com/f98/how-fireblock-framing-37190/
> 
> ...


Thanks, Gary!
Based on what I read, there is nothing more fire blocking effort that i need to do other than the normal fireblocking requirement with a regular ceiling. Let me know if you don't agree with my conclusion. 

I'm checking with local inspector for confirmation. Although, i have tried this in the past and they just don't return calls  

Nick


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## 325_man (Jan 20, 2011)

leungw said:


> I first replaced the fiberglass in all the joist spaces with XPS. Next I cut drywalls into 10" x 48" strips and secured them on the joists around the perimeter, right against the sill above the concrete walls.


I notice you say 10". Why 10"? The xps is 2" and the 2x4 is only 3.5". So the total is 5.5".


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## Gary in WA (Mar 11, 2009)

A full-height ceiling would be on top of the single/double top plate of a wall. IF the ceiling is dropped below the top plate, you need to add another row of blocking at the lower ceiling line to prevent a wall cavity fire from traveling up and past the drop ceiling, leaving the wall and entering the space above the ceiling- unless the upper (unused) ceiling plane is drywalled also. Then the fire could travel in the floor joist cavity, across the room, and go up a plumbing chase/hole you forgot to air seal. Many times the plumbing vents go to the roof, if not air-sealed between floors/ceilings, it could set the roof on fire.

Gary


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## leungw (Apr 20, 2009)

325_man said:


> I notice you say 10". Why 10"? The xps is 2" and the 2x4 is only 3.5". So the total is 5.5".


Because the fireblock at the top needs to be touching the sill plate. The sill plates in my house are not flushed with the concrete walls. They are about 4" from the interior side of the concrete wall. The drywall at the top stick out in some areas, but it doesn't matter since the suspended ceiling is about 3" down from the joists.


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## 325_man (Jan 20, 2011)

leungw said:


> Because the fireblock at the top needs to be touching the sill plate. The sill plates in my house are not flushed with the concrete walls. They are about 4" from the interior side of the concrete wall. The drywall at the top stick out in some areas, but it doesn't matter since the suspended ceiling is about 3" down from the joists.


Thanks again!
I'm doing the same as you did. I am going to seal the corner of the drywall and the sill plates with fireblock caulk and with fireblock foam for the sides where the sill plates are not flush with the concrete. 

Since the xps and frames come after covering the caulk and foam seals, do you know how picky an inspector is for wanting to see that I did the fireblocking properly? I hate to tear down frame for such situation. 

Nick


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## leungw (Apr 20, 2009)

325_man said:


> Since the xps and frames come after covering the caulk and foam seals, do you know how picky an inspector is for wanting to see that I did the fireblocking properly? I hate to tear down frame for such situation.


My inspector was not too picky. He checked a couple of areas thoroughly and once he was happy with them, the rest went pretty quickly. But this of course is different depending on the individual inspector.


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