# second floor overhang issue



## TazinCR (Jun 23, 2008)

Some pictures would help a lot.


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## jammer7 (Jan 2, 2009)

Sure you bet!


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## Winchester (Aug 27, 2008)

I have a similar issue that was addressed to me by my Energy Auditor last spring. The Cantilevers need to be sealed. You can see what I'm talking about from the link provided. You'll have to block this off from the main part of the house.

IMO, I think you might want to seal this board from your images with some caulk before you secure it in place. Then I'd fill in any cracks with caulk and/or foam. Caulk up to 1/4" and foam in the larger cracks.

Best of luck.


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## Aggie67 (Dec 20, 2008)

Not for nothing, but that insulation's pretty thick. If anything check for fit up. I was expecting to see worse. My house is very similar (1975 bi-level). I have cold weather issues, but it's my windows that suck. I've inspected my attic and each of the overhang areas, and the soffit insulation is in decent shape. But I can walk by the windows and feel the draft. Plus my furnace is original equipment, even though there are 2 significant additions on the home. 

Check the obvious: drafts, insulation, caulking. Some of those pieces of siding in your pics have pretty decent gaps. Now that the soffit is half out, check for a vapor barrier, and caulk all the gaps. One issue I have in the addition above my garage is the guy who ran the duct through the overhang into into the wall space did a lousy job insulating. I can feel the hot air coming in through the duct during the summer, and the cold air coming in during the winter. But I've been busy, so I haven't had time to rip out the garage ceiling to redo it. So check that, also.

Also, my eldest daughter's bedroom is in the room that corresponds to windows below your overhang in your pic. You can store meat in that room during the winter. I'm going to check this summer, but if the rear wall of the house is any measure, I've got crappy foundation wall insulation.


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## Winchester (Aug 27, 2008)

Also, from what appears to be dirt on your pink fiberglass is where the air was coming in and the fiberglass is acting like a filter. Something also pointed out to me for my rim joists in the basement.

Best of luck!:thumbsup:


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## jammer7 (Jan 2, 2009)

awesome, thanks for the replies guys! 

ya looking at the catilever diagarm, i see a few problems, there is no blocking in place, and there is no vapour barrier, I dont know how addressible these will be, i might be able to set something up with some rigid insulation as blocking, as i dont know how effective trying to get blocks of 2x12 in there will be. 

hmm this one will be interesting! 

thanks again guys! 

Brett


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## Wildie (Jul 23, 2008)

Two feet of insulation would not make this situation any better! Insulation can only slow the flow of heat! Insulation cannot generate heat! For instance, a box can be made with R30 insulation all around, but eventually, the inside temperature will become equal to the outside temperature! Now, if a incandescent lamp is placed inside, the inside temperature will stay warm, as heat that is lost will be replaced by heat from the lamp! The problem in this instance is that heat that is lost through the insulation, is not being replaced! Heated air must be allowed to circulate between the insulation and the sub-floor above! My son had a similar problem, where the ceiling in the basement was drywalled, and there was no airflow in the joist cavity! Installing vent louver's in the ceiling resolved this problem!


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## jammer7 (Jan 2, 2009)

hey Wildie, im not sure I completely understand what your saying, in this case the living room directly above the area shown in the pictures attached is a regularly heated room, its just that exessive cold air is penatrating through to floor below through the joist cavity that hangs over the basement celing on the outside of the house.

I wasnt planning on adding another foot of insulation, i was simply pondering adding some cut pieces of rigid insulation within the joist cavities to serve as blocking down the joist cavity

in the basement below i have a standard drywalled celeing, and im not sure what your suggesting, installing vent louvers in the finished celeing of my basement? i dont know if ive seen that on the interior of a basement celeing before, are you saying i need to heat the joist cavities? can you provide some more info or show me an image of that? 

thanks for your input i appreciate it


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## jerryh3 (Dec 10, 2007)

You could give a call to a local insulation company that does spray foam and see what they would charge. Spray foam should cut down on the air infiltration and give a better thermal barrier than the fiberglass insulation.


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## Wildie (Jul 23, 2008)

jammer7 said:


> hey Wildie, im not sure I completely understand what your saying, in this case the living room directly above the area shown in the pictures attached is a regularly heated room, its just that exessive cold air is penatrating through to floor below through the joist cavity that hangs over the basement celing on the outside of the house.
> 
> I wasnt planning on adding another foot of insulation, i was simply pondering adding some cut pieces of rigid insulation within the joist cavities to serve as blocking down the joist cavity
> 
> ...


 What most people fail to understand is that insulation merely slows the flow of heat! Its akin to water flowing through a screen. The finer the mesh, the slower the flow. Never the less, flow it will do! A house may be insulated, but if the furnace is out it will eventually cool to the outside temperature! In your case a heat source is needed to replace the heat lost through the insulation. At the moment, the only heat source is from above, and through the floor and this flow is not enough to make up the heat loss through the insulation. Somehow, you will have to find a way for warm air to circulate between the insulation and the floor above. Many times I've seen pipes frozen under a sink! The solution was to leave the cupboard door open and then there's no more freezing! Same idea!


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## jammer7 (Jan 2, 2009)

One last question as i think i have plan of action to deal with this in the way that is the most feasable at this time, 

if you look at the pictures i posted, is there any value in me removing the insulation so the floor joists and subfloor above is exposed and put a continuous piece of vapour barrier, that is wrapped along the bottom of the joists as well? and them put the insulation back in the joist cavities, that would be now wrapped in poly? 

what do you guys think, its kinda hokey but i cant really get a vapour barrier in anyother way.


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## rustyjames (Jul 20, 2008)

I would investigate the spray foam idea mentioned above; shooting the joist bays, which would serve as a better air barrier than that fiberglass.


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## Wildie (Jul 23, 2008)

jammer7 said:


> One last question as i think i have plan of action to deal with this in the way that is the most feasable at this time,
> 
> if you look at the pictures i posted, is there any value in me removing the insulation so the floor joists and subfloor above is exposed and put a continuous piece of vapour barrier, that is wrapped along the bottom of the joists as well? and them put the insulation back in the joist cavities, that would be now wrapped in poly?
> 
> what do you guys think, its kinda hokey but i cant really get a vapour barrier in anyother way.


 If the insulation was installed correctly, there should be a vapor barrier in place, under the sub-floor! If not, what you suggest is a good idea, but this will not make it any warmer! If it were mine, I would install foam ventilation channels (commonly used in attics) between the joists, closed at the ouside end with insulation, but open to ceiling space inside. Then reinstall the insulation and the lower panel! Then try to get some warm air circulating up there!


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## Winchester (Aug 27, 2008)

You don't want air circulating in this area. Thats ridiculous. Why would you want to ventilate into a basement when the process of eliminating drafts and improving efficiency is to seal and insulate??

This area of the house needs to be "sealed" and is in no way similar to an attic or roof. Block the area as shown earlier, seal the blocking as well as the horizontal area that sticks out, replace the fiberglass to fit snug, (foam would work great too) maybe replace the board that was removed while using an adhesive around the edges, seal perimeter again and be done with it.


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## Wildie (Jul 23, 2008)

Winchester said:


> You don't want air circulating in this area. Thats ridiculous. Why would you want to ventilate into a basement when the process of eliminating drafts and improving efficiency is to seal and insulate??
> 
> This area of the house needs to be "sealed" and is in no way similar to an attic or roof. Block the area as shown earlier, seal the blocking as well as the horizontal area that sticks out, replace the fiberglass to fit snug, (foam would work great too) maybe replace the board that was removed while using an adhesive around the edges, seal perimeter again and be done with it.


 I guarantee that if the OP follows your direction, he will be back next year, asking how he can resolve his problem. You should read back my posts, as you have misinterpreted what I said. Yes! The board should be sealed against infiltration, no arguement here! I would have you read what I said about frozen pipes in enclosed areas, such as under sinks. Insulation in the wall behind will do no good if the heat loss is not replaced! And this is the problem here! I referred to attics and roof's in regard to the use of foam channels only and never made any reference to allowing cold air to circulate in the area in question! The area in question needs a warm air supply, to compensate for the heat lost through the insulation!


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## Tom Struble (Dec 29, 2008)

as it was explained to me a cantilever is like a cooling fin on a engine
and as long as the heat isn't being replaced along those areas
will always be colder at those areas


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## Wildie (Jul 23, 2008)

[email protected] said:


> as it was explained to me a cantilever is like a cooling fin on a engine
> and as long as the heat isn't being replaced along those areas
> will always be colder at those areas


 That's a good anology! So true!


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## Winchester (Aug 27, 2008)

Wildie said:


> You should read back my posts, as you have misinterpreted what I said. Yes! The board should be sealed against infiltration, no arguement here! I would have you read what I said about frozen pipes in enclosed areas, such as under sinks. Insulation in the wall behind will do no good if the heat loss is not replaced! And this is the problem here! I referred to attics and roof's in regard to the use of foam channels only and never made any reference to allowing cold air to circulate in the area in question! The area in question needs a warm air supply, to compensate for the heat lost through the insulation!


I have reread your posts and I do understand your under sink reference. Though similar I don't quite think they are the same however. Let me come back to this.

So we agree that the plywood board needs to be sealed and eliminating (cold) air infiltration. I think this is a *very big source* of the problem of the heat loss issue. I think you'd have to admit that the heat source in the house, as is, will have a much better chance to balance that heat loss difference? This is the lamp inside the box you reference to in another post. We also have to understand that that board itself is a poor insulator.

Now back to the other issue. I don't see how installing vent louvers to circulate air solves the problems? I think it just defers it to the basement area? After all, if warm air is allowed to the underside of the cantilevers, what's not to allow the cold air into the basement? If it's going to circulate, it has to go both ways.

Would you suggest doing the same thing to a wall and heat the back side of the drywall?

Let me say, I'm not a professional in this area but I have certainly spent a lot of time researching, asking questions, and have had an energy audit done on our home with a certified energy rater.

I too have the cantilevers issues between my first and second floor (a true 2 story house and not a split level. I have never seen or heard of anyone heating this area between floors. Nor do I plan on heating this area. Though I will look into isolating this area by first sealing and then insulating.

I'm simply only trying to help out and certainly is only an opinion but this will be all I have to say about it.

Best of luck.:thumbsup:


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## Winchester (Aug 27, 2008)

Wildie said:


> That's a good anology! So true!


And if you fill in the gaps of the fins it will not cool as efficiently??


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## AllanJ (Nov 24, 2007)

Did the cover on the underside fit tightly originally? I would go with just putting it back the way it was and caulking the edges. (Actually before that check to see that the old insulation was properly fluffed to not leave gaps here and there against the front siding and the joists.) There is (should be) a vapor barrier on the warm side of that space namely up against the subfloor but chances are it is not hermetically sealed. Therefore some moisture will get down there and the wall and underside cover need to be porous.

I would not expect the cantilevered floor to lose any more heat than an equal area of exterior wall.


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## bsix (Jan 31, 2009)

*Insulating Overhang*

Jammer I have some experience consulting in this area. I also had to register just to comment on this misinformation that I have seen in this post.

What Wilde is saying is pure rubbish. You do not want any airflow in insulation. Also 12" of insulation is more than enough, the blackness you are seeing in the insulation is showing that there is infiltration which is bringing cold air directly into your conditioned space.

Heat is tranfered through three methods, conduction, convection and radiation. In a cold climate, one really worries about the first two. While fiberglass works well for conduction, it does not not do much for convection. Thus an airflow through fiberglass can ruin it's R value. Studies in cold climates for fiberglass attic insulation have shown that it's effective R value is reduced by 30-50% just due to convection currents.

So here's what needs to be done.

1) Seal the underside of the subfloor at all cracks, especially near the outside rim joist (area with the black insulation). Canned spray foam, backer rod and caulk can all be used to help seal this. 

2) Do the same with a airstop block (blue foamboard is ideal) from the basement side. Fiberglass insulation does not stop drafts and is not effective with an airflow through it.

3) Install insulation with kraft paper facing side up.

An alternative is as someone said, spray foam the underside. This will help seal and insulate. If you are worried about cost, you could use a hybrid method with 1-2" sprayfoam and the remainder with insulation. If you do the hybrid make sure the insulation does not have a vapor barrier.

Take care.


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## Scuba_Dave (Jan 16, 2009)

I agree with Bsix
You do NOT want air circulating
You want to isolate this area with the foam board
Then make sure it is sealed against outside COLD air

I understand what Wilde is saying, but you don't push warm air into an insulated space. Think about it, warm air, cold area, condensation

You have a floor that juts out over an open area. It will always be colder then a floor above a heated space


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## sawyerEd (Aug 9, 2008)

jammer, I agree with bsix, there has been a lot of BS in this thread. This overhang is an example of crackerbox construction. Granted overhangs can be problematic, if I owned this I would tack it back together and in good weather strip all the channel siding off, toss the moldy pink stuff and rebuild it right. This bump out should have insulating sheathing, house wrap carefully detailed and pinched under the insulating board at the basement wall then, after the insulating board is installed on the entire bumpout, bring it around the corner and all the way up to the soffit. Cut and fit the house wrap carefully around the window. Use spray foam insulation and make sure the vapor retardant layer is continous from the inside basement wall, into the joist cavity to the floor decking and out to the wall plates, all of which must be sealed so the plate and decking edge are part of the retardant layer. No warm air leaking into the joist space! Most open cell spray foams are semi-permeable to vapor so you may want to tighten up the warm side with sheet poly or latex sealer. Do not tighten up the sheathing too much, let the house wrap do what it is supposed to do, allow a slow egress of vapor while stopping the wind which pressurizes under the overhang. If you reuse the channel siding you may have to add more trim around the window. Seems like a lot of work but I think it is worth the energy you save and greater comfort level you will achieve. There are grants available for this kind of retro fit.


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## Tom Struble (Dec 29, 2008)

nobody is arguing not insulating or air sealing that area:thumbsup:


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## Tom Struble (Dec 29, 2008)

Winchester said:


> And if you fill in the gaps of the fins it will not cool as efficiently??


very true but it will still loose more heat than the basement areas its more about how the structure has more mass hanging out in mid air


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