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toddmanqa 10-06-2008 05:03 PM

Installation of Tuff-R sheet foam - in-cavity/out cavity?
am redoing the plaster walls in a room in my house in New York (I am also opening up the wall cavities to redo the electrical wiring). I don't expect to find any insulation in my 2x4 walls (house built in the 1920's). I was thinking about furring out the walls to a true 2 x 6", then cutting three layers of the 2" tuff-r to fit within the wall cavities (between the now-2x6 beams), but leaving a 1/2 gap on the edges of the sheet foam, then using spray foam to seal the gaps. Follow with 5/8 water reistant gypsum, then two layers of plaster.

The TUFF-R claims to have 12.2 R value for 2 inches. Will I get that x 3 if I put in three layers of Tuff-R? Or, since the 2x6's won't be insulated themselves, will they leak heat?

Or, does it make more sense to leave the 2x4s as is, put two layers of 2" tuff-r in the cavity, then follow with a 2" sheet on the exterior of the studs? I'm trying to avoid losing too much floor space due to bumping the walls out.

I'm pretty sure that this would be cheaper than sprayed in foam by a contractor.

Any advice would be appreciated.

Square Eye 10-06-2008 05:45 PM

The Tuff-R sheets work best as a solid, unbroken sheet. I'd suspect that the Spray you would be using would be the disappointing factor. Not even sure it will work with the Tuff-R without dissolving it on contact. Sounds like a good idea but there's a reason why it's not done by everyone. Spray foam has disappointed me more than once, I don't trust it at all but the contractor installed "whole house" Spray foam is impressive to see. InspectorD is the man here, when it comes to insulation and heating/cooling efficiency. I'm anxious to hear what his opinion is on this one too!

inspectorD 10-07-2008 05:30 AM

There I go again, talkin too much .Hehe.
I would go with a different product than the foams. They have their place but walls are not it. If you need to do the ceiling and walls a product called is a good one. I just had a long tiring discussion with one of the scientists from I learned alot more about insulations and issues with each type. For the money, this is your best bet.
I am sure there are more companies around who do the same type, check them all out and talk, talk, talk, to them about the why's.:D

Good luck.:)

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