# Thin insulation material needed



## Rav (Dec 7, 2011)

Our house was built in 1931, plaster walls with no insulation. In one bedroom the walls were covered (before we bought the house) with very thin plywood, we suppose to hide cracks or perhaps old water damage. About 10 years ago we had the plywood painted. Besides being ugly, the plywood is splitting, and the (exterior) walls are cold. We want to have the plywood removed and drywall put up (the ceiling is already drywall). But as long as we're doing that we figure we should try to insulate the walls. We know about drilling holes in the plaster and trying to fill the walls with foam or whatever, but we would like to avoid that if at all possible (and we've been told there's virtually no space between the exterior stone and the plaster). We're thinking we'd prefer some sort of thin insulating material put on between the plaster and the drywall. Thin, because we don't want the walls "pushed" into the room too far (window frames would then have an odd "recessed" look). I know that thicker would provide a better R value but we'd like to know how well we could do with something thin, i.e. better than no insulation at all. Just for the sake of discussion, I recently installed Reflectix radiant reflector (BP24025) behind our radiators; that's what I call thin (5/16") insulation. I'm not saying that specific material would be what we should use behind the drywall, just trying to indicate what I mean by thin. Is there anything specific anyone would recommend, and what sort of R value we might expect to achieve with it? Thanks.


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## Windows on Wash (Aug 30, 2011)

Reflectix will not work in this application nor does it work in any capacity as and insulator. Radiant barriers need and airspace to work.

I know you know that, I was just pointing that out for other readers.

In terms of insulation, there is nothing out there that will supply any real R-value at the 1/2" thickness range. Closed cell foams and Polyiso foams generally have the highest R-values per inch and they are about 6-7 per inch.

Putting a 1" thermal break between the existing walls and new wall would help thermally uncouple the house from the outside wall pretty well.

There are some much higher R-value substances out there but they are more exotic and much, much more expensive.


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## Rav (Dec 7, 2011)

Thanks for your reply, W on W. I would consider "more exotic and much more expensive," if they'd work for what we need, since you say they're much higher R-value. I'd appreciate it if you could provide some product names for those higher-end products, and where we could find them. Thanks.


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## joecaption (Nov 30, 2011)

Good luck with that idea. Build the walls out, add extention jambs, insulate
And save at lest 25% on you heating and cooling cost from then on.


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## Windows on Wash (Aug 30, 2011)

Rav said:


> Thanks for your reply, W on W. I would consider "more exotic and much more expensive," if they'd work for what we need, since you say they're much higher R-value. I'd appreciate it if you could provide some product names for those higher-end products, and where we could find them. Thanks.


Nothing that is suitable for residential construction.

If you want, look up Aerogel.

+1 to Joe's suggestion. Just furr the walls out and use a proper insulation layer. You won't loose that much square footage.

Even if you furred out the wall by 6", you are only loosing 15 sq/ft in a 15' by 15' room.


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## joecaption (Nov 30, 2011)

Dispite the fact "you do not want to" if you really want these walls insulated removing wants on the walls now building a 2 X 4 wall and add R-13 and have a warm wall. 
This would also allow you access to run new wiring, more outlets, seal up any holes you find, form a thermal break, insulate around the window frames.
I did this and added replacement windows in my own cement block house and my heating bill went down 50%.
You only need to do the outside walls.
Since I did all the labor myself it only cost about $200.00 in materials. (small house)
When I removed the old tile board from my walls I found holes where air had been getting in everywhere, bare wires, burned wires, temites that I never knew where there ect.


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## AGWhitehouse (Jul 1, 2011)

I'd recommend (at minimum) furring the wall out 2" with 2x4 studs turned sideways and held off the stone face by 1/2" Then use 2.0lb closed-cell foam to achieve an R-13.4 within the wall space. Adding an extra inch or two to that will drastically improve the feel of your room...


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