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My basement's insides are completely unfinished. It has bare brick walls and bare concrete beams-vaults as the ceiling. I though of coating the walls and the ceiling with 2 inch thick plaster with the objective being that the house's ground floor won't be so cold in the winter. I thought of doing it myself with plaster since I do not have the budget for fibers, panels, gels, foams or any other insulation.

Can I buy a few sacks of plaster, mix it with water, apply a 2 inch coating and get a reasonable, yet inexpensive, insulation ? Would plaster make the ground floor less cold or would it be a complete waste of my time ?

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A 2" coating over an entire wall is a lot of plaster. –  Niall C. Feb 28 '13 at 19:44
    
uhm... do they have stud framing + drywall + fiberglass insulation in your country? –  amphibient Mar 1 '13 at 16:13
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3 Answers 3

I can second XPS or EPS foam but poly (as an absolute barrier) is a bad idea, because the water vapor must be able to move.

You should not try to stop vapor infiltration. The impermable layer must be outside the wall, with a drainage plane between it and the barrier. See Joesph Lstiburek Building Sciences corporation report from 2006 entitled "Understanding Basements"

Understanding Basements

Part of your heat loss is also through the floor, so anything that provides a thermal break will help. That's the problem with using plaster, it is very similar to concrete, AFA thermal transfer goes. Plus, that much plaster won't hang on the wall by itself, it would need a lath sub structure.

Your goal of energy saving would be best accomplished with a XPS foam panels, doing a wall at a time as your budget permits.

Dow Wallmate is a XPS foam panel that is 2'x8' with a cutout for a 2 x 4 stud 1x3 furring strip on the flat. It provides thermal insulation and a logical spot to screw down a drywall covering

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For a flush fit, the channel is sized for a 1x3, not that it matters much. It is a clever system. I agree... apply insulation as budget permits. It took me 6 years to finish my basement walls. We looked at a mix of raw concrete walls and insulation boards and furring strips for a LONG time before it was finally finished. Having to shuffle crap around to access a new section was the biggest cost of all :( –  bcworkz Feb 28 '13 at 22:40
    
+1 very informative report after the link –  mac Mar 1 '13 at 15:20
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According to Bon, plaster has an R-value of about 0.12/inch, so your plan will give you about 0.24. That little insulation is not going to be of any practical value (R-0.24 means you're stopping about 4% of the heat transfer). Comparatively, EPS or XPS has a value of 3.5-5/inch (stopping 72-80% of the heat transfer) and will help with keeping things warm.

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I don't think plaster is going to provide you any reasonable level of insulation. You also have to think about how you'll deal with moisture which will destroy the plaster. Normally there would be some sort of vapor barrier (either XPS foam against the brick or a poly barrier behind the drywall/plaster).

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