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-   -   Basement wall insulation (http://www.diychatroom.com/f19/basement-wall-insulation-76204/)

dandw12786 07-14-2010 11:03 PM

Basement wall insulation
 
Hey everyone,

I'm in the planning stages of finishing my basement. The house is relatively new, and like many other new houses around here, the basement was left unfinished (but studded and insulated) by the builders to keep prices lower for first time homebuyers. I'm stuck on the insulation issue.

My basement walls have two sections. The bottom part is concrete, only about 4 feet or so is underground, and the top is wood. The two sections are separated by a sill that comes about 4 inches in, so it'll be easy to use two different methods of insulation on these sections. I'm fine with using the fiberglass insulation and vapor barrier technique on the top section because it's made of the same material as the upstairs. However, I've been reading lately about using the old fiberglass and vapor barrier technique against concrete basement walls, and how it's not recommended anymore, being a recipe for mold. What would be my best option for the bottom section then? As I said, these walls are already studded, so putting something between the studs and concrete isn't really an option. Thanks for your help!

joe.shrigley 07-15-2010 07:12 AM

you could always look into spray foam, it's a little more pricey than fiberglass but it does have it's benifits as well. Just a thought

behrend 07-15-2010 12:14 PM

Having just lived through a severe mold issue from fiberglass and a walkout basement, spray foam is an excellent answer. Here, it is roughly 2x the material cost of XPS, but is well worth it. My builder framed the wall tight to the block with 2x4. I removed all the 2x4 and replaced them with 2x3 to give a 1" gap that the foam would create a thermal break. He also filled my rim joist boxes with open cell foam. No more mold.

Troglodyte 07-15-2010 01:37 PM

This document can help a lot in understant what to do and why to do it as far as basement insulation goes

http://www.buildingscience.com/docum...-basements.pdf

Leelumberchgo 07-15-2010 02:11 PM

Basement Insulation
 
Another option is a rigid foam insulation, it is sold in 4' x 8' sheets or 16" x 8' sheets and you can get it up to 2" thick.


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