# Basic Wall insulation in basements



## Soarelp (May 10, 2015)

Good morning everyone,

I hope you guys can help me because I've been looking for this answers for quite long time and amazingly I'm not able to find a direct answer.

I'm from Brazil, but I'm leaving in US- Michigan, Thermal zone 4 &5, now and we decided to finish our basement. I'm working with a contractor who framed my walls, did the electric part and gave me the tip to do the insulation myself in order to save some costs.

And that's the issue I'm having right now, when I started studying about the topic I realized that the majority of the good experts recommend to use a foam closed cell board direct in my concrete wall, before the frame stage. In order to stop the humidity to move towards the dry wall.

I talked about that to the contractor and, off course he start shouting saying that my basement is very dry, but I know, and we don't need to be an expert, that the dryness of my basement is coming from the fact that moisture is been evaporated to the ambient giving such an impression. However my basement has never had any issues with water so far.

So my question would be, what should I do to have the best possible solution in my basement? My studs are ~1in distance from the concrete wall without any vapor barrier or insulation applied yet between them. My contractor told me that using fiber glass between the studs I would be just fine, but I'm afraid of mold and rottenness in a mid long term. I saw that I could use sprayed foam, but is this really the only way?

Please help to figure it out how to proceed. I can't find a reasonable solution in the internet. showing risks and costs related aspects.

Kind Regards


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## Windows on Wash (Aug 30, 2011)

Morning. 

Monday morning quarterbacking would say that rigid board should have been put up first prior to the walls being studded out. 

That being said, no reason that you still can't get it done right and you need not listen to your contractor if he chews your ear off about this. A good framer or GC doesn't always make for a guy/gal that knows building science. 

Easiest way to get it in there and cleanly done is going to be SPF at this point. 

http://apps1.eere.energy.gov/buildings/publications/pdfs/building_america/measure_guide_basement_insul.pdf

Code for your area: https://energycode.pnl.gov/EnergyCodeReqs/?state=Michigan


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## ddsrph (Nov 23, 2013)

If you have a one inch space between studs and block could you not remove about three studs from each wall and then slide one inch XPS blue board behind studs, then replace the three studs?


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## Olcrazy1 (May 28, 2013)

Even if it's dry, once you close in with drywall you will get moister between the block and the drywall. Foam boat should have been done before studs. Although the simple and bast answer in my opinion is spray foam. Blow in from rim joist to floor at 2" thick. Way better than fiberglass or foam boards, no seams plus great vapor barrier. Most air leaks happens in rim joist and spray foam will seal those up as well. Best option in my opinion.


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## Gary in WA (Mar 11, 2009)

Welcome to the forum!

XPS is the "bullet-proof" way but not the only way. Frame/latex may work for you; http://www.buildingscience.com/docu...ing-hygrothermal-modeling-basement-insulation

ADA the drywall to prevent basement air communicating with the cold concrete wall; http://www.buildingscience.com/documents/information-sheets/air-barriers-airtight-drywall-approach/

Foam board (foil-faced XPS) the rims;http://www.buildingscience.com/documents/information-sheets/critical-seal-spray-foam-at-rim-joist

Foamboard under the wall bottom plate- oops- too late.... 

Gary


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