# Insulating basement walls



## bryanp22 (Nov 2, 2011)

I'm debating just painting the cinder block walls or framing them. Any thoughts on if my basement will always just be cold unless I insulate? Anyone just paint the cinder block walls in the zone 6 climates and not have a really cold basement?


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## GBrackins (Apr 26, 2012)

bryan,

would be best to start your own post as questions and comments tend to become confused between two different situations. also you may want to edit your profile to include your location as location determines the best approach to your question


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## Windows on Wash (Aug 30, 2011)

You can just heat the daylights out of the basement and not insulate. At the end of the day, you will have a warm basement but you are going to pay for it.

The benefit to insulating the basement properly is that you are impacting the state and efficiency of the basement for the life of the structure. 

If you are trying to make the basement livable and comfortable, I would suggest that you insulate as mentioned previously. It will be more expensive but it will be a one shot deal and you are done if you do it properly.


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## bryanp22 (Nov 2, 2011)

My house has cinder block walls. If I frame the walls do I need to space them out from the block? Is rigid pink foam best for basements? Any idea on thickness requirement for Wisconsin?


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## Windows on Wash (Aug 30, 2011)

XPS is best for basement wall because it is moisture insensitive.

In Wisconsin, minimum 1", frame the walls out, and unfaced batt insulation.

Seal up the rim joists while you are in there.


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## bryanp22 (Nov 2, 2011)

Do you still have to put in a moisture barrier between the studs and the cinder block then?


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## brockmiera (Oct 9, 2012)

bryanp22 said:


> Do you still have to put in a moisture barrier between the studs and the cinder block then?


Your foam board serves as a thermal break meaning that is keeps condensation from forming because warm air wont ever get to the cold surface of your basement walls. No additional vapor barrier is needed.


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## bryanp22 (Nov 2, 2011)

So the foam goes between the cinder block wall and the studs and I end up with a continuous layer of foam before I put up the studs? For some reason I was thinking you'd have to use it like normal Fiberglas insulation and it would go in the channel between the studs after the wall is framed.


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## brockmiera (Oct 9, 2012)

bryanp22 said:


> So the foam goes between the cinder block wall and the studs and I end up with a continuous layer of foam before I put up the studs?
> 
> Thats correct. You will also want to tape the seams foam seal the top and bottom, fire block as necessary, unsulated and air seal the rim joist.


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## Trucon01 (Jan 10, 2012)

Here's a quick pic of what I'm in the process of if you need a visual.


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## Gary in WA (Mar 11, 2009)

You would lose a lot of heat by not insulating; http://www.quadlock.com/technical_library/bulletins/R-ETRO_Value_of_Basement_Insulation.pdf

With 1" foamboard (R-5 XPS) only and 70*F in room temp, 84% heat reduction and 81% Relative Humidity.

R-5 + R-13 cavity insulation = 95% heat reduction and safe up to (only) 26% RH in room.

R-10 + R-13 ins. = 97% heat reduction and safe to 36%RH. 

Gary


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## HomeSealed (Jan 3, 2008)

Good advice above. 1.5" Xps is used most often. Depending where you are in Wi, you might be eligible for rebates on that work through the Focus on Energy program ( through WE energies). They subsidize 33% of the work up to $1500 if you meet their guidelines


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## bryanp22 (Nov 2, 2011)

I'm in milwaukee area. So you do 1.5 rigid and then rolled in the walls? Do I need to worry about moisture at all with the rolled insulation if I do the 1.5" of rigid foam?


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## bryanp22 (Nov 2, 2011)

Also where can I read requirements of We energies program? I can't seem to find it.


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## HomeSealed (Jan 3, 2008)

There is always SOME worry about moisture in a basement, but the best methods as described will mitigate those chances substantially. Here is the link to the program: http://www.focusonenergy.com/residential


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## Gary in WA (Mar 11, 2009)

bryanp22 said:


> I'm in milwaukee area. So you do 1.5 rigid and then rolled in the walls? Do I need to worry about moisture at all with the rolled insulation if I do the 1.5" of rigid foam?



R-7.5 (1-1/2" of XPS) and R-13 will give f.b. temp of 38*F and 31%RH. If relative humidity is above 31% in the basement at 70*F, it could condense there. You need to realize that if the drywall is completely air-sealed; electrical outlets, caulking, f.b. under the bottom plate with a bead of caulk, rim joists air-sealed, rigid f.b. glued with compatible adhesive in 1' grid squares, cavity insulation touching f.b.- no air gaps at all, you will be fine; http://joneakes.com/jons-fixit-database/743
Basement vapor barrier; https://docs.google.com/viewer?a=v&...Foimib&sig=AHIEtbQYAZ0SWjnVJNXhfHFsk1RrK9G2HQ

http://www.buildingscience.com/documents/information-sheets/air-barriers-airtight-drywall-approach/
Fire-stop every 10' per code.

Gary


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