# Rim joist insulation with stone foundation, brick/block house



## indigo (Dec 14, 2009)

Hi there,

House built in the 20s -- basement is partially finished. 

Front and rear areas have completely open ceilings and do not have framed exterior walls and will remain that way. There is a center section which is "finished" with framed exterior walls. Currently its ceiling is also down making everything accessible -- not getting into the insulation (or lack thereor) in those walls just yet.

House has a stone foundation and then the outside walls are all terra cotta block with a brick veneer. 

I am looking to begin the process of air sealing and insulating the basement. I am planning to start in the rim joist area. 

Step 1: I am thinking is going to be hitting all the openings with some canned spray foam, sealing around all the misc penetrations, obvious gaps, etc. 

Step 2: Adding a layer of insulation in these spaces seems to be the thing to do. A decent chunk of the basement will ultimately not be finished, so while I've seen extensive mention of XPS, that would need to be covered. I would prefer to use roxul. 

What R-value would be reasonable? I've got about a 10" deep pocket. I am in Pittsburgh, PA.

Thoughts on vapor barrier? My understanding of the push for XPS is that it also serves as a vapor barrier -- will the roxul + the spray foam effectively accomplish this? Or should I be looking to further seal the areas.

Thank you!


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## Windows on Wash (Aug 30, 2011)

XPS will serve as vapor barrier. 

Post up some pictures and air seal will be critical here with a stone foundation. 

2" of insulation would be the way to go.


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## indigo (Dec 14, 2009)

Windows on Wash said:


> XPS will serve as vapor barrier.
> 
> Post up some pictures and air seal will be critical here with a stone foundation.
> 
> 2" of insulation would be the way to go.


Two pics attached, the first is of where the joists intersect the foundation wall and you can see the terra cotta block - some foam from a previous owner is evident.

Second is where joists are running parallel to the wall -- only a perimeter joist is view-able, block is hidden behind. 

Front 2/3 of the house joists run the width on the house, last 1/3 they run length-wise.


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