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Insulating interior concrete walls?

marksland

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Nov 8, 2014
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Central Mass
Starting to chip away at the interior of my new garage and looking for advice or feedback on whether to insulate the interior of the concrete which is mostly below grade? I already insulated the exterior of the foundation with R-10 foam board.

My plan was to glue Owens Corning foam board directly on the concrete, secure with furring strips then cover with ProSlat wall system. I am planning to spray closed cell foam in all the framed portions of the garage (walls and roof line) and then blue board and plaster those areas.

Advice or feedback?
 
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NUTTSGT

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I installed 2x4s flat, IIRC, on the back wall of my garage and put the foam between them. I never glued it to the wall and glad I did when I took it down to pour a new floor. I tapp conned the 2x and covered it with OSB.
 

Chris705

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If you are bringing in a spray foam contractor to do your other walls I would suggest furring out your block walls and foaming them as well. I think it would be very cost effective. Maybe even use metal z furring or stay with wood. Just a thought. Air seal it all up.
 
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marksland

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Central Mass
i looked at the option of spray foam and its actually much cheaper to use the foam board. My thought was foam board joined together against the concrete (to form a complete moisture barrier) and then anchor to the concrete wall with furring strips. If I were to frame the wall first and then add foam in each bay I don't think I would have as good a seal?
 

Voi

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Western South Dakota
Starting to chip away at the interior of my new garage and looking for advice or feedback on whether to insulate the interior of the concrete which is mostly below grade? I already insulated the exterior of the foundation with R-10 foam board.

My plan was to glue Owens Corning foam board directly on the concrete, secure with furring strips then cover with ProSlat wall system. I am planning to spray closed cell foam in all the framed portions of the garage (walls and roof line) and then blue board and plaster those areas.

Advice or feedback?

So is the entire foundation already insulated on the exterior? Or do you mean just the above (or below?) grade portions are?

My garage is mostly below grade and when I purchased the home I considered just gluing rigid foam directly to the interior poured concrete walls (mine has no exterior foam either above or below grade).

I ended up framing the entire interior of the garage out with typical 2x4 walls with a slight air space behind and then ran electric and fiberglass insulation and then drywall.

I go back and forth as to whether the space loss of the framing was worth it for running electric or for the flexibility it gave me for hanging cabinets, which I seem to move around somewhat often.

I think if I were to do it again I'd just go with the foam and install some sort of French cleat system for all of my hanging needs. Electric in surface mount conduit.

Also, I considered using a slat wall system instead of drywall in portions and it was suggested to me that might not meet code for fire rating since my garage is attached. I didn't look into it any further and used drywall.
 
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marksland

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Nov 8, 2014
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Central Mass
So is the entire foundation already insulated on the exterior? Or do you mean just the above (or below?) grade portions are?

My garage is mostly below grade and when I purchased the home I considered just gluing rigid foam directly to the interior poured concrete walls (mine has no exterior foam either above or below grade).

I ended up framing the entire interior of the garage out with typical 2x4 walls with a slight air space behind and then ran electric and fiberglass insulation and then drywall.

I go back and forth as to whether the space loss of the framing was worth it for running electric or for the flexibility it gave me for hanging cabinets, which I seem to move around somewhat often.

I think if I were to do it again I'd just go with the foam and install some sort of French cleat system for all of my hanging needs. Electric in surface mount conduit.

Also, I considered using a slat wall system instead of drywall in portions and it was suggested to me that might not meet code for fire rating since my garage is attached. I didn't look into it any further and used drywall.

I insulated all the portions of foundation that were backfilled (entire right side and rear wall). I could frame out the walls like you mention but I'm trying to maximize my open space, granted a few inches wouldn't be a huge deal of lost space. I like the idea of foamboard for for the fact its both an insulator and vapor barrier, which saves me that extra step. I think where my build is not attached to my house I should be ok with Proslat as a sheathing, especially where its only being used on the lower half of two walls.
 
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evildky

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Louisville, KY
I insulated the block foundation walls of my house in the crawlspace using foam board and an impact hammer on the inside
 

Voi

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Western South Dakota
I insulated all the portions of foundation that were backfilled (entire right side and rear wall). I could frame out the walls like you mention but I'm trying to maximize my open space, granted a few inches wouldn't be a huge deal of lost space. I like the idea of foamboard for for the fact its both an insulator and vapor barrier, which saves me that extra step. I think where my build is not attached to my house I should be ok with Proslat as a sheathing, especially where its only being used on the lower half of two walls.

There have been threads that discussed leaving concrete walls exposed when the exterior side was insulated so one could take advantage of the thermal mass of the wall.

But in your case it sounds like the entire exterior isn't insulated so you're likely to have some thermal bridging even if you only insulated the portions of the interior walls that weren't insulated on the opposing exterior side.

Could you sketch up the footprint of your garage and show which walls have exterior insulation and which interior walls are cold or feel most cold?
 
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marksland

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There have been threads that discussed leaving concrete walls exposed when the exterior side was insulated so one could take advantage of the thermal mass of the wall.

But in your case it sounds like the entire exterior isn't insulated so you're likely to have some thermal bridging even if you only insulated the portions of the interior walls that weren't insulated on the opposing exterior side.

Could you sketch up the footprint of your garage and show which walls have exterior insulation and which interior walls are cold or feel most cold?

The walls that I'm thinking of insulating the interior of and that are insulated on the exterior are the taller walls shown in the first photo. Its the rear wall and the right side wall. These are the most cold, the front wall and left side wall are only concrete stub walls. I hope this helps give a better picture of what I'm working with.
 

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Voi

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I hope this helps give a better picture of what I'm working with.

That's a nice looking garage and nice looking property. Do you have a build thread?

It looks like you don't have a complete thermal break on the outside so I think insulating on the interior as planned is a good idea.

Here is an article about basements but I think it's relevant to your situation. Some conversation in the comments about insulating both sides of a basement wall as well.

Also info about protecting XPS above grade in case you wanted to add more.

http://www.greenbuildingadvisor.com/blogs/dept/musings/how-insulate-basement-wall
 

willymakeit

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Apr 27, 2009
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Springfield Mo.
Looking at the pictures seems to indicate the insulation coverage isn't 100%. Also the comment that the walls are cold now.
Exposed concrete is acting as a thermal bridge [siphon]. A laser thermometer or FLIR camera will probably verify this. I would insulate the inside.
 
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marksland

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Nov 8, 2014
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Central Mass
That's a nice looking garage and nice looking property. Do you have a build thread?

It looks like you don't have a complete thermal break on the outside so I think insulating on the interior as planned is a good idea.

Here is an article about basements but I think it's relevant to your situation. Some conversation in the comments about insulating both sides of a basement wall as well.

Also info about protecting XPS above grade in case you wanted to add more.

http://www.greenbuildingadvisor.com/blogs/dept/musings/how-insulate-basement-wall

Thanks for the comments and information. I do have a build thread, you can see it by clicking on my build link under my signature.
 
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