Insulation Question

[grkmec]

I am in the design stage for a new detached garage and part of it is going to be below grade. This is being done for zoning reasons because I can't go over 15' tall roof vs. average grade. So I am going to raise the grade 3 feet so I can get a 18' roof for my 12' tall walls.

So my architect sent me a sketch with 4' tall cement knee walls, which would then have 8' stud wall of 2x6s. My question is how do I insulate the cement knee walls ? My plan was to use 5' of close cell foam in the 2x6 walls but how do I insulate the first 4 feet of cement wall ?

 

[Keith_MN]

I am also planning something similar on one side of my future shop. I was thinking about putting foam insulation on the outside.

 

[ddawg16]

Look up how basements are done.

If I remember correctly, you try to seal the outside against moisture, and if you want to control temps, you insulate the inside.

 

[Bondo]

My question is how do I insulate the cement knee walls ?

Ayuh,...... Use ICF's,.....

Ya form it with the Icf's, pour the concrete, 'n it's insulated,...
With no time wasted tearin' down the formin',.....

 

[stm317]

You can insulate a concrete wall on the outside and the inside using different types of rigid foam insulation. It's commonly done on foundations and basements.

 

[Twodawgs]

I used ICF's. About half of my garage is up 9ft below grade.

 

[polizei1]

Spray a waterproof product on the exterior to seal it and then use ICF or rigid foam.

 

[KELLHAMMER]

This is really a question for your architect. Thats their job. You don't say what part of the world your in. So that would be helpful. I am an architect in the southeast pa. We waterproof our foundations on the outside and apply a drainage board over that. A pipe in a layer of crushed stone at the base of the wall. pipe runs to out-of-grade or to crock with pump. Check out Tuff-N-Dri from tremco barrier solutions. The drainage board has an R value as well.
Then to insulate on the interior, we either use 2X furring or standard studwalls to create a cavity to insulate. You can apply rigid foam directly to the concrete. Fiberglass should get a 1" airspace from concrete. Rigid foam needs to have a layer of gypsum applied over it to prevent the spread of fire. Spray foam is another option but generally more costly. Any foam on the exterior needs to be rated for such use. To avoid moisture absorption, insects, UV degradation etc. We don't tend to use IFC's around here since is it not as economical as poured concrete and there simply aren't that many qualified installers. The single biggest issue for us, is water intrusion, into the space below grade so we tend to design to insure that wont be a problem. Tuff-n-Dri and systems like it are the key.

 

[grkmec]

Thanks guys. Didn't know about ICFs. That's why I love this forum - I seem to learn something new every time I am here. The problem I see though with ICFs is the width compared to a 2x6 stick wall. The thinnest option (R22 version) is 10.25' thick.

http://www.quadlock.com/images/icf_components/R-Values/ICF_Walls_R-Values.png

And then I assume you need to frame it. Even if you use 2x4 on the flat side and 1/2" sheetrock, you are looking at a 1 foot thick wall compared to traditional wood construction. All of sudden my 30' wide garage just turned into 28' width interior.

I assume another option is just to pour 6" cement walls with rebar and then frame inside with pressure treated 2x2s on 24' OC and use 1.5" of closed cell foam. That would give R10 and use up only 8" vs. 12" w/ the ICF.

BTW, I am Stamford, CT.

 

[850xpeps]

Thanks guys. Didn't know about ICFs. That's why I love this forum - I seem to learn something new every time I am here. The problem I see though with ICFs is the width compared to a 2x6 stick wall. The thinnest option (R22 version) is 10.25' thick.

http://www.quadlock.com/images/icf_components/R-Values/ICF_Walls_R-Values.png

And then I assume you need to frame it. Even if you use 2x4 on the flat side and 1/2" sheetrock, you are looking at a 1 foot thick wall compared to traditional wood construction. All of sudden my 30' wide garage just turned into 28' width interior.

I assume another option is just to pour 6" cement walls with rebar and then frame inside with pressure treated 2x2s on 24' OC and use 1.5" of closed cell foam. That would give R10 and use up only 8" vs. 12" w/ the ICF.

BTW, I am Stamford, CT.

No need to frame icfs. We just drywalled a basement no issues screwing through the plastics in the icf form that’s what it’s there for. What I would do though is 1/2”-3/4” plywood instead on it for a garage to hang stuff.

Icf 8’ high an who cares if the wall gets smaller to your 2x6” level after that. It’s a great way to build. You need to build out a cement wall anyway .


Blue skin or another bithuthene membrane on the outside below grade to your wheeping tile system and your done.
Some think Masonite or crappy own can be placed if larger rock are used for backfill to help save blueskin from damage.