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ERIK KASUBA Posted: Jan 18, 2010 09:15 PM	Rim Joist : Spray Foam over Rigid Insulation? Hey guys- Right now, I have the "builder special" of fiberglass batts insulation in my rim joist area of my unfinished basement. Before I finish my basement, I would like to upgrade the insulation in this area and prevent air infiltration. My original intention was to cut and place 2" XPS rigid foam insulation and caulk the perimeter. Then I stumbled upon this site.... What do you guys think of still using the 2" rigid foam, and spraying the perimeter with closed cell spray foam instead of using caulk. I like this idea, because I can also spray the sill plate the top of the concrete wall that the plate is not covering. Also, I wouldn't have to pay for 3" deep spray foam at the rim joist. Or would you just spray foam the whole thing and not worry about the labor of cutting the rigid insulation? The total perimeter of the basement is 135' with 2x10 joists. Also, in one part of the basement, they ran the 1/2" electrical conduit pipe on top of the foundation wall next to the sill plate for some of pull chain lights in the basement. Would it be okay to spray foam over this conduit? Thanks for your help.
Gerry Wagoner Posted: Jan 19, 2010 07:33 AM	I would recommend spraying the rim joist pockets with 2.5" closed cell spray foam. Will control thermal loss, and help to eliminate bugs etc. The conduit may be sprayed over. oG
mason Posted: Jan 19, 2010 07:52 AM	Yes you can spray over conduit, and I would agree that spraying the rim joist without the board insulation would be more effective and keep the critters out.
Circle-D Posted: Jan 19, 2010 04:41 PM	Most guys I believe have a minimum charge, I know I do. Just spraying the perimeter would probably not meet the minimum. You would still be paying for a full job. Whether you got it or not would be up to you. Spray the full cavity with 2 1/2" to 3" and get your moneys worth.
richard sucher II Posted: Jan 19, 2010 04:56 PM	given the lineal footage that you list at 10" high and the recommended thickness of 2.5-3.0 inches of closed cell foam, you could consider buying "do it yourself" foam kits to do the job. Two (2) 200 board foot kits would do it. Fire rated foam kits are available. Cost for two kits probably around 800.00 or so. you do the masking, spraying, and clean-up. note: this process can be messy - one good reason why you might want to hire it done. Good luck.
mason Posted: Jan 20, 2010 04:28 PM	Remember when using foam paks to keep the material at the temperatures specified by the manufacturer or it won't work right. Follow instructions very carefully. Expect to have a pretty rough spray pattern and do not apply it too thick in one application (less than 2 inches) and wait 5-10 minutes between lifts. And more importantly, Wear a respirator suited for the application, nitrile gloves and chemical resistant coveralls. Also, mask off everything that you do not want foam on. It will not come off. Or better yet, hire a contractor to do the job. I agree that the set up charge would probably cost more than the application. So, it would make sense to find some other areas to spray. (attic, basement walls, etc)

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Comments

ERIK KASUBA

Posted: Jan 18, 2010 09:15 PM

Rim Joist : Spray Foam over Rigid Insulation?

Hey guys-

Right now, I have the "builder special" of fiberglass batts insulation in my rim joist area of my unfinished basement. Before I finish my basement, I would like to upgrade the insulation in this area and prevent air infiltration. My original intention was to cut and place 2" XPS rigid foam insulation and caulk the perimeter. Then I stumbled upon this site....

What do you guys think of still using the 2" rigid foam, and spraying the perimeter with closed cell spray foam instead of using caulk. I like this idea, because I can also spray the sill plate the top of the concrete wall that the plate is not covering. Also, I wouldn't have to pay for 3" deep spray foam at the rim joist.

Or would you just spray foam the whole thing and not worry about the labor of cutting the rigid insulation?

The total perimeter of the basement is 135' with 2x10 joists. Also, in one part of the basement, they ran the 1/2" electrical conduit pipe on top of the foundation wall next to the sill plate for some of pull chain lights in the basement. Would it be okay to spray foam over this conduit?

Thanks for your help.

Gerry Wagoner

Posted: Jan 19, 2010 07:33 AM

I would recommend spraying the rim joist pockets with 2.5" closed cell spray foam. Will control thermal loss, and help to eliminate bugs etc.

The conduit may be sprayed over.

oG

mason

Posted: Jan 19, 2010 07:52 AM

Yes you can spray over conduit, and I would agree that spraying the rim joist without the board insulation would be more effective and keep the critters out.

Circle-D

Posted: Jan 19, 2010 04:41 PM

Most guys I believe have a minimum charge, I know I do. Just spraying the perimeter would probably not meet the minimum. You would still be paying for a full job. Whether you got it or not would be up to you. Spray the full cavity with 2 1/2" to 3" and get your moneys worth.

richard sucher II

Posted: Jan 19, 2010 04:56 PM

given the lineal footage that you list at 10" high and the recommended thickness of 2.5-3.0 inches of closed cell foam, you could consider buying "do it yourself" foam kits to do the job. Two (2) 200 board foot kits would do it. Fire rated foam kits are available. Cost for two kits probably around 800.00 or so. you do the masking, spraying, and clean-up. note: this process can be messy - one good reason why you might want to hire it done. Good luck.

mason

Posted: Jan 20, 2010 04:28 PM

Remember when using foam paks to keep the material at the temperatures specified by the manufacturer or it won't work right. Follow instructions very carefully. Expect to have a pretty rough spray pattern and do not apply it too thick in one application (less than 2 inches) and wait 5-10 minutes between lifts.

And more importantly, Wear a respirator suited for the application, nitrile gloves and chemical resistant coveralls.

Also, mask off everything that you do not want foam on. It will not come off.

Or better yet, hire a contractor to do the job. I agree that the set up charge would probably cost more than the application. So, it would make sense to find some other areas to spray.
(attic, basement walls, etc)

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