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Phyllis Anderson Posted: Dec 13, 2011 03:15 PM	Spray Foan on top of batt insulation? We have a ceiling with batt insulation with a plastic backing that's becoming brittle - can spray foam be applied right on top of that to fill in the open area between the trusses? There is at least a 4 inch open area if the foam would adhere to the old surface and fill in between the boards.
Circle-D Posted: Dec 15, 2011 08:34 PM	I wouldn't advise it. The foam will not be sealed to the ceiling as it should and will not do the job intended. You will get a much superior job by removing the old brittle material and spraying directly to the backside of the ceiling. Always cheaper to it right than do it over.
Eric Machemer Posted: Dec 18, 2011 06:39 PM	I concur with Skip. Pull out the pink fluffy stuff and spray foam directly on the ceiling.
Daniel X Posted: Dec 19, 2011 12:18 AM	Bad idea. Not a suitable substrate for a foam application. I can't see a benefit of leaving the crap in there and putting all of that money over a questionable surface. Clean, dry, well fastened, are some of the things you should be working towards for a good substrate.

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Comments

Phyllis Anderson

Posted: Dec 13, 2011 03:15 PM

Spray Foan on top of batt insulation?

We have a ceiling with batt insulation with a plastic backing that's becoming brittle - can spray foam be applied right on top of that to fill in the open area between the trusses? There is at least a 4 inch open area if the foam would adhere to the old surface and fill in between the boards.

Circle-D

Posted: Dec 15, 2011 08:34 PM

I wouldn't advise it. The foam will not be sealed to the ceiling as it should and will not do the job intended. You will get a much superior job by removing the old brittle material and spraying directly to the backside of the ceiling. Always cheaper to it right than do it over.

Eric Machemer

Posted: Dec 18, 2011 06:39 PM

I concur with Skip.

Pull out the pink fluffy stuff and spray foam directly on the ceiling.

Daniel X

Posted: Dec 19, 2011 12:18 AM

Bad idea.

Not a suitable substrate for a foam application.

I can't see a benefit of leaving the crap in there and putting all of that money over a questionable surface.

Clean, dry, well fastened, are some of the things you should be working towards for a good substrate.

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