Insulating Ceiling - Closed-Cell Foam

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Posts: 2
Joined: Sat Jan 18, 2020 10:05 am

Sun Jan 19, 2020 9:38 pm


New to MH ownership and to this forum. I've searched the forum and didn't find answers so i hope i'm not asking a FAQ. 1971 singlewide with bump-outs, original metal roof. Gutted the entire living area (left the two bedrooms alone). Removed the ceiling panels, added gussets to straighten and strengthen the joists, will be strapping, hanging Sheetrock, and plastering. There is a black fiber board of some kind above the insulation that i've read here is to protect the metal from the wood rafters and for sound deadening. Guessing it's not a vapor barrier as there was poly under the rafters. I'm going to have it insulated with closed-cell foam. The fiber board is falling in places and not attached to the roof at all, as it seems. Is it ok to remove the fiber board, leaving the strips above the strapping along the roof for protection (i'm thinking it may be glued anyway, but i haven't looked too closely) and spraying the foam directly onto the metal. If i don't remove it, the foam won't fill the entire cavity leaving a gap between the foam and metal roof which i'm thinking won't be good, and at minimum will limit the amount of insulation and reduce R-factor.

Is this the right approach?

Are these 'attics' ventilated? There aren't gable vents or soffit vents, and there was some black (guessing mold) above the poly but the insulation is pretty clean. So it would seem there is ventilation otherwise i would expect more mold and rot.

Thanks in advance for your responses.


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Posts: 5644
Joined: Wed Feb 28, 2007 8:01 pm
Location: Weedsport, NY

Mon Jan 20, 2020 7:16 pm

I would talk to whoever is applying the foam for their thoughts. Foam is usually considered a thermal break and not a vapor barrier, but since it is airtight it may be considered as one. Ventilation has always been a problem with older manufactured homes like yours, there really are no simple answers.

"If I can't fix it, I can screw it up so bad no one else can either."

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