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CC over foil covered fiberglass in ceiling Post New Topic | Post Reply

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jeff henderson
Posted: Mar 03, 2009 09:10 PM
CC over foil covered fiberglass in ceiling
I have been asked to spray 3" of 2lb CC on the interiour/warm side of existing foil covered insulation in a workshop. The existing insulation is well secured with strapping - was concerned though about how well the foam will adhere. I haven't done a test section yet - thought I would post first to see if I should have the contractor tear it down first, or not to worry about it.

Any thoughts?

Have I mentioned how much I like this forum?!
mason
Posted: Mar 04, 2009 07:28 AM
I don't recommend spraying foam (open or closed cell) over fiberglass batts with or without vapor retarders. The fiberglass would not prevent water intrusion into the wall or ceiling cavity, but the foam would stop it. So if there is a roof or window leak, you could have a totally saturated fiberglass batt that cannot be dried out. Plus you have a vapor retarder in the middle of the insulation, not recommended.

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