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wendortb · 08-23-11, 11:21 AM

I wasn't sure if I could do a hot roof. Looking at some case study on unvented roofs, it looks like for my area (closest is chicago with light metal roof) I would need 2" closed cell spray foam to keep the moisture from collecting on the underside of the roof. Cellulose would gather too much moisture according to that.

If I am wrong, I would love to hear so, I could get an r26 cellulose without any rigid foam and not have to bring my ceiling lower, or with rigid foam i could get R31.

The only other option I have seen for an unvented roof is to have 1/3 of the insulation(rigid foam) on top of the roof decking. I don't have anywhere near this and it is too difficult to add.

08-23-11, 11:21 AM	#3
wendortb Lurking Renovator Join Date: Aug 2011 Location: Indiana Posts: 14 Thanks: 0 Thanked 0 Times in 0 Posts	I wasn't sure if I could do a hot roof. Looking at some case study on unvented roofs, it looks like for my area (closest is chicago with light metal roof) I would need 2" closed cell spray foam to keep the moisture from collecting on the underside of the roof. Cellulose would gather too much moisture according to that. If I am wrong, I would love to hear so, I could get an r26 cellulose without any rigid foam and not have to bring my ceiling lower, or with rigid foam i could get R31. The only other option I have seen for an unvented roof is to have 1/3 of the insulation(rigid foam) on top of the roof decking. I don't have anywhere near this and it is too difficult to add.