Another flat roof retrofit insulation question – Zone 6A
Hi all
我有一个约6000平方英尺的公寓roof with TPO membrane over an old EDPM membrane. I believe there’s about 2″ of rigid foam on top of plywood. 2×10 12″ spaced joists and very little slope, and interior insulation in two forms: one part of the house has 3″ rigid foam attached to the joists but no insulation between them, the other just fiberglass batts between the joists with an underside poly sheet.
Assuming I can only work from the ceiling side, because I can’t afford re-roofing such a big roof, what’s are good options? I’m worried that properly insulating the interior will cause problems because of the low exterior R-value (per the article on low slope roof insulation). I’m not quite able to gut the whole ceiling at once, but I will be able to disassemble it in parts as I redo individual rooms.
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Replies
RK2,
I will ask a question to give your post a bump. Have you read Martin's article on insulating a low-slope residential roof (//m.etiketa4.com/article/insulating-low-slope-residential-roofs)?
Yes, I did read that. I will not be able to meet the above-sheathing rigid insulation level. With that, what's the best approach for adding insulation from below, if it needs to be done room-by-room? One thing that isn't clear to me is how important is it for moisture control to have closed-cell spray foam "bond" with the sheathing, compared to for example adding rigid board between the joists.