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Hot Roof

CliffordC's Avatar

Join Date: Nov 2010
Posts: 1

11-09-10, 04:37 PM   #1  
Hot Roof

I'm in the middle of remodeling a bathroom and need to decide on insulation. The roof is cathedral with a 10 degree pitch. The roof deck itself is rubber membrane. The roof has no ventilation and the ceiling joists themselves have blocking about every 12 feet or so creating closed areas. From what I've been reading, this sounds like a good example of a hot roof.
My main question is whether to use closed or open cell foam in this area. I keep reading that closed is better in this kind of situation. Does the fact that it's a bathroom and the roof is rubber have any affect on a choice?

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drooplug's Avatar

Join Date: Aug 2009
Posts: 4,940

11-09-10, 05:21 PM   #2  
I can tell you that closed cell foam with a thickness of 2" or more will be a vapor retarder where as the open cell foam would not. You want to keep as much moisture away from your roof deck as possible especially in a bathroom. Make sure you have a good exhaust fan as well. I put my fan on a timer so I can set it to run for 30 minutes after my shower and it will shut off by itself.

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