Closed-cell vs. open-cell spray foam and exterior rigid foam on the roof
Michael Caudill| Posted inEnergy Efficiency and Durabilityon
In climate zone 5 if you use a roof wrap, rigid insulation and a vented area under a metal roof on top of the roof sheathing, then is open cell foam better for the underside of the sheathing since it would allow the roof sheathing to dry out – OR – would a closed cell foam or other vapor barrier still be needed? Thanks.
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Replies
Michael,
If you plan to install rigid foam above your roof sheathing, then open-cell spray foam is a better choice than closed-cell spray foam on the underside of your roof sheathing. If your roof sheathing ever gets wet, the open-cell spray foam will allow the damp sheathing to dry to the interior.
For more information, seeHow to Install Rigid Foam On Top of Roof Sheathing.