Most people say to use open cell foam for attic roof leaks. Could I spray closed cell foam over baffles from soffit to ridge vent?
If I put baffling between the rafters next to the roof sheathing, then spray 3" of closed cell foam, would this eliminate water issues and a hot roof? It seems like a good idea that I had never heard of before from other closed cell contractors. This would in theory create an airspace for molecule movement as well. I just want to know if this is a viable solution for NC climate.
That is a fine option and should work very well.
- Your solution addresses the majority of the concerns of a "hot deck" or unvented attic.
- If you are going to install home foam insulation over the baffles, I would build my own baffles rather than use the cheap foam ones you typically see with fiberglass. The cheap baffles are not rigid enough to withstand the expansion of the foam and you risk closing off your ventilation channel.
I would build my own baffles with either rigid foam or plywood. The rigid foam will also give you some additional R-value. Even better, use a foil-faced rigid foam with a minimum 1" airspace and you have a radiant barrier in your assembly as well.
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