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I'm restoring my childhood home and am considering changing to a conditioned attic. There's no drywall on the ceiling yet and I've already installed radiant foil on the bottom of my rafters. The attic is currently vented through the soffit and gable ends. (We had an attic fan.)

I ran across a good deal on 2" polyiso foam board and am wondering if I can add the polyiso directly to the bottom of the rafters over the foil. My thought was to insulate the bottom of the rafters, seal the top plates and install a ductless system for climate control in the attic. I'm located in SE Texas. Hot and humid 9 months out of the year.

isherwood
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Newland
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Radiant foil needs space or it's ineffective.

If you had radiant foil in vented space between rafters, so air space ramained when you installed rigid foam, it would do something. If you touch it with another layer, it does pretty much nothing.

You'll need to change to a ridge venting scheme working with your soffit vents with the vent space between rafters, if insulating the bottom of the rafters to make it conditioned space.

Ecnerwal
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