Rigid foam on wood deck with metal roof?
gyberry
| Posted in Energy Efficiency and Durability on
6″ closed cell rigid foam boards (4’x8′) laid on top of wood decking. Use a 6″ metal Z channel @ each 4′ run of foam-horizontally run and screw Z channel on each rafter. Lay metal roof on Z channel and anchor with screws. No attic. Open conditioned area from floor to rafter. Use ductless mini split heat pumps. I thought about a self adhered membrane on wood deck under foam boards or house wrap. Walls will be 2″x4″ with cellulose. What would you recommend? Do you see any problems with this roof design in Mississippi?
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Replies
Guy,
I would check with the manufacturer of the metal roofing (or your roofing contractor) to make sure than metal purlins 4 ft. on center are enough support. I've always used 1x4 or 2x4 purlins, 24 inches on center, under a metal roof.
For more information, see this article: How to Install Rigid Foam On Top of Roof Sheathing.