This sounds right, use #30 felt, not the 15. It will basically be a hot roof since it won’t be vented unless I put in baffles. Quoting: AKfisherI was thinking a 1/2 plywood sheathing and then felt, then the concealed fastener roofing panels. However if the roof is not well insulated sometimes snow will melt a bit and then freeze as the temps get colder. I know there is a belief that with a 12/12 pitch and metal, the snow will slide off and not be piling up. Another reason to upsize the rafters when dealing with high snow loads. With a 2 foot eve overhang the rafter tail loads can be high enough to stress the rafter, especially with the birdsmouth notch out. Knowing the species to be used, grade etc will permit more accurate results. A weather barrier, tar paper or a tyvek like synthetic would be used o the sheathing and the metal on that. Metal can be installed on sheathing, no purlins needed, although I know some folks like them. Sheathing- osb or plywood- 7/16 is okay, but 5/8 gives more for the roof fasteners to bite into. But, will the roof be insulated in the rafters or in a flat ceiling? 2x8 do not have much room for insulation. 2x8 can work, depending on species, grade, etc.
#Rafter spacing for metal roof android
Here is a screenshot from the AWC calculator android app. What is the snow load? If you don't know that, what is the nearest town?Ģx8 at 12" would have to be SS Select for both species. Quoting: AKfisherWhat should my rafter spacing be if I plan on a 12/12 pitch and 2x8 common lumber?