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Roofing/Metal Carport Roof


New freestanding frame 2' OC 12' long 2X4 rafters and end fascia, 2X6 ridge rafter. OSB 1/2" sheathing, 30# felt. Do I need horizontal purlins to install corrugated 29ga roof panels with #9 self tapping screws? Panel coverage is 21.5", double lap. If single lap, 24", could screw directly into rafters. 1X4 purlins? Spacing? In S. AZ, no snow, high thunderstorm winds.

I do finished roofs and not framing but if you install OSB, at that point aren't you saying to yourself that the structure now has a secure deck so you can put stuff on top of it? I don't see why you'd add purlins just because you're adding metal sheets to the deck. The deck is the supporting structure at that point.



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Brad Zacharia


All aspects of residential Roofing. This includes shingles and flat (low slope) roofs. I have knowledge in the installation as well as the design of roofs from an engineering standpoint.


I have been doing roofing for 40 years. This was my father's business and I took it over in 1980.

I have written responses to artcles that I felt needed a response to and those responses have been published in roofing trade magazines.

BSEE Drexel University

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