I am planning to build a backyard patio in the next few months and I have come up with the tentative plan shown in the attached pictures. It will be freestanding with the back end overlapping the end of my house roof by a foot or so (just enough to keep the rain out). All wood will be PT pine.
Posts: 6x6x12'L buried 3' deep in concrete spaced 9' OC Front-to-Back and 14' OC Left-to-Right (x4)
Headers: Double 2x12x22'L (x2)
Diagonal Braces: Double 2x8 (x8)
Joists: 2x6x12'L spaced 16" OC
Nailing Strips: 1x4 spaced 24" OC
Roof: 26"W x 12'L Galvanized Steel Panels (x11)
My main concern is the 14' spacing between the posts. Are double 2x12's with diagonal braces sufficient for this span (or even overkill)? Keep in mind I am in south Louisiana so no need to design for a snow load. Only weight will be a pair of ceiling fans. Just looking for guidance at this point so feel free to shoot as many holes in the design as you like.
Also, what would be the best way to attach the diagonal braces to the posts and headers? Brackets or lag bolts?