I am having a contractor pour a patio on the rear of my 2-story home, that goes from the rear foundation of my home out 12' , and spans the entire back of the home - 39'6". After the concrete cures, I will build a free-standing cover (I have brick veneer) that is supported by 6X6X8 PT posts on the distant corners. I would like to have only two posts equidistant from each other and the end posts (on both long-sides of the patio - one 8' high, the other 10')). That configuration would create three spans a little over 13' each. I am putting up 2X8 roof rafters (16" O.C.) to go the 12+' distance. Would a double-header 2X10 do the job at both ends of the rafters? I live in the Dallas area, so there is no snow load to consider. I have been looking for a table that takes into consideration doubling up the headers, but I have been unsuccessful. I can go to a 2X12 if necessary, but I want to do it right. I will try to upload a drawing to better illustrate my plan...
I realize my drawing indicates 5 posts across the "front" off the patio, but the same spans cause a post to do right down the middle of an existing window. I'd rather do the front (shorter) header arrangement like the rear and use only 4 posts.
