Patio cover structural advice please.

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Just looking for some advice on a patio cover idea I'm tossing around and would appreciate comments by those in the know.

The amount of my patio to be covered is 16'x21'. This will be an attached (via ledger board) patio cover and extend away from the house to cover the 16' width. My plan is for 2x8x16s for the rafters on 16" centers. They will span 14' or 15' with a 1' or 2' overhang. Roofing will be thin enamel coated metal roofing panels - not OSB and shingles.

The snow load requirement is 30psf. I've talked with the city inspector and he indicated since it is not a habitable structure, the code requirements are sparse and even the snow load may or may not apply to it. He simply said to submit my plans and if they don't "look stupid or dangerous", then I should be good to go. This didn't really answer my concerns as I was looking for actual guidelines to follow with my rafter and spacing choice. It seems every online calculator I find is for habitable buildings.

Do you think 2x8x16s on 16 inch centers is sufficient to be safe/solid and not sag when spanning 15' or 16'? Is this overkill? Underkill?

Thanks!
 
I built nearly the same roof over my patio in NJ, mine being 20'x14' and connected with joist hangers to a 2x10 ledger board bolted into the house studs. The beam was two 2x8s lag bolted into four 4x4 posts spaced 6'8" apart. My joists were 14' lengths of 2x8s which overhung the beam by 1'. Joist spacing was 24", which was approved in the permit application and by the inspector. I used 3/8" plywood with shingles, but if I were to do it over again I would use 5/8" plywood so as to avoid the slight sponginess when walking on the roof.

My patio roof is still solid as a rock after 12 years, and even survived a direct hit from Super Storm Sandy, which blew two tall pine trees onto the roof. If anything it sounds like your plan for 2x8x16s rafters on 16" centers is overkill, but then the added expense and effort for a more solid structure is minimal.

If you have a program that can open a Lotus 123 file I can sent you my plan.

Tom NJ
 
Thanks for the insight. I think Excel will open a Lotus 123 file, so I'd love to see your plan!
 
Originally Posted By: 28oz
Thanks for the insight. I think Excel will open a Lotus 123 file, so I'd love to see your plan!


No unfortunately Excel does not open a Lotus file. I can save it as an Excel file but it loses some features. Still it may be useful, so if you PM me your email address I'll send it along.
 
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