Building a patio cover...span and size of lumber Q's

jongordo8 · 08-28-2009, 09:29 AM

I want to build an outdoor patio cover using wood (either PT or western red cedar) and have several questions. total size will be 16'W x12'D'x ~9.5'H. Basically a pergola with plywood sheating above the rafters, than 15# felt paper, and then shingles.

1) Can someone tell me how to calculate post size for the span I am trying to use....16ft. They will be 12 foot long posts with 2 feet min set in concrete (probably 2.5 feet for proper height), so about 9.5 feet high.

2)How about Beam size for above the posts, beam will be 16ft. It will be attached to the posts using strong-tie post caps.

3) Rafters will be spaced every 16inches OC and will Rafter span will be 10.5ft with the rest of the 12 ft boards as soffitt overhang. (will be attached to ledger using joist hangers and attached above the beam using strong-tie hurricane ties), what size Rafters do I need?

4)What size ledger do I use for a 16' span?

4)What is the proper pitch for rafters that span 12' (how much lower do I set the beam compared to the ledger.

5) Is 1/2" Plywood ok to use of should I go thicker, don't know if that is part of the structure or not.

Thanks in advance. I attached a drawing to make it easier to visualize what I am trying to do.

**Gary in WA** · 08-30-2009, 01:08 AM

This is a covered roof that needs proper footings, hold-downs, shear bracing, calculations and probably a permit. When you sell, the buyer will check your house record at the County for permits and inspections (if required) for your safety.
Be safe, G