I have a covered deck that is 10 ft x 18 ft and is 8 ft above the ground. It is covered with a hip roof. It is supported by three 4x4 posts. I want to put a ceiling on the roof of the deck but I am concerned about the support posts. Should they be 6x6 posts instead of 4x4 posts? The three posts are currently about 8.5 ft apart. The beam is a 4x 10 and the joists are 2x10 on 24 inch centers. The decking is 2x6 lumber.

Its little lean here on using4x4s to begin with on that height. The 8' warp/bow factor is the issue here. I would have angled braced the 4x4 to cut down in shear. Its hard ro crush a post straight down, but the sideways shear movement is what most failures are from. or lack of good ground support and things sink.

What kind of ceiling are you putting in?
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