I have a 10 ft tall 12 ft wide and 46 ft long patio cover that I'm adding to the back side of my house. I have it all supported by 4x4s. They are spaced at about 7 feet apart down the entire 46 ft length but the 12 ft wide from the edge of my house to the edge of the porch has nothing.

I'm going to be putting a metal roof on top of it. Are my 4x4s enough to safely hold this weight? I live in South Alabama so snow is not usually a problem and wind where I'm at is normally not a big problem either.

Also: I used 2x6's for the entire rafter system as well as my main beams holding the weight. I feel like I screwed up on that one. I'm thinking about coming back in underneath the two by sixes and adding another one directly below the ones I already have, just for extra support, or take A 2x4 and lay it flat on my 4x4 and attaching that down the whole length of the 4x4 just so my 2x6's have something to sit on top of in order to stop the shear weight from possibly snapping my screws.

Any info will be greatly appreciated thank you.

  • Put your information in your question, please. It doesn't belong in comments. Take the tour to learn more.
    – isherwood
    Commented Nov 18, 2020 at 20:59
  • A photo would help to clarify your design.
    – Alaska Man
    Commented Nov 18, 2020 at 21:02
  • You did not mention battens perpendicular to your roof rafters to attach the metal roofing to. ?
    – Alaska Man
    Commented Nov 18, 2020 at 21:12
  • You mentioned shearing screws -- usually 16d framing nails would be the correct fasteners for the type of framing you're talking about. That might be a bigger problem than the lumber. Also, the beams shouldn't be hung on the side of your posts; the posts should be notched so the beams can bear on the posts! When you just nail/screw them in, the weakest link is the wood directly surrounding the fastener. It sounds like your structure could use adjustment. :( Commented Nov 19, 2020 at 13:42

1 Answer 1


So 4x4 posts every 7 feet, single 2x6 beams, and 2x6 rafters spanning about 12 feet. Right?

That's all fine except for the beams. They're barely adequate and will probably sag. You don't have to worry about snow loads, but you'll have a wavy roof after a few years.

I'd double them and fasten them together with two screws every 16 inches or so. Don't use a flat 2x4. That does nothing as a board like that is a trampoline.

  • I 100% agree with doubling them as a 4 x 6 would be minimum beam size with that projection and those rafters should be @ 16" O.C. min. if you are roofing it. Commented Nov 19, 2020 at 3:18

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