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My question is how much load can my 2 each 6 x 6 pre-treated post handle. I have approximately 1,466 lbs of treated wood as my roof of the pergola and it will be attached to the house the other will be 2 each 6 x 6 post in concrete in the ground. I wanted to hang a swing between the 6 x 6 post (350 lbs max weight). My span between 6 x 6 post is 12 ft center to center. I have 2 x 12 x 20 bolted on each side of the 6 x 6 post. I wanted to hang my swing from that.

Will my structure work? Will 6 X 6 post handle 1,466 lbs plus swing 350 lbs? Is this structure design sound for this application? enter image description here

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The 6x6 and the double 2x12 are sufficient in themselves for your swing. But the 2x12s may not be attached securely enough to the 6x6 posts, and/or the pergola may not be attached securely enough to the house.

Also, once the temporary diagonal cross braces on the 6x6 shown in the photo are removed, there may not be enough lateral stability. If you were to convert the pergola into a roof, and sheathed the roof with plywood, then there would be enough lateral stability assuming the framing is attached securely enough to the house.

  • Right. Any post should mostly withstand vertical loading. In this case, you have the potential for massive horizontal loading due to wind. – isherwood Sep 18 '17 at 21:20
  • horizontal loading also from swinging on the swing – David Sep 19 '17 at 17:12
  • That's mostly perpendicular to the house. I'd assume that all those joist attachments would hold up fine. – isherwood Sep 19 '17 at 18:58
  • Agreed. Neglecting goofing around with sideways swinging, mostly perpendicular. I wouldn't take the assumption.of adequate attachment to the house, which likely is primarily for the shear of a vertical load. My main point being that items of concern include more than lumber dimensions and geometry, its the details in the connections too. – David Sep 19 '17 at 19:32
  • In my opinion, it looks framed for corrugated roof panels, but the OP calls it a pergola. It's an overhead structure so probably involves codes/permits, but it it is not a roof but a pergola, so it may not involve either. There is also the issue of the toenailing of the rafters into the pair of 2x12s, and the attachment of the rafters to the ledger/band joist with toenailing or joist hangers. – David Sep 19 '17 at 19:32

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