Long story short I constructed a shed foundation on uneven ground with piers concreted into the ground. This however turned out to be 2” out of square and is a slight rhombus shape - and to correct this I need to gain 2” in opposite corners.

I attempted this with a sort of sistered joint, secured with two coach bolts and two screws at regular intervals. This went okay, however I’m concerned about the load it will be able to take as it will be bearing one of the shed walls. The sistered joint is not sitting on the pier post like the 2x 2x4 it’s bolted to.

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If this is not substantial enough, then my other option is to source longer timber length to achieve the same thing.

Appreciate advice!

  • 1
    Why didn't you just replace those two boards? Would've cost about the same as the bolts. If this post is in response to my earlier suggestion, it's the joist in the middle of the floor I was concerned about. You have a trampoline going there, with the entire contents of your shed resting on one 2x4.
    – isherwood
    Commented Sep 30, 2019 at 22:32
  • Already had the bolts and longer boards are slightly more difficult to source, however if this isn’t suitable I’ll get them replaced. I will double up the middle beam as pointed out. Appreciate the advice!
    – George
    Commented Sep 30, 2019 at 22:49

1 Answer 1


You are correct to worry that the sistered joists connection to the post is weak. What's supporting that corner is the shear strength of the 4 framing nails above the post, the friction of the 2x4s being compressed by the bolts, and the levered shear strength of the bolts. You could improve it by:

  • put a bolt through the 2x4s above the beam.
  • add 2x4 blocking below the 2x4s and nailed to the post
  • add framing angles with structural screws, fastened to the post and the outer 2x4s

Something else I don't see is attachments to keep the 2x4s atop the beams. You most likely want some joist hangers or hurricane ties to maintain that connection.

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