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    • #74513

      I am in the process of finishing my basement and there are a 4 joists that were cut in half and then sistered to another board for support. The problem, I’m told, is that the sister boards don’t go from support to support, they are about 1 foot short. I’m told this is in violation of code and needs to be fixed before I close things up.

      I’ve been playing with the idea of just adding a couple half walls as support for the joists, but the more and more I think about that the less I like it.

      Should I replace the joists? Or perhaps add yet another sister board that spans the whole distance between supports? Or should I tear out the exists joists and replace them with something new.

      The builder did this, for whatever reason it passed inspection. And I’m sure replacing the joists is a lot of work, but fortunately at this point they didn’t use much construction adhesive at all so the boards will only be nailed to the subfloor.

      Ideas, suggestions?


    • #304038

      Joists are sometimes spliced or sistered in the manner you describe. Codes vary. If the sistered board extends far enough, and has a frequent nailing or bolt schedule or is bonded and nailed, or uses a rated mending plate, it may be just as strong as an uncut piece.

      You should ask your local building department to confirm the code or consult with a structural engineer in your area and ask whether local code prohibits this, and what to look for in terms of lumber rating and nailing schedule. For a rule of thumb, a proper sister joist must be a minimum of 1/3 of the span of the joist plus the length of the damage that is being repaired. The sister joist should have a triple row on nails every 12 inches on center to properly transfer the floor loads from the damaged joist to the sister joist. Bolts are better, and using construction adhesive with bolts or nails is very strong.

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