How to Replace Floor Trusses

Floor trusses are manufactured semi-rigid structural floor components that take the place of traditional floor joists to provide a stronger support structure for your wood framed floors. Trusses are made to measure, created as a braced frame that’s nailed into place. While floor trusses can last for decades without sag or rot, they can become damaged and need replacement. Though the general structure of the truss is different from that of a floor joist, the replacement process is much the same, requiring the removal of the existing truss followed by the anchoring in place of the new truss. Once the new truss is in place, the floor should once again be as strong as it was before any damage occurred.

Things You'll Need

  • Tape measure
  • Reciprocating saw with metal blade
  • Pole jacks
  • 8d nails
  • Hammer


    • 1

      Access the space beneath the floor truss, either through a basement or a crawl space to locate the damaged truss.

    • 2

      Measure the length and width of the old truss with a tape measure and order a replacement truss of the same size.

    • 3

      Remove the floor truss that you’re replacing by cutting through the joint along the edge of the truss where it connects to the wall with a reciprocating saw containing a metal blade to cut through the nails.

    • 4

      Raise the new floor truss into position using a pole jack on either end to steady it against the subfloor above and against the bordering walls.

    • 5

      Nail the new truss in place using an 8d nail and hammer through both the top and bottom flange of the hoist and then through the center of the end block. If the floor joist overlaps an interior load bearing wall, then use multiple joists, butted end to end at the center of the wall. Nail the two trusses together by toe-nailing an 8d nail through the top of one truss and angled into the side of the top flange of the second truss. Nail the two to the top of the wall by driving an 8d nail through the bottom flanges of each truss into the top wall plate.

Tips & Warnings

  • Do not attempt to repair or modify trusses on load-bearing walls if you have little to no experience. Improper replacement can lead to structural damage to your home.
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