Sister Cracked Floor Joist

Slip an old work metal joist hanger onto the end of the joist.

Sister cracked floor joist.

If needed notch the bottom edge of the sister joint so it fits over the foundation or beam. Cut a sister joist the same length as the damaged joist. Since this is a repair of a faulty or damaged floor joist it is imperative to do this project correctly and there are a few big mistakes to avoid. Framing lumber or laminated lumber if needed for strength.

Place it next to the damaged joist with the crown side up. Position a 2x4 post and hydraulic jack directly beneath the cracked end of the joist. Structural screws and joist hangers if applicable. Tools materials required.

I recently had to repair a broken floor joist that had cracked. On both sides of the problem area. Fixing broken cracked sagging floor joists. Squeeze a generous amount of carpenter s glue into the crack in the floor joist.

If a crack or sag is isolated to one area the sister joist should extend at least 3 ft. 2 x 4s together to make a cross beam then place the beam perpendicular to the joists near one end of the joists. But it s usually best to run the sister joist over the entire span. Properly sistering floor joists is very important and should not be rushed to save time.

A severely cracked or sagging floor joist can get worse over time causing the floor above it to slope or become unleveled.