Sister Cracked Floor Joist

If needed notch the bottom edge of the sister joint so it fits over the foundation or beam.

Sister cracked floor joist.

I recently had to repair a broken floor joist that had cracked. Squeeze a generous amount of carpenter s glue into the crack in the floor joist. Pump up the jack until the post pushes closed the crack in the joist. 2 x 4s together to make a cross beam then place the beam perpendicular to the joists near one end of the joists.

Place it next to the damaged joist with the crown side up. 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. Structural screws and joist hangers if applicable. Tools materials required.

On both sides of the problem area. Properly sistering floor joists is very important and should not be rushed to save time. But it s usually best to run the sister joist over the entire span. Position a 2x4 post and hydraulic jack directly beneath the cracked end of the joist.

If a crack or sag is isolated to one area the sister joist should extend at least 3 ft. Cut a sister joist the same length as the damaged joist. When the sagging joists are level apply a generous bead of construction adhesive to the existing joist. Framing lumber or laminated lumber if needed for strength.

Fixing broken cracked sagging floor joists.