Sister Cracked Floor Joist

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

Sister cracked floor joist.

Pump up the jack until the post pushes closed the crack in the joist. Tools materials required. Fixing broken cracked sagging floor joists. If needed notch the bottom edge of the sister joint so it fits over the foundation or beam.

Framing lumber or laminated lumber if needed for strength. But it s usually best to run the sister joist over the entire span. 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. 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. Cut a sister joist the same length as the damaged joist. On both sides of the problem area. Squeeze a generous amount of carpenter s glue into the crack in the floor joist.

A severely cracked or sagging floor joist can get worse over time causing the floor above it to slope or become unleveled. When the sagging joists are level apply a generous bead of construction adhesive to the existing joist. If a crack or sag is isolated to one area the sister joist should extend at least 3 ft. Properly sistering floor joists is very important and should not be rushed to save time.

2 x 4s together to make a cross beam then place the beam perpendicular to the joists near one end of the joists.