Sister Cracked Floor Joist

Place it next to the damaged joist with the crown side up.

Sister cracked floor joist.

When the sagging joists are level apply a generous bead of construction adhesive to the existing joist. Fixing broken cracked sagging floor joists. A severely cracked or sagging floor joist can get worse over time causing the floor above it to slope or become unleveled. Structural screws and joist hangers if applicable.

Properly sistering floor joists is very important and should not be rushed to save time. 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. If needed notch the bottom edge of the sister joint so it fits over the foundation or beam.

On both sides of the problem area. Squeeze a generous amount of carpenter s glue into the crack in the floor joist. 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.

I recently had to repair a broken floor joist that had cracked. Tools materials required. 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.

Pump up the jack until the post pushes closed the crack in the joist.