Strengthen Floor Joists From Above

Nailing two 2x4s together will work to span about three joists unless the sag is under a weight bearing wall.

Strengthen floor joists from above.

Jacking them up too fast may cause cracks in the walls and floors overhead. Tack a beam under the sagging joists. The joists are quite small 5 5 inch x 2 5inch with tiles above so i would also to take this opportunity to strengthen the floor as i think we re borderline on the deflection front and i dont fancy doing the floor again. The nice thing about a beam and.

Strengthening attic joists for live loads by sistering if the attic joists are not adequate one way to strengthen the floor for live loads is to sister the old joists. Choose ring shank nails or screws that are long enough to penetrate the joists by 11 2 in and space them every 6 in. Lay the new sheets perpendicular to the floor joists and orient panel ends over joists. Set a hydraulic jack and post under the beam and jack up the joists about 1 8 in.

To keep the walls above from cracking and to prevent other damage the joist sag is lifted a tiny bit at a time usually no more than 1 4 inch every few weeks. As incremental parts of a building s structure joists are not easily replaced. You can however strengthen the joists by securing another length of wood to the existing joist called sistering.