Strengthen Floor Joists From Above

Choose ring shank nails or screws that are long enough to penetrate the joists by 11 2 in and space them every 6 in.

Strengthen floor joists from above.

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. Nailing two 2x4s together will work to span about three joists unless the sag is under a weight bearing wall. Tack a beam under the sagging joists. Jacking them up too fast may cause cracks in the walls and floors overhead.

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. A day until they re level. Lay the new sheets perpendicular to the floor joists and orient panel ends over joists.

You can however strengthen the joists by securing another length of wood to the existing joist called sistering. As incremental parts of a building s structure joists are not easily replaced. The nice thing about a beam and.