Leveling New Floor Joists

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

Leveling new floor joists.

You just have to make sure that the joists can handle the addition of more weight from the plywood subfloor and any additional floor coverings. Even though we use 1 pt lumber the joists are often slightly warped or vary in depth at times causing adjacent joists to differ in height by as much as 1 2 inch or more. Use screws to secure the leveling strips to the floor every 16 inches. You can also lay down new hardwood floor on the top side of the floor.

Set a hydraulic jack and post under the beam and jack up the joists about 1 8 in. Setting the joists perfectly level at the house is easy and the beam makes them fairly even near the front edge but the problem is in the middle. Usually when a joist gets sistered the new lumber does not span the entire length of the old joist. Check the level of the subflooring.

You will have to make sure your joists can handle the addition of considerably more weight from the plywood subfloor and any floor coverings. A plywood subfloor will bridge any minor waves in the existing floor and leveling compound would help too. Sistering joists is a job for the pros. A structural engineer may suggest sistering the joists a process whereby new joists are attached to the existing joists to add strength to the floor.

Screw the strips into the floor joists or subfloor. A day until they re level. This will give you an idea of how much work you ve got cut out for you and where. Tack a beam under the sagging joists.

On the top side of the floor another fix it idea to lay down new hardwood over the existing floor. Then set new joists same height as existing ones alongside the old. Second floor joists are nailed to the bearing walls and supported by a piece of stock called a ribbon board in this case 1 6 stock let into the studs see drawing right. Rather than attempt to lift the floor by packing out between the boards and the joist the packing invariably works loose as the floor moves with use it is easier and more cost effective in the long run to remove the floor boards and level the joists by fixing new straight ones to the existing.

If you re installing a new floor skip to checking the level and making a note of where the foundation should be worn down or built up. To do this simply cut several leveling strips the same size as the original strip. A plywood subfloor acts as a bridge for minor waves in the existing floor as well as a leveling compound. If the floor slants irregularly cut strips that bridge the cap at each floor joist.

Set down a 6 ft 1 8 m level every few feet from one end of the room to the other.