Tack a beam under the sagging joists.
How to level floor joists in old house.
You may find this task easier if you hold the string off the sagging floor joists by attaching blocks of the same thickness at opposite sides of the basement.
We show you how to lay floor boards over the leveled joists how to cut the floor boards to the right shape and how to use a chalk line.
If the floor slants irregularly cut strips that bridge the cap at each floor joist.
Screw the strips into the floor joists or subfloor.
Set a hydraulic jack and post under the beam and jack up the joists about 1 8 in.
This job can run you 1 000 and 5 000 depending on the extent of the job.
Leveling the floor with shims is when you attach thin wedge shaped pieces of wood on top of the low areas of the joists to make the top joists even.
On the top side of the floor another fix it idea to lay down new hardwood over the existing floor.
With a taut string water or laser level make a straight line from one side of the foundation to the other.
You will have to make sure your joists can handle the addition of considerably more weight from the plywood subfloor and any floor coverings.
Thre ways to fix a sagging or sloping floor.
Determine how far the middle of the house needs to be lifted.
If the uneven floor is due to floor joists that have warped or twisted over time or were incorrectly installed the only way to level the floor is to remove the subflooring and shim the joists.
Depending upon the conditions it is possible to strengthen or repair existing framing members such as floor joists or roof rafters by adding reinforcing material sandwiching the member on either side with plywood is sometimes worthwhile but the plywood must be installed correctly for greatest strength.
If you have an uneven floor you may need to think about leveling floor joists with shims.
Nailing two 2x4s together will work to span about three joists unless the sag is under a weight bearing wall.
Use screws to secure the leveling strips to the floor every 16 inches.
Then set new joists same height as existing ones alongside the old.
A day until they re level.
A plywood subfloor will bridge any minor waves in the existing floor and leveling compound would help too.