A plywood subfloor will bridge any minor waves in the existing floor and leveling compound would help too.
How to fix sagging floor trusses.
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.
Four or five beams of the same size as your floor joists typically two by eight and as long as the room.
It s best to identify problem joists and fix them before installing your underlayment and new floor covering.
Repair sagging cracked or broken floor framing.
A dip or slope in the floor could indicate one or more saggy joists beneath the subfloor.
Tack a beam under the sagging joists.
A severely arched bulged cracked or sagging floor joist can only get worse over time eventually deforming the floor above it.
Temporary adjustable floor jack tall enough to reach the floor joists from the basement floor.
Floor joists and posts support the flooring and damage to them is the most common cause of a sagging floor.
Place a screw jack found at any hardware store between the 2x8 on the floor of your attic and the sagging truss where the 2x4 is attached.
Correcting a problem joist is an easy repair and makes a big difference in your finished floor.
Temporarily screw a 3 foot 2x4 to the bottom of the sagging truss so that the 4 inch side of the 2x4 is flat against the bottom of the truss and in the center of the sag.
Replacing joists costs around 100 to 300 for each new joist.
Set a hydraulic jack and post under the beam and jack up the joists about 1 8 in.
Nailing two 2x4s together will work to span about three joists unless the sag is under a weight bearing wall.
A day until they re level.
Deteriorating floor joists or posts.
Thre ways to fix a sagging or sloping floor.
Clever fix for a sagging floor learn how to level floor framing in an old home by lifting joists with temporary walls installing a midspan beam and adding new studs to distribute the load down the the foundation.
Two four by six wood beams of 8 to 10 feet each as straight as you can find them.
You will have to make sure your joists can handle the addition of considerably more weight from the plywood subfloor and any floor coverings.
The method used to fix the problem depends on the reason the joist is sagging and the number of joists.
I suppose somewhere in the world there are floor joists that need to be repaired that have wide open clear joist bays with no pipes wires or obstructions.
I recently had to repair a floor joist that had cracked.
A dozen metal rafter ties.
Then set new joists same height as existing ones alongside the old.
