Fixing Sagging Floor Trusses

Tack a beam under the sagging joists.

Fixing sagging floor trusses.

When inflexible flooring is installed over a substrate that dips or heaves various things. In the case of a single saggy joist which could be the result of insect damage a crack in the joist or rot the simplest way to fix the problem is to install one or two new joists on either side. Set your second four by six beam on the floor sitting on its narrow side directly under the one you ve just hung and running in the same direction. A day until they re level.

A common scenario is to install temporary jack posts and support beams then permanent posts and beams over new footings. In this style framing the entire structure will sag in that area usually causing cracks in walls ceilings or doors rubbing their frame you will need a proper footing under the post jack because your lifting much more weight if your correcting a sagging interior floor in ether style framing locate the main support beam in that area the large beam that the floor joist are sitting on raise that area keep in mind if its drastic have the foundation evaluated. Increase the pressure slowly to avoid damage to the sagging truss. Take some extra time and jack the damaged area up so that the new lumber doesn t need to be notched.

Nailing two 2x4s together will work to span about three joists unless the sag is under a weight bearing wall. Crank the jack until the truss begins to straighten. Set a hydraulic jack and post under the beam and jack up the joists about 1 8 in. Compound can correct sags and dips as deep as 1 1 2 inches.

Check sag locate the area on the floor where it sags by measuring the height in the room from the floor to. Jacking them up too fast may cause cracks in the walls and floors overhead. The process of fixing both an out of level and an out of plane floor is simply known as leveling a floor. A taut string stretched across the floor will show the amount of deflection and improvement.

If you have access to the basement or crawlspace it is possible to jack up saggy joists until they are level and then sister them so that they remain straight after the jacks are removed. In situations when sistering damaged floor joists with lumber of similar dimensions it can be easy to notch and slide the sister board into place. 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. Fixing a sagging floor requires patience and construction experience but it can be done.

Stand your floor jack between the two beams on top of the one that s on the floor and turn the thread on the jack until it wedges under the top beam.