How To Jack Up Floor Joists

It is critical to use heavy steel plates between the jack and the beams to avoid crushing wood fibers in the beams destroying their integrity or worse yet punching a hole through the floor.

How to jack up floor joists.

A day until they re level. Adjust the screw jack so that the top and bottom plates are flush to the wood surfaces above and below. Set a hydraulic jack and post under the beam and jack up the joists about 1 8 in. Drive 16 penny nails through the holes in the plates and into the wood framing.

On both sides of the problem area. The sagging floor was the symptom and somewhere under the house there had to be a cause. Well after doing the navy seal crawl up under the house we found that the joists that were supporting that floor were not actually attached to the sill plate any longer as seen in the photograph below. Stretch a string across the floor to evaluate the amount of deflection then use it as a benchmark for improvement when jacking.

If a crack or sag is isolated to one area the sister joist should extend at least 3 ft. Wooden shims are often used to work out squeaks and stabilize spongy areas but they can also be used for slight adjustments to specific places. Jacking them up too fast may cause cracks in the walls and floors overhead. The steel plates should be a minimum of 25 inch 0 6 cm thickness and large enough to distribute the full load of that jack across the beam.

Where these repairs are not sufficient also consider shoring up joists or beams that were cut drilled or notched for pipes wires or ducts. If the correction is minor only a 1 4 inch over an 8 foot span using shims between the floor joist and the subflooring can often rectify it without the need to raise the floor joist with a jack. The only tools required is a bottle jack string straight claw hammer circular saw and a light source. Make repairs to settling piers and weak joists to fix swagging floors and roof lines.

Jacking up a floor and leveling it is easy with these simple instructions.