How To Jack Up Floor Joists

The sagging floor was the symptom and somewhere under the house there had to be a cause.

How to jack up floor joists. If a crack or sag is isolated to one area the sister joist should extend at least 3 ft. Adjust the screw jack so that the top and bottom plates are flush to the wood surfaces above and below. The only tools required is a bottle jack string straight claw hammer circular saw and a light source. Jacking up a floor and leveling it is easy with these simple instructions.

On both sides of the problem area. Adjust the screw jack up or down to achieve a level surface. Drive 16 penny nails through the holes in the plates and into the wood framing. Make repairs to settling piers and weak joists to fix swagging floors and roof lines.

A day until they re level. Jacking them up too fast may cause cracks in the walls and floors overhead. Set a hydraulic jack and post under the beam and jack up the joists about 1 8 in. 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.

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. Where these repairs are not sufficient also consider shoring up joists or beams that were cut drilled or notched for pipes wires or ducts. Tiger brand adjustable floor jack model js 15 15 gauge floor jacks telescoping jack for temporary support size range 1 1 3 4 4 out of 5 stars 368 19 67 19. Stretch a string across the floor to evaluate the amount of deflection then use it as a benchmark for improvement when jacking.

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.