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.

How to jack up floor joists.

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. 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. 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.

Adjust the screw jack up or down to achieve a level surface. Set a hydraulic jack and post under the beam and jack up the joists about 1 8 in. Stretch a string across the floor to evaluate the amount of deflection then use it as a benchmark for improvement when jacking. 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.

Drive 16 penny nails through the holes in the plates and into the wood framing. 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. Lower the hydraulic jack to transfer the floor load to the new screw jack. The sagging floor was the symptom and somewhere under the house there had to be a cause.

The only tools required is a bottle jack string straight claw hammer circular saw and a light source. Where these repairs are not sufficient also consider shoring up joists or beams that were cut drilled or notched for pipes wires or ducts. 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.

Make repairs to settling piers and weak joists to fix swagging floors and roof lines.