How to Jack Up a Ceiling Joist

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Things You'll Need

  • Screw jack

  • Adjustable wrench

  • Level

Jacking up ceiling joists will correct sagging floors.

Jacking up a ceiling joist or beam is a process that requires the use of a screw jack. When a floor in your home begins to sag, it indicates it is receiving insufficient support due to a structural deficiency. To correct this, you can use a screw jack to lift the joist until the floor is again level. This will require first setting the screw jack in the correct position under the ceiling joist.


Step 1

Place the screw jack under the center of the ceiling joist or floor joist.

Step 2

Turn the adjustment screw counterclockwise to lower it all the way down with the adjustable wrench.

Step 3

Raise the telescoping arm as high as it will go. Align the pinholes, then insert the locking pin.

Step 4

Turn the adjustment screw to the right with the adjustable wrench. Raise the top of the screw jack until it touches the bottom of the ceiling joist.


Step 5

Place a level on the floor above the location of the screw jack.

Step 6

Turn the adjustment screw one full turn to begin raising the ceiling joist. Continue this step to raise the ceiling joist.

Step 7

View the bubble on the level to see how close you are to leveling the floor.


Place the screw jack on a solid, flat surface.