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.
Place the screw jack under the centre of the ceiling joist or floor joist.
Turn the adjustment screw counterclockwise to lower it all the way down with the adjustable wrench.
Raise the telescoping arm as high as it will go. Align the pinholes, then insert the locking pin.
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.
Place a level on the floor above the location of the screw jack.
Turn the adjustment screw one full turn to begin raising the ceiling joist. Continue this step to raise the ceiling joist.
View the bubble on the level to see how close you are to levelling the floor.
Place the screw jack on a solid, flat surface.