How to Level a Sagging Ceiling Joist

Slightly sagging ceilings can cause the drywall to crack and if not fixed soon can lead to greater structural issues. The likely culprit of a sagging ceiling is a weakened ceiling joist. Repair weakened ceiling joists to restore evenness to a ceiling. To repair, remove the drywall or any other ceiling sheathing in the area directly below the problematic joist. After removing the wall covering, the exposed joist sits ready for straightening and reinforcement.

Jacking stand(s)
Screw jack(s)
Adjustable wrench
Level
Construction adhesive
Matching joist
16d nails
Hammer

Instructions

- 1
  Place a jacking stand directly under the lowest sagging point of the joist. Longer joists may require two or more jacks. Locate multiple stands to distribute the weight of the sag evenly between the jacks. Place screw jacks on top of the jacking stands.
- 2
  Turn the adjustment handle on the jack with an adjustable wrench to raise the arm until it hits the bottom-center of the joist.
- 3
  Set a level against the bottom of the joist.
- 4
  Continue to turn the adjustment handle to raise the jacks until the joist becomes level. Raise multiple jacks at the same rate. Raise the joist extremely slowly. For joists with a greater than 1/8-inch sag, only raise the joist 1/8-inch each day until level.
- 5
  Apply a zigzagging bead of construction adhesive across one side of the original joist.
- 6
  Set a new, matching joist against that side of the joist. Secure the joist by driving columns of three 16d nails through the joists at intervals of 16 inches.
- 7
  Lower and remove the jacks.

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