Cracks in a ceiling result when the foundation of a home settles or as the home expands and contracts. While it may not be practical to fix the causes of cracking, cracks can be fixed. If you fix a crack ceiling using caulk, the job can be accomplished within a few days. Today's elastomeric caulks can expand up to 300 per cent. This means that as the crack expands and contracts, the caulk expands and contracts with it.
Dust the crack with a dust brush to remove any loose debris and dust. This will ensure the caulk adheres properly to the ceiling.
Load a tube of elastomeric caulk into a caulking gun and cut the tip off the nozzle with a utility knife.
Squirt a bead of caulk along the entire length of the crack. Allow the bead to overlap the edges of the crack by 1/16 inch.
Set the blade of a putty knife, flush on the ceiling, at one end of the crack. Scrape the putty knife along the crack. This will allow the knife to push the caulk into the crack and scrape away any excess. Wipe excess caulk off of the putty knife blade with a wet painter's rag. The caulked ceiling crack will look filled at this point. Wait 24 hour for the caulk to dry.
Inspect the caulked ceiling crack for shrinkage. If the caulk has shrunk into the crack, apply a second bead. Scrape over the second bead and let it dry for 24 hours. Repeat this process until shrinkage has stopped and the ceiling crack has been filled flush with caulk.
Wrap the tip of the tube of caulk with a piece of masking tape in between applications. This will keep the caulk from drying out. Use an A-frame ladder to reach the ceiling with ease.