Crack repair on ceilings often fails when the drywall around the crack is sagging or poorly fastened. A noticeable accumulation of applied joint compound with a crack near the center is a reliable indication of one or more failed ceiling crack repairs. If an inadequate number or drywall screws or drywall nails were used to fasten the ceiling drywall during installation, cracking and sagging may result. Age, and the expansion and contraction of surfaces caused by seasonal temperature variation, can also cause drywall surfaces to crack and sag. Ceiling crack repairs are more likely to succeed when the drywall around the crack is supported with additional drywall nails or drywall screws before crack repair begins. Refastening sagging ceiling drywall helps to keep drywall from cracking due to stress on poorly-fastened areas.
Eye protection, either safety glasses or safety goggles, should always be worn whenever preparing surfaces for paint. Respiratory system protection should be worn whenever you are creating dust or working in a dusty environment. Respiratory system protection should also be worn whenever you are applying solvent-based materials. Eye and respiratory system protection products can be purchased wherever workplace safety equipment is sold
Begin by locating ceiling joists in the cracking or sagging area with an electronic or magnetic stud finder. Use a pencil to mark their location.
Marking fastening locations along joists
Where drywall has cracked, make a mark an inch on either side of the crack. Then make marks at six-inch intervals until you have marks on either side of the crack at 1”, 7” and 13”. If drywall is still sagging past the 13” marks, then continue to make marks every twelve inches until all the sagging drywall has been marked. As a preventative measure for cracks extending less than half-way across the ceiling, refasten drywall one ceiling joist past the crack on each end of the crack. This extra support may help to prevent the crack from lengthening. As a preventative measure for cracks already half-way or more across the ceiling, refasten drywall on each ceiling joist along the crack, and in the direction of the crack, across the entire ceiling. Supporting the drywall across the ceiling in the direction of the crack will help to prevent the crack from spreading across the entire ceiling.
Where the drywall is sagging without cracking
Make a mark every twelve inches along the ceiling joists until you have reached the end of the sagging area or areas. As a preventative measure, make your last twelve-inch mark in an area that is not sagging. It is also a good idea to mark and refasten drywall one ceiling joist to the left and right of sagging areas. The extra support will help to keep the drywall from sagging around the perimeter of the repair.
Use a drill driver with magnetic drive guide to fasten drywall with 1 3/8” drywall screws at your pencil marks. Drive screws just below the surface of the drywall. If the drywall screws are difficult to drive just below the surface, then use 1¼” drywall screws. If you are using ringed drywall nails, drive them with a hammer or drywall hammer just below the surface creating a dimple.
Filling area over driven screws or nails
Use a 6” taping knife to apply joint compound to fill the area over the driven screws or nails. Fill flush to the surface. Use your taping knife to apply joint compound to conceal any build-up of joint compound from previous repairs. Allow drying. Apply a second coat of joint compound. Allow drying. Apply a third coat of joint compound if necessary. Allow drying. Sand the dried joint compound with the fine-grit side of a sanding sponge. Remove sanding dust with a wiping cloth or towel. Prime and paint.
More detailed coverage of this topic can be found in the book:
The Homeowner's Guide to Surface Preparation for Interior House Painting, on pages 134-139.
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