How to Repair Joints in a Drywall Ceiling

As your house shifts and settles, cracks can appear along the joints where the drywall sheets meet. In addition, roofs constructed with manufactured trusses often expand and contract, resulting in cracks along drywall joints. Repairing the joint on a flat ceiling is a simple process you can take on yourself if you're handy around the house.

  1. Hold the straight edge just outside the damaged joint on each side and make a shallow cut into the ceiling, about 1/8" deep and as long as the damaged area. Cut as straight as possible, making a strip with the joint in the middle.
  2. Peel the old tape and dry mud out of the strip, taking care not to peel away adjacent areas of the ceiling. Your joint is now ready for taping.
  3. Cut a piece of drywall tape approximately 1" shorter than the length of your joint. The tape reinforces the new joint, but cutting it short ensures that there will be no telltale end pieces sticking out.
  4. Spread prepared drywall mud into the open seam, making sure to press it deeply into the crack using the drywall knife.
  5. Position the drywall tape on top of the wet mud, smoothing it from the center outwards, towards each end, carefully, removing any bubbles but not applying so much force that the tape slides along the mud.
  6. Smooth the tape and the drywall with large continuous arm movements, pulling the wide blade along the seam and removing excess mud. This is a very important step because any excess mud left on the ceiling creates additional sanding time later.
  7. Allow the first coat of drywall mud to dry totally before applying a very thin second and third coat of mud. The drying time for drywall mud varies by brand with some varieties, called hot mud, drying within an hour. Regular drywall mud, however, needs a few hours in a dry climate to dry entirely. It's important to allow it to dry totally before applying subsequent coats.
  8. Sand any rough spots on your dried joint and you're ready to paint your repaired portion of the ceiling.

Things You Will Need

  • Chisel
  • Straight edge
  • Utility knife
  • Drywall knife
  • Drywall tape
  • Sandpaper
  • Prepared drywall mud
  • Drop cloth


  • Concentrate on pulling the edge of your seam outwards when applying drywall mud. Because the mud will create a slight bulge in your ceiling no matter how much you try to flatten it, increasing the mud at the edges will create a longer slope, making the bulge less noticeable after painting.
  • Drywall mud shrinks as it dries, hence the need to wait until each coat is dry before applying the next.


  • Be careful when placing a ladder on top of a drop cloth. Use a folding ladder or a secure platform instead of leaning a ladder against a wall.

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