Owen PalmerBy Owen Palmer

Updated November 2026

To repair a sagging drywall ceiling, you find the cause, secure the loose board back to the joists, and then skim the area so it looks like the rest of the ceiling. Most sags come from fasteners that have pulled loose or from moisture weakening the board, and both are fixable without tearing out the whole panel. Plan on a few hours of work spread over a day or two, since the joint compound needs time to dry between coats.

Find Out Why the Ceiling Is Sagging

Before you touch the drywall, check the cause. A sag that is only a little bow in one spot is often a fastener problem. A sag that is soft, stained, or growing could mean water is still getting in from the roof, a plumbing line, or an upstairs bathroom, and screwing the board back up will not solve that. Look in the attic or the floor above for wet insulation, dark staining on the joists, or a drip line. If you find an active leak, stop and fix the source first. Consult a licensed plumber or roofer if you are unsure.

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Secure the Sagging Board Back to the Joists

Most sagging panels can be pulled back up with drywall screws. Use a 1-5/8-inch coarse-thread drywall screw, which holds better in wood framing than a nail.

  1. Locate the joists with a stud finder, then mark them on the ceiling with painter’s tape so you know where to drive screws.
  2. Drive a screw near the sag, going through the board and into the joist. Start at the center of the sag and work outward so the board pulls flat.
  3. Space new screws about 12 inches apart along each joist, keeping them 3/8 inch in from the edge of the board. Sink each head just below the paper surface without tearing through it.
  4. If a screw will not bite because the joist is split or the hole is stripped, move over one joist or add a short furring strip above the sag for new bite.

Once the ceiling is flat, check the surface with a straightedge. A small dimple around a screw is normal and will be covered by the patch.

Patch and Finish the Repaired Area

After the board is secure, you need to fill the screw heads and any cracks along the seams. Use the same method you would use on a standard drywall ceiling repair, and read the earlier guide on how to repair drywall cracks in ceiling if the sag has split the tape. Apply setting-type joint compound over the screw heads with a 4-inch knife, then let it dry completely. Add a second coat with a 6-inch knife, feathering the edges, and sand lightly once dry. If the sag left a crack along a seam, tape it with paper or mesh tape before coating.

Work with a light source held at a low angle across the ceiling. This shows bumps and low spots that you would otherwise miss. Keep building up thin coats rather than one thick one, since thick mud cracks as it dries.

Prime and Paint for a Seamless Match

Prime the repaired area with a drywall primer before painting. Bare joint compound soaks up paint at a different rate than the paper surface, so skipping primer leaves flashing marks. Apply two coats of ceiling paint, letting the first dry fully, and roll in one direction to limit texture differences.

Tools and Materials Checklist

  • 1-5/8-inch coarse-thread drywall screws
  • Drill or drywall screw gun with depth-set nose
  • Stud finder and painter’s tape
  • Setting-type joint compound and all-purpose joint compound
  • 4-inch and 6-inch joint knives
  • Fine sanding sponge or pole sander
  • Paper or mesh joint tape
  • Drywall primer and ceiling paint

Common Mistakes

  • Driving screws too deep and breaking the paper, which weakens the board around the hole.
  • Applying one thick coat of compound instead of several thin ones, which leads to cracking.
  • Skipping the attic check and missing a moisture source that will cause the sag to return.
  • Painting over unprimed compound, which shows up as dull patches.

A depth-set drywall screw gun makes it much easier to sink screws flush without tearing the paper, which is the most common cause of a repaired spot failing again. View on Amazon

A pole sander with a fine grit head lets you smooth the patch while standing on the floor, so you do not have to work overhead on a ladder. View on Amazon

A 6-inch stainless joint knife helps you feather compound out wider than the patch, which hides the edges better than a narrow blade. View on Amazon

FAQ

Can I fix a sagging ceiling without removing the drywall?

In many cases yes. If the board is still attached and not water-damaged, screwing it back to the joists and patching the screw heads is usually enough.

How do I know if the sag is from water damage?

Water damage often shows as brown staining, a soft or spongy feel, or sagging that grows over time. If you see any of these, check the attic and the room above before patching.

How long should I wait between coats of joint compound?

Most setting-type compounds need several hours to set, and all-purpose compound can take a full day to dry. Wait until the surface is dry and no longer cool to the touch before the next coat.

Conclusion

A sagging ceiling is usually a fixable problem once you find the cause. Secure the board to the joists, patch and finish the surface, and prime before painting. If you find water damage or the sag keeps coming back, have a professional look at the source.

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Owen Palmer

About Owen Palmer

Owen Palmer is part of our editorial team and reviews and edits our DIY home renovation guides, checking product details against manufacturer specifications and owner feedback.