How to Repair Cracks in Drywall Seams in 8 Steps

Remove Damaged Drywall Tape and Mud

To start the process of how to repair cracks in drywall seams, you need to remove damaged material.

Use a utility knife to carefully cut the damaged drywall tape section out of the wall. Make the cut a few inches above and below the damaged section. Make a straight cut, which will simplify patching in the new piece of drywall tape later.

If necessary, use the knife blade to further loosen the tape so it pulls away without tearing any of the paper covering the sheet of drywall.

Use the utility knife or a putty knife to carefully scrape away any loose dried joint compound (also called drywall mud). You want to leave any solidly attached mud and tape in place if at all possible.

Fill the Drywall Seam Crack With Mud

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With the seam crack cleaned out and fully exposed, you now can fill it in with fresh joint compound. Add a very thin layer of mud across the entire section of drywall tape that you removed.

Because you’re only going to use a little bit of joint compound for this entire repair job, go ahead and purchase premixed compound, as it will only cost you a couple of extra dollars versus the hassle of mixing it yourself.

Add New Drywall Tape in the Area of the Seam Crack

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Immediately cut a piece of drywall tape that is the same length as the piece you removed. Apply it to the section where you added the thin layer of drywall mud, taking care to line up the edges perfectly so there’s no overlap.

Use your putty knife to—very gently—smooth out the tape and press it into the wet mud. Do not leave wrinkles in the tape. It needs to be perfectly flat.

Then let everything dry. How long it will take the spackle to dry will depend on the humidity level and the thickness of the layer of the mud. Typically, a couple of hours should be long enough for a thin layer. If you used quite a bit of mud because of a large crack, though, let it dry overnight to ensure it’s completely dry.

Add Another Thin Layer of Drywall Mud Over the Tape

Using your drywall taping knife, carefully spread a layer of mud over the new section of tape. Use as little force as possible to avoid tearing the new tape. Drywall taping knives typically range from 3 or 4 inches to 10 or 12 inches wide. You may want a smaller, 6-inch knife for this step and a 12-inch knife for future steps.

Feather the mud a couple of inches wider and higher than the section of tape so the mud fully covers the visible edges.

Feathering involves holding the taping knife at an angle that allows you to scrape the excess mud away in a continuous stroke while spreading mud across the edges of the tape. Scrape gently from the center of the tape outward.

You want to leave a layer of mud on the tape thick enough to cover the edges adequately. However, the thinner the layer, the easier it is to sand later, saving you time. Making the layer the perfect thickness is a challenging aspect of this job. Allow it to dry.

Repeat Adding Another Thin Layer

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Add another layer of mud in the same area. It should be extremely thin again and should go a little wider and longer than the previous layer. Allow it to dry.

Sand any Bumpy Sections

Use your fine-grit sandpaper to sand out any areas of the dried mud that are bumpy or that seem uneven. Use a damp cloth to wipe away dust after you sand.

Apply a Final Thin Coat of Drywall Mud

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Using your wide drywall taping knife, add one final coat of mud over the area. Make it extremely thin. Allow it to dry.

Sand and Paint the Repaired Area

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By this point, it should be impossible to see the seams on the drywall tape. If you can still see seams, you may need to continue repeating steps six and seven—or it may be time to call in the professionals. Feathering drywall mud and hiding tape can be a challenging process that requires a lot of patience.

If the tape is completely hidden, use the sandpaper to smooth out the area one last time. Wipe away the dust. You can now paint the wall to finish the job.