How to Retape Wall and Ceiling Joints

Chip off loose mud from cracked seams with a putty knife. If any tape has separated from the wall, cut it off with a utility knife.

Spread mud over the cracked seam with a 4-inch drywall blade. Lay a generous trail along the seam that is approximately as wide as the blade and has no voids, or areas without mud.

Moisten a length of paper drywall tape that will cover the entire crack and lay it on top of the mud. Holding one end of the tape with your finger, scrape along the surface from the end you are holding to the opposite end, applying enough pressure to squeeze the excess mud from underneath the tape and flatten it to the wall. Transfer the excess mud back to the container for reuse.

Spread a second coat on top of the first with a 6-inch drywall blade. You don't have to wait for the first coat to dry. Use the wider blade to scrape the layer flat and feather the edges farther out into wall. Let the second coat dry until the mud is a uniform whitish-gray color, which may take anywhere from 12 to 24 hours.

Spread a third coat with a 10-inch drywall blade, feathering the edges even farther out into the wall. In most cases, three coats are all you need, but if the seam is still visible, cover it with a fourth after the previous one has dried.

Sand the newly-mudded seams lightly with 120-grit sandpaper when the last coat dries and paint wall primer onto all the exposed mud. When the primer dries, paint the seams with the wall color.