How to Repair Cracks at the Inside Corners of Walls

By Joanna Swanson

Cracks appear in walls because of small shifts in the walls or due to stress on the drywall. When they are at an inside corner, cracks can be difficult to get to, but they should be repaired in the same way that you would repair any other crack in the wall. If the crack is a small hairline crack, you will not need to use drywall tape, but if the crack is larger or there is buckling or bubbling in the drywall tape under the paint, you will need to use mesh or paper drywall tape. A contour sander can be especially helpful in smoothing repair surfaces in corners.

List of Items Needed

  • Dry cloth
  • Painters caulk
  • Paint
  • Primer
  • Utility knife
  • Drywall tape
  • Drywall compound
  • Putty knife
  • Inside corner knife
  • Sandpaper, contour sander or handheld oscillating tool with sanding accessory

    Hairline Crack

  1. Wipe the surface of the corner around the crack with a dry cloth to remove dust. Inspect the crack to make sure the drywall tape has not bubbled.

  2. Place a small amount of painters caulk over the crack and press it in with your finger. Make sure that the caulk fills the crack, but do not overfill it.

  3. Allow the caulk to dry, then sand it using sandpaper, a contour sander or a handheld oscillating tool with a sanding accessory. Apply a small amount of paint to cover the crack.

    Large Cracks

  1. Clean the surface of the corner with a dry cloth to remove dust. Prime the surface around the crack if the wall is painted with glossy paint, because drywall compound will not stick to glossy paint. Cut out bubbled or buckled drywall tape with a utility knife.

  2. Place one piece of drywall tape over the entire crack, keeping the crack in the center of the tape. You may be placing tape on both sides of the corner. If you are using paper tape, you need to put some drywall compound on the crack before you place the tape. If you must use two pieces, do not overlap the pieces or they will create a visible bump.

  3. Press the tape firmly onto the wall using a putty knife. Apply a layer of drywall compound to the tape and smooth it out using an inside corner knife or putty knife. The inside corner knife will smooth both sides of the corner at once and is easier to use, but not required.

  4. Allow the compound to dry completely and apply two more coats, allowing each to dry. Sand between coats, using sandpaper, a contour sander or a handheld oscillating tool with a sanding accessory, to smooth out the repair, feathering the edges into the surrounding wall surface.

  5. Sand the final coat of compound after it dries and prime it. Allow it to dry, then paint over the area.

© Demand Media 2011