How to Fill in Sheetrock Joints

Corner Joints

• 1

  Prepare your joint compound following the instructions on the container. For ease of use, prepare the compound then transfer a manageable amount onto a paint tray.

• 2

  Use a corner blade to press the joint compound into the seam. Start from the ceiling and work down. Fill the joint completely with a small amount of overfill.

• 3

  Cut a strip of paper corner compound tape the length of the joint. Fold the tape along the groove. Align the groove with the joint starting at the top and working down. Press the folded tape into the joint firmly.

• 4

  Use a 5-inch taping knife to press the tape to the wall on both sides of the joint. Start at the top and work down. Press the taping knife to the joint and work out on both sides. Make sure to push out any air bubbles. The tape should be smooth and flat.

• 5

  Using a corner blade, apply a thin, even layer of joint compound over the tape. The compound tape should still be visible. Spread the joint compound out 1/4 inch beyond the compound tape on either side. Allow the compound to dry according to manufacturer's recommendations. The joint compound is dry when it is white and chalky to the touch.

• 6

  Using 80-grit sandpaper, sand the surface to remove any ridges. The surface should be flat and even with the wall.

• 7

  Using a corner blade, apply a second, thin layer of joint compound that extends 2 inches beyond the original layer. Allow to dry then sand to a smooth, even finish with 120-grit sandpaper.

Wall Joints and Screw Holes

• 8

  If the sheetrock sections are touching, use a 5-inch taping knife and spread the joint compound onto the seam, extending out 1/4 inch on either side of the seam. Make sure the seam is filled with joint compound. Allow to dry. Lightly sand using 80-grit sandpaper, removing any lumps or ridges. Repeat the process, extending the compound at least 1/4 beyond the original application line. Sand the final application with 120-grit sandpaper. The finished product should be smooth and even with the wall.

• 9

  If there is a gap and the sheetrock sections are not touching, fill the gap with joint compound. Cut a strip of fiberglass sheetrock tape the length of the joint and apply. Use a 5-inch taping blade to press the tape in place and apply a thin layer of joint compound all over the tape, extending 1/4 inch beyond the edge of the tape on either side. Allow to dry. Lightly sand any joint compound ridges. The tape will still be visible. This process will need to be repeated until the tape is no longer visible. On repeat applications, extend the joint compound out at least 1/4 inch beyond previous applications.

• 10

  For screw holes, make sure the screw is below the surface of the sheetrock. Use a 2-inch taping blade to fill the hole with joint compound. Spread the compound out about 1/4 inch around the hole. Allow to dry then sand with 80-grit sandpaper. Depending on the depth of the hole, this process may need to be repeated several times to achieve a smooth, even finish.