Things You'll Need
(1) 6-foot long 4-inch by 1-inch board
2-inch drywall screws
Framing nail gun
2-inch framing nails
Unsightly drywall bulges are usually a result of water damage or the drywall loosening from the studs. You can fix a bulge two ways: Draw the drywall back to the studs, or cut out the bulge and replace that section of drywall. Use either method to repair a bulge on a wall or ceiling. If the bulge is still wet from water damage, remove that section and replace it to avoid potential mold growth.
Secure Drywall Bulge
Find the studs on each side of the bulge, and measure the distance. Cut your 1x4-inch board to the same distance with your skill saw. Insert a screw part way into both ends of the board with your drill. Hold the board over the bulge so that each end aligns with the studs, and use your drill to finish inserting the screws into the studs. The board will draw the drywall back in without busting it as long as the bulge is not wet.
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Use your drywall screws and your drill to secure the drywall back to the studs. If the bulge is in a ceiling, you may also need to insert bracing between the studs to provide more anchoring for the drywall. Go into your attic, and locate the drywall bulge. Measure the distance between the floor joists over the bulge. Cut your 2x4-inch board into sections that will fit between the floor joists. Secure the bracing between the floor joists with your framing nail gun. Make sure that the bottom of the new brace boards do not extend past the floor joists. Insert drywall screws into the drywall to secure it to the new braces.
Insert your drywall screws so that the heads of the screws are slightly imbedded into the drywall or what is known as "counter sunk." Cover the heads of the screws with drywall compound. Use your drywall tape to cover any cracks in the bulge, and spread a thin coat of drywall compound over the tape; allow it to dry, and apply another coat. Use your sandpaper to sand the repairs smooth.
Cut Out Bulge and Replace
Draw a square around the drywall bulge using your straight edge as a guide. Measure the square to ensure that the sides of the square are the same distance, and the top and bottom of the square are the same distance. Use your drywall saw to cut out the square, and cut a new section of drywall the same size.
Cut 3-inch anchor blocks to place in each corner of the hole in the wall or ceiling. Place half of the block on the backside of the drywall, and secure it in place with a drywall screw. Allow approximately 1½ inches of the block to remain exposed to provide anchors for the new section of drywall.
Set the new section of drywall into the hole, and insert a screw into each corner and into the blocks to hold the drywall into place. Cut a strip of mesh drywall tape for each side of the square. Spread a thin layer of drywall compound over the tape, and allow it to completely dry. Apply a second coat. Allow it to dry, and sand smooth with your drywall sandpaper.