The patch will be supported and fastened to two of the sides of the opening with wood support blocking. The approach I will explain supports the wallboard patch in all four corners, which is important.
- Cut two lengths of scrap wood 4" to 6" longer than the longest length of the opening.
- Make sure the wood is at least a nominal 4" in width such as a 1x4 or a 2x4.
- Place one length of wood along the longest edge inside the hole so that half the width is over the opening and the other half is over the existing wallboard.
- Position the blocking so that you have equal overlap of the wood board at each end of the opening.
- Hold the board in this position and fasten in place with 1" to 1-1/2" long drywall screws.
- Place a screw at each end and about 6" apart along the length of the opening.
- Repeat with the other side.
