Q: After installing a 2-by-2-foot drywall patch into a ceiling, I realized the piece was too thin and has a “pushed in” look, compared to the original. The difference is about 1/8 inch. How I can fill the dip in the drywall?
A: It’s common for ceilings to utilize 5/8-inch drywall while the walls are 1/2 inch, which would account for the difference in thickness that you’re experiencing in your ceiling patch. You have three options: Remove the patch and replace with 5/8-inch drywall; push out the patch from behind with furring strips; or, fill in the void with several thin coats of drywall compound. If you choose the latter, use a setting type compound for heavy fill coats. You can do a final skim coat with standard ready-mixed joint compound.