Drywall/ Plaster Repair In the city where I do most of my rehabilitation work, all the houses are 90 to 100 years old. Cracks and holes in the plaster are common. Often, holes in ceiling plaster are the result of water infiltrating either from the roof, or from a split plumbing line. Holes in walls are often the result of vandalism, but could be the sign of more serious foundation issues. Once the root cause is fixed I normally patch the area with inch drywall. Perform this task by placing a piece of inch drywall over the hole (lathe must be present behind the drywall). Secure the drywall to the hole with at least 2 drywall screws. Insert your roto-zip near the edge of your hole and cut the drywall by pressing the rotozip blade against the remaining plaster. Once your piece is cut, secure it with multiple drywall screws, mud the gaps, tape, re-mud then sand to a smooth finish. When dealing with floors bellow ground level if Basment Waterproofing is needed call a professional like before you Repair the walls.