Plaster often crumbles as it ages leaving walls and ceilings unsightly. During the early 20th century, plaster was the primary wall and ceiling covering for most homes. Rather than tear out old plaster, you can hide it by covering over it.
Remove flaking plaster with a putty knife. However, do not dig into the plaster that is still attached to the wall. Wear a dust mask when removing plaster flakes. Use duck tape to secure any large, loose sections of plaster.
Use the stud finder to find the framing studs. Place the stud finder flat on the wall or ceiling surface, moving it slowly from left to right. The device alerts you when it cross over a stud. Mark each location where there is a stud at the top and bottom of a wall, and across from each other on ceilings. Snap a chalk line to connect these marks. These lines are a reference mark to follow when attaching drywall with screws.
Place the one-quarter inch drywall perpendicular to the chalk lines. For example, if you are covering a wall, then install the drywall to the wall horizontally, which would be perpendicular to the chalk lines that run up and down the wall. Do the same on a ceiling. Insert drywall screws through the drywall and into the framing studs, spacing the screws 12 inches apart going along the framing members.
Finish the drywall joints by taping the joints with drywall tape. Apply a layer of drywall mud over the tape with a 6-inch drywall knife and allow the mud to set for 24 hours. Apply a second layer of drywall mud with a 10-inch drywall knife and allow it to set for 24 hours, as well. Using a 12-inch knife, rub the blade across the dried mud to remove any ridges, and apply a third coat, feathering the edges of the mud. Allow this last coat to dry for 24 hours and sand smooth.