The locations of studs and joists hidden by walls and ceilings can be determined in any of several easy ways. Since most homes are built with these structural members spaced 16 or 24 inches apart, from center to center, simply pick a corner, measure out in increments, and then tap the surface. If you hear a hollow sound, you are between a stud or joist; if you hear a solid solid, you have hit your mark.

Another—foolproof—way is to use a stud finder. This inexpensive electronic device beeps or flashes when it passes over a stud or joist. You simply slide it along the surface until it finds a solid framing member. You can find all studs or joists using the finder—simply measure out 16 or 24 inches and then slide the device over the area.

You can also find studs or joists by looking for small dents created by the heads of the nails that attach the wallboard to the supporting members. Shining a bright flashlight at a steep angle to the wall will make them visible.

If your house has plaster walls and ceilings, you can find the studs and joists by either measuring out from a corner 16 or 24 inches and driving a small nail in an inconspicuous area, or you can use a stud finder.