Finding Studs: Tap, Drill, Magnet or Electronic Stud Finder

Hanging a valuable picture or a flat screen TV means knowing where the studs are. On Ask This Old House, general contractor Tom Silva demonstrates several ways to find them, from a trained knuckle to store-bought finders in the $5-50 range.

Sound and feel

Silva taps on the wall and listens. The pitch moves from a low, hollow sound to something a little higher where a stud sits behind the surface. He says this works on a wall built in the late 60s or 70s and newer, which means drywall.

Plaster and lath

In a house from the mid to late 1800s the wall could be plaster and lath, where sound and feel are harder to read. His approach is to look on the baseboard, trim, crown molding or chair rail for signs of a filled nail hole. He drills a small bit close to the molding so there is no hole left in the wall. If the bit hits structure, it's a stud; if it misses, it goes right into the wall with nothing there. The reasoning is that the trim carpenter knew where the studs were and aimed for them.

Using an outlet box

Another way is to take the wall plate off an electrical outlet, after making sure the circuit is off. Electricians usually nail the box to one side of a stud before the drywall goes up, so tapping a screwdriver in right beside the box finds the stud. From there, a tape measure gives the rest: usually 16 on center in an older house, with some newer houses at 24 on center.

Stud finders

• Magnet: run it over the wall and it picks up the metal of the drywall screws. Move it up and down relatively close, because moving only across could pass between two screws.
• Wall-measuring finder: push the button, settle it in, and drag it slowly across the wall. It shows the stud and its center, which you mark.
• Multi-setting finders: some also find electrical wire or a small pipe, things you don't want to hit.
• Finder with a level: line it up, turn it on and drag it across. It shows where the stud is and its thickness, here the center of a two by four.