A TV mount, a heavy mirror, grab bars, floating shelves and upper cabinets all belong on studs, not just in drywall. Here’s how to find them, and how to be sure before you drill.
How studs are spaced
In wood-framed walls, studs are usually set 16 in. or 24 in. on centre (measured from the middle of one stud to the middle of the next). The residential code’s stud table allows both, depending on the stud size and what the wall carries. A Blaine, Minnesota, framing handout based on the IRC table shows 2×4 bearing studs at 16 in. under a floor, roof and ceiling, and at 24 in. when they carry only a roof and ceiling, and non-bearing 2×4 walls at 24 in.
In practice: find one stud, then measure 16 in. along the wall. If there’s nothing there, try 24 in. Expect extra studs beside windows and doors, at corners, and wherever a wall meets another wall. Older houses and renovated walls don’t always follow the pattern.
Method 1: an electronic stud finder
- Calibrate on a blank spot. Most models calibrate when you press and hold the button against the wall. Start where you don’t expect a stud.
- Slide slowly and level. Move across the wall until it signals an edge. Mark it with a pencil.
- Come from the other side. Sweep back from the opposite direction and mark the other edge. The stud’s centre is halfway between.
- Check the next one. Measure 16 or 24 in. over and scan again to confirm the pattern.
Many stud finders also flag live AC wiring. Use it, but don’t rely on it alone. See “Avoid wires and pipes” below.
Method 2: no stud finder
- Look for fasteners. Drywall screws and nails go into studs. Shine a flashlight across the wall at a low angle and look for dimples in a vertical line, or run a strong magnet along the wall until it sticks to a screw head.
- Use outlets and switches. Electrical boxes are usually fastened to the side of a stud. Turn off the power, take off the cover plate and look, or knock either side of the box to hear which side sounds solid.
- Read the trim. Baseboard and crown are nailed into studs. Look for filled nail holes.
- Measure from a corner. Studs often start at the corner, so measuring 16 in. out from the corner is a good first guess.
- Knock. A hollow sound means a cavity, a duller sound means you’re near a stud. It only narrows the search.
Confirm before you drill
Drive a finishing nail or drill a small bit through the wall where you expect the stud, low or where the hole will be covered. If it hits solid wood after the drywall, you’ve found it. If it pushes through into nothing, move over and try again. Fill the test holes with spackle.
Avoid wires and pipes
- Wires usually run vertically above and below outlets and switches, and horizontally between them. Don’t drill directly above or below an outlet or switch.
- Plumbing runs above and below sinks and toilets and in the wall behind a tub or shower.
- Use a non-contact voltage tester near the spot, and a shallow bit or a drill stop so you go only through the drywall at first.
- If you hit something metal behind the drywall, stop. It could be a protective plate over a wire or pipe.
What if there’s no stud where you need one?
Use a hollow-wall anchor rated for the weight, or span two studs with a board or a mounting rail. Follow the weight rating on the anchor’s package, and don’t guess. For anything that holds a person’s weight, like grab bars, use the method the bar’s manufacturer specifies.
Related
- Videos that use a stud finder
- Jobs that need a stud: Install a ceiling fan, Build built-in bookshelves, Install kitchen cabinets
- The basic tool kit every homeowner needs
Sources
- City of Blaine, Minnesota, Building Department. Basic Wood Framing (stud size and spacing, from IRC Table R602.3(5)) Source