Stud Finder
Why Does It Matter Whether Your Studs Are Wood or Metal?
Understanding whether your walls are framed with wood or light-gauge steel is crucial. Wood studs are 2x4 or 2x6 dimensional lumber, offering solid holding power for standard wood screws. Metal studs, common in modern high-rise apartments and commercial buildings, are hollow, C-shaped steel channels. Standard wood screws will strip out of metal studs immediately. Hanging heavy items on metal studs requires specialized fasteners like self-tapping sheet metal screws or toggle bolts. This is why the material test comes before any bracket goes up, whether you are hanging a heavy mirror or mounting a television.
How Can You Tell Wood From Metal Studs With a Magnet?
You can easily determine the stud material using a magnetic scanner app. Move your phone vertically along the stud's path. If the app displays a strong, high magnetic reading (above 60 µT) continuously from the floor to the ceiling, you have metal studs. If the app detects small, sharp spikes every 8 to 16 inches vertically and falls back to a low reading (around 32 µT) in between, the studs are wood, and you are detecting individual drywall screws. That difference is the clearest single use of a phone magnetometer, and the underlying physics is set out in our explainer on magnetometer sensors. Be clear about the limit, though: a continuous band tells you the framing is steel, but because the entire channel is ferromagnetic there is no discrete peak to mark, so a magnetic app is a material test on metal-stud walls rather than a way to find the exact centre. The Stud Finder app is built and tuned for drywall over wood studs, and it does not claim otherwise.
What Do Metal Studs Sound and Feel Like?
You can also gather physical clues. Tap the wall horizontally: metal studs produce a higher-pitched, hollow, metallic ring, while wood studs produce a solid, deadened thump. If you remove an electrical switch cover, you may see the edge of the stud; steel studs are silver and thin, while wood studs are brown. When drilling a pilot hole, wood will offer continuous resistance and leave sawdust, whereas metal will resist briefly before the bit suddenly slips through into hollow air. The knock test here is the same technique used to locate a stud without any tools, just listening for material rather than position.
Which Anchors Work in Metal Studs?
For wood studs, use heavy-duty #8 or #10 wood screws driven at least 1.5 inches into the stud. For metal studs, use fine-thread self-tapping drywall screws for lightweight projects (under 10 lbs). For heavier items like TV mounts or heavy mirrors, use snap toggles (toggle bolts) inserted through the center of the steel stud, which spreads the load across the inner face of the metal channel. Whichever framing you have, keep the drilling discipline the same — the 1.25-inch rule and a taped depth stop apply to steel studs just as they do to timber, and steel studs carry cable through punched holes in the middle of the channel.