Stud Finders and Wall Scanners
Stud Finders and Wall Scanners for Drywall, Tile and Concrete
A good stud finder shows the framing location before you insert the bit. A wall scanner can do more: it can read metal, live cable, and, in some models, even what's under a concrete slab.
This collection includes three levels of tools. Compact capacitive sensors read wood and metal framing through 1/2" and 5/8" drywall, up to 3/4" deep. Multi-mode scanners add separate wood, metal, and AC settings. At the top end, a radar wall scanner reads up to 150 mm (about 6”) into concrete for core drilling, anchor setting, and commercial renovation.
What Each Scanner Is Used for: Wood, Metal, Live Wire, Pipes
Wood studs. A stud sensor measures changes in wall density as you drag it across the wall surface. This collection includes the most basic models, which will read to 3/4", sufficient for single-layer drywall, up to 38 mm (1-1/2") for double drywall/tile on backer board.
Metal. In metal mode, the same scanner can detect steel up to 120 mm and copper up to 80 mm. This includes rebar, steel studs, and copper feed lines.
Live wire. A live wire detector senses the electrical field of energized AC wiring, typically in the area of 50 mm (2") around the wiring. It can't detect an OFF circuit.
Pipes and rebar in concrete. A radar concrete scanner can detect rebar, conduit, and water in plastic pipe in poured slabs and block walls.
How to Get an Accurate Reading
Calibration is the beginning of most bad readings. Place the tool on the wall in a blank area, turn it on, and wait for the ready signal. If no stud is available, the tool will calibrate over a raised surface. It will miss it.
Move gently at about 1" per second, while maintaining good contact with the wall. The tool must be level to obtain a correct reading.
Take a side-by-side scan. Mark the edge where the tool shows it is coming from the left, then do the same from the right. The distance from the marks to the stud center equals half the distance between the marks. On a 2x4, that should be around 1-1/2".
Check your marks against standard spacing. Residential framing in Canada is typically 16" on center, occasionally 24". If your marks don’t follow that pattern, rescan before drilling.
Foil-backed wallpaper, heavy texture, and damp drywall also throw off results. If it's lath and plaster, then use metal mode and follow nail lines.
35 Years of Helping Contractors Drill in the Right Spot
Tool Academy has carried the trades since 1989. We carry DeWalt and Bosch detection tools, from hanging cabinet kits to a slab work radar kit. Our team knows what actual jobs demand and can tell you which tools are needed for your project.
Frequently Asked Questions
Can a stud finder work through ceramic or porcelain tile?
Sometimes. The thickness of tile, thinset, and backer board can often combine to be over 3/4", which is beyond the range of most basic sensors. A scanner can read wood up to 38 mm. Another way to find the screws that hold the backer board to the studs is in metal mode.
How do I find metal studs?
There are two types of stud finder for metal studs. A capacitive sensor detects steel studs by detecting a change in density. The scanner, a metal type, picks up the steel itself and the screws along its length.
Will a stud finder detect live electrical wires?
Only models with AC detection, and only when the circuit is on. Wire inside metal conduit or armored cable may not register. Shut off the main switch when drilling around outlets or switches.
What's the difference between a stud finder and a wall scanner?
A stud finder can be used to find framing behind drywall. A wall scanner has modes for metal and live wire, and radar models can penetrate deeper into concrete and masonry.
Can a wall scanner find rebar or pipes in concrete?
Yes, with the appropriate tool. The metal-mode scanner can locate rebar to approximately 120 mm. A radar unit can measure up to 150 mm and can detect water-filled plastic pipe that a metal detector would not detect.