A stud finder detects changes in density or capacitance behind a wall to locate the studs.
Types
- Magnetic: detect nails and screws in studs.
- Electronic (capacitive): sense density changes behind the drywall.
- Radar-based models detect through more materials.
How to use
- Calibrate on an empty wall section.
- Slide slowly until it alerts.
- Mark both edges, then find the center.
Stud spacing
Studs are usually 16 inches apart on center, sometimes 24 inches.
Tips
Pipes and wires can cause false positives.
Magnetic stud finders
These locate the nails or screws in studs using a magnet. They are simple and require no batteries. Slide the magnet over the wall until it sticks, then find the line of fasteners going up and down.
Electronic stud finders
They sense changes in wall density by measuring the dielectric constant (capacitance). When the device passes over a stud, the density rises and the unit lights up or beeps. Higher end models detect wires, pipes and live AC wiring.
Radar based and deep scan
Some professional models use radar to see through thicker materials.
Using the device
- Calibrate it on an empty section of wall, with the unit flat against the wall.
- Slide slowly in one direction until it signals.
- Mark the first edge, then scan from the opposite direction to find the other edge.
- The center of the two marks is the stud center.
- Confirm by finding the stud again higher or lower on the wall.
Standard spacing
Studs in US homes are typically spaced 16 inches on center, and sometimes 24 inches. A stud is about 1.5 inches wide, so the center is about 0.75 inches from each edge.
Non-tool methods
Tap on the wall and listen for a solid sound instead of hollow. Look for outlets and switches, which are usually attached to a stud on one side. Use a small finish nail to test.
Caution
Walls can contain pipes and electrical wires, so use a stud finder with AC detection and avoid drilling deep near outlets and switches.
Weight limits
Hang heavy items such as TVs and shelves into studs or use proper wall anchors rated for the load.
Detection technologies
A magnetic stud finder uses a magnet to detect nails or screws in studs. An electronic stud finder senses changes in capacitance, or density, as it moves across a wall, indicating the denser stud behind the drywall. Radar based and deep scan models can detect studs behind thicker walls, and some detect metal or live AC wiring. Calibrate the tool on an empty part of the wall, then slide it slowly in one direction, and mark both edges of the stud. Studs are normally 1.5 inches wide and spaced 16 inches center to center, sometimes 24 inches in newer construction.
Safety and backup methods
Be careful when drilling near outlets or switches, because wires run vertically from them, and plumbing and wiring can be located in the wall cavity. A stud is often found next to an outlet box. Without a device, tap the wall and listen for a more solid sound, or use a small finish nail to probe. Use stud mounted hardware for heavy items such as TVs, shelves and cabinets, and use rated anchors for hollow drywall. A magnet can locate drywall screws, which run along the stud line.
Based on data from home improvement trade guides and manufacturer manuals
