JoistMap: Stud Finder

JoistMap is a stud finder app that uses your phone's magnetic sensor to detect steel fixings in a wall and estimate where the studs are. It cannot see wood. Many walls have steel screws or nails holding the board to the studs, so mark two possible fixings, measure between the marks, and it maps where the other studs should be.

SWEEP FOR THE SCREWS
Hold the phone flat on the wall and slide it slowly. A big dial with a pencil for a needle swings as the magnetometer reading jumps, and the beep quickens as the reading rises. When the reading peaks, tap to mark that fixing and put a pencil tick on the wall.

TWO MARKS BECOME A WALL MAP
Measure between your two ticks with a tape and type it in, in inches or millimetres, fractions included. Pick the stud spacing: 16 in, 24 in, 400 mm, 600 mm or your own. JoistMap draws the wall as a long ruler with your marks as red crosses and the predicted studs as pencil lines, each showing its estimated position from your first mark.

IT TELLS YOU WHEN THE NUMBERS DO NOT FIT
If your two marks do not suit the spacing, it says so instead of drawing a confident line. One may not be on a stud, or the wall may be built differently. Found another screw? Add it as a third mark and see how far it sits from its line.

TEST IT ON STEEL FIRST
The first thing the app asks is to bring the phone up to a steel screw, a pair of scissors or a fridge door, so you can watch the meter jump on metal you know is there. A case with a magnet or a metal plate throws the readings off, so take it off.

KEEP THE WALL
Save a wall with a name and a photo, tap where your two marks are on the picture, and the predicted lines are drawn across it. Come back months later when you want to hang the next shelf.

WHAT THIS APP CANNOT DO
It cannot see wood, and it is not a wire or pipe detector. It reacts to steel, then predicts from the spacing you pick, so a jump can come from any steel nearby and a prediction can be wrong. A warning sits on every result: always check for wires and pipes before you drill. Foil-backed board, metal lath and metal studs will confuse it. Plaster walls often have few fixings to find. Spacing changes near doors, windows and corners. A phone with no magnetometer cannot sweep, though the Wall Map still works from your own measurements.

STANDARD AND UNLOCKED
Sweep, the Wall Map and two saved walls are in the standard version, with a banner on the map and walls screens and none while you sweep. A single one-time unlock adds as many saved walls as you like and removes the ads. There is no subscription and no account, and your saved walls always stay open.

Questions? Write to support@clearstackapps.com