Like all things, it is unlikely to create an exact science when it comes to finding studs and beams, without stripping the wall down. However, the more adept you are at using a stud finder, and the higher the quality of the sensor you decide on, will greatly affect the accuracy of your stud finding capabilities.
Common false positives depend on the type of wall sensor you are using. For example, magnetic stud finders can easily be misread, especially when the item being used is cheaper or has a weak magnet within the tool. They can also be pulled elsewhere, if there are any other magnetic materials within the walls themselves. This is becoming more common as the materials used in construction have changed greatly from when magnetic stud finders were first invented, and our reliance on metal-based products increases.
In electronic stud finders, common false positives come from inexperienced users, who mis-read the display. However, the most likely cause for these false positives come from an incorrect calibration before beginning. Without the correct calibration, the electronic stud finder can easily incorrectly identify the space and distance of the wall, joist, beam or stud. This can therefore mean that the size of the stud has been miscalculated and the project could be placed in peril.
Therefore, it’s very important before beginning your project and using your stud finder, that you locate and follow the instructions very closely. It might be a little boring at the time but it can save you heaps of work and a big headache, later down the line.