A stud finder is a handy household tool that can prevent costly mistakes when drilling into a wall -- for putting up shelves, for example. Fastening shelf supports through the wall into a solid wood stud is the most secure method. Conversely, when planning to use a molly bolt or drywall anchor, you don't want to run into a stud by accident. Electronic stud finders -- but not the less-expensive magnetic ones -- can warn you if there's live electrical wiring lurking behind the spot where you are planning to drill.
A stud finder can be a contractor's or do-it-yourselfer's best friend, but stud finders can also trigger huge frustration if they don't work well. We found many complaints from users about inaccurate results that led to holes in the wrong place. A stud finder that performs poorly can also be a safety hazard; in 2009 several Stanley stud finders were recalled because they didn't locate AC wiring accurately.
If you're positive that there's no electrical wiring in the wall -- or that you know absolutely where it is -- then reviewers favor a simple magnetic stud finder, the C.H. Hanson Stud4Sure Magnetic Stud Finder (*Est. $15). It's the favorite magnetic model in the Jan. 2011 comparison tests at Fine Homebuilding, where it proves capable of locating studs not only behind half-inch drywall, but also behind drywall plus a layer of beadboard.
Owners reviewing the Stud4Sure Magnetic Stud Finder at Amazon.com like the way it grabs onto the wall when metal is on the other side, though some of those reports are for the earlier version, which works similarly. Like other magnetic stud finders, the Stud4Sure can only locate metal -- so users are searching for the nails or screws that attach the drywall to the studs. Thus it's important to locate several apparent studs -- making sure the "finds" are plumb and centered 16 inches apart -- before drilling a hole.
Because of the need to mark several locations, another magnetic stud finder, the Binary Innovations Magic Stud Finder (*Est. $20), uses a nifty design that drops a magnet at each place so you can easily see the lineup. This stud finder earns mixed reviews from owners at Rockler.com, however, and tests at Fine Homebuilding show that its magnets are not as powerful as those in the Stud4Sure.
You can also make your own magnetic stud finder by hanging a rare-earth magnet on a chain and swinging it over the wall surface till it grabs on. This design earns some enthusiasm from users, and a video that's available at the Fine Woodworking blog demonstrates it in action. See our Useful Links section below for details.
If there's any chance of encountering live wiring in a wall or you need to locate studs behind plaster or other extra-thick wall, a magnetic stud finder just won't cut it. You need an electronic stud finder that doubles as a complete wall scanner, preferably a model that gives an audible warning of live wires. Among the models available now, the best bet is the Zircon MultiScanner i520 (*Est. $50), a full-featured stud finder/wall scanner that earns high marks for accuracy. One negative with all electronic stud finders, including the i520, is that they take a bit of time and practice to learn how to use correctly and effectively. Until that's done, reports say, you can get inaccurate results.
The Zircon i520 performs well in tests at Fine Homebuilding. It locates studs and electrical wiring in test walls made with drywall, drywall plus beadboard and plaster -- but not tile. The Zircon i520 locates the center of a standard stud (rather than just the edge, saving some steps), and alerts the user in three different ways: a bright LCD screen, an audio signal and a beam of red light. This makes it easier to work in positions where viewing the screen could be hard. Two modes are available for locating studs: standard and one for thicker walls. Two additional modes provide wiring detection and metal detection.
While reports point to the Zircon i520 as the best choice overall, some other electronic stud finders merit consideration. At Fine Homebuilding, the more expensive Bosch GMS 120 (*Est. $100) actually draws top honors in its tests thanks to its ability to locate hidden metal -- such as pipes and metal studs. It also works through tile. However, finding wiring can be trickier. Another problem is that while the GMS 120 stud finder is widely available in other countries, such as Great Britain, it is a challenge to find in the U.S.
Stanley USA is another top maker of electronic stud finders. TThe Stanley 77-730 FatMax StudSensor 400 (*Est. $40) earned a good review in 2008 tests at Popular Mechanics, but it along with the StudSensor 200 (*Est. $20) were recalled the following year for dangerous inaccuracies in locating AC wiring. Both Stanley stud finders are back on the market now, but overall, the Zircon i520 offers more convenience, features and well-tested performance.
We found the best tests of stud finders at Fine Homebuilding, whose Jan. 2011 issue compares 12 models, including two magnetic stud finders. The report at Bestcovery.com ranks the top stud finders based on the expertise and opinion of its category expert, who is also a working electrician. We found the most owner-written reviews and ratings at Amazon.com, plus a scattering at Lowes.com, HomeDepot.com, Sears.com and elsewhere.