We’ve all seen those instructions that come with a new cabinet, shelf or any of a variety of other household items: “Requires solid support. Attach directly to wall studs” or words to that effect. Good advice, but how do you go about finding those often elusive studs in a wall that’s covered with drywall or plaster?
It’s a dilemma that has faced homeowners and contractors alike, and a number of high-tech and low-tech solutions have evolved over the years. Here are a few worth trying on your next project:
- Check interior moldings: Your first step, which is the most conservative and least destructive, is to look for clues that give away the location of concealed studs. You can examine horizontal moldings such as baseboards and chair rails, and look for nail holes. If the molding is stained or has a natural clear finish, fastener locations are often easy to find, even if the nail heads have been puttied over. On painted moldings, look for very slight depressions or discolorations – shining a strong light on the molding at an angle often helps. Once you’ve found one nail head, others should be spaced at regular intervals. Studs are most commonly spaced 16 inches on center (OC), meaning that the distance from the center of one stud to the center of the next one is 16 inches. Some studs, particularly in newer houses and in non-loadbearing walls, may be spaced at 24 inches OC.
One word of caution – not all moldings are nailed directly into the studs. An apron, for example – the piece of trim that’s attached underneath a windowsill – is usually attached to the rough framing that supports the window rather than into the studs. The same is true for smaller baseboards and ceiling moldings, which are nailed into the top and bottom wall plates rather than into the studs.
- Check exterior siding: Here’s another place where you can look for nail heads that indicate stud locations, at least for exterior walls. Grooved plywood siding is installed so that one or more of the grooves in each panel will fall over a stud, as well as each vertical edge of the sheet. With lap siding, the fasteners are usually installed in the top of the siding board and are covered by the board above, so they may not be obvious. However, the joints at the ends of the siding where the pieces butt into one another should fall over a stud.
Once you’ve located a stud, measure from a convenient location and transfer the measurement to inside the house. For example, you can measure from the edge of a door or window to the stud, then use that same window or door edge as a reference on the inside.
- Sounding: Most carpenters locate studs simply by tapping on the wall, which works better on a drywall-covered wall then one covered with plaster. Stud locations will have a solid feeling and a deeper tone when you tap on the wall over them, as opposed to tapping on the drywall between the studs, which has a somewhat softer feeling and a “hollow” tone.
Sounding out a stud by tapping is a matter of experience, and everyone seems to do it a little differently. Some people use a single knuckle, others use the side of their fist, still others use the rubber hand grip end of a hammer, to avoid leaving marks from tapping with the hammer’s face. However you do it, locating a stud is a combination of sound and feel, and after you’ve done a few you’ll be surprised at the accuracy of this method.
- Stud-finders: Using a mechanical or electronic stud finder is another possibility. Older, inexpensive stud finders simply use a magnet and a plastic pointer in a clear plastic case. The magnet is attracted to nails in the wall, and the pointer will swing around to indicate their location. These worked fairly well in lath and plaster walls, where long vertical lines of nails could be found in the walls holding the wood lath in place, but they’re virtually useless on drywall walls, where the nails are spaced 12 to 18 inches apart. They also are fooled by metal pipes and metal electrical conduit.
Today’s version of the stud finder is all electronic, and operates off battery power. The electronic circuitry senses changes in material density behind the wall surface, and can be used to detect wooden or metal framing, pipes, electrical wires, conduit and rebar. The more sophisticated electronic detectors have a switch or an automatic adjustment for changing between scanning functions to eliminate “false” readings, such as finding a water pipe instead of a stud. Electronic stud finders are typically quite accurate and easy to use, and have come down substantially in price in recent years.
- Probing: When you think you have a stud located, probe the wall for confirmation prior to hanging anything. Use a small finish nail and tap it through the drywall to test for the presence of the stud. Do this near the bottom of the wall just above the baseboard, or in the exact location where you intend to mount whatever item you’re installing. In that way, the hole is easily concealed with spackle, if you’ve guessed wrong about the stud’s location.
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