Homework: Finding studs

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Electronic stud finders are great tools in certain situations, but sometimes they can be really frustrating. They can occasionally give all sorts of false positive signals, indicating where a ceiling joist is behind drywall. The device might be finding them, but the studs could be recessed from the surface of the backside of the drywall by 3/4 of an inch.

Here's an old-fashioned method of finding studs using a hammer and a nail:

1. Outlets a clue

The first thing to do when finding a stud is to look for clues as to where they would be. If the house is middle-aged or newer, say built after 1950, look for electrical wall outlets. In almost all situations, the boxes that house the outlets are nailed to the side of a wall stud. In rare instances, a particular wall outlet may have been added at a later date. In these situations, a special remodeling box is used that doesn't need to be nailed to a wall stud.

2. Baseboard holes

Also look for poorly patched nail holes in baseboard. This is less accurate because in some places, carpenters install a double bottom wall plate. This allows them to randomly nail baseboard trim into the bottom plates instead of a vertical wall stud.

3. Wall registers

You can also look on a wall for a return air duct if the house has central air conditioning or forced-air heat. Wall registers are commonly put between two wall studs. Remove a return-air grill covering, and you'll almost always see two wall studs.

4. Getting off center

The general spacing for wall studs is 16 inches on center, but they can be 24 inches. However, just because you find one wall stud's center location, that doesn't mean you can say that every other stud on the wall is 16 inches on center from that one. Rough lumber can bow and twist. It's possible for the spacing to be off by as much as 1 inch or more in either direction, especially halfway between the floor and ceiling, where studs tend to bow the most.

5. Centering

Use a 10d finish nail when finding wall studs. These create tiny holes that are easily patched with spackling compound. Find at least one part of the wall stud, and then drive nearby holes that tell where the edges of the stud are. Once you find the edges (most studs are 1.5 inches wide), you will then know where the center of it is.

6. Plaster problem

Old houses that have plaster are a little harder to work in. It requires more effort to drive the nails, and you can get fooled in houses that are old enough to have wood lath that supports the plaster. If you're working in a plastered house with horizontal wood lath strips between the studs, you need to find a void space between two pieces of lath. The wood lath strips were often 1 1/4 inches wide, and the lathers installed them with a 3/8-inch space between each one. Drive the nail up the wall until you just go through plaster and hit no wood. When you find this void, start going left and right till you locate a wall stud.

7. Sagging feeling

Houses that were built between the 1930s and the 1950s had plaster lath boards that were the early forms of drywall. Using this allowed the lathers to be far more productive instead of nailing up thousands of wood lath strips. These gypsum panels were 3/8-inch thick, 16 inches wide and 48 inches long. In certain situations, these would sag and you can see the outline of the seams on the walls and ceilings. Use the staggered 16-inch lines to help you locate the wall studs and ceiling joists. The ends of these panels almost always break on the center of a wall stud or ceiling joist.