Do It Yourself: Magnetic stud finder key to hanging shelves

Q. I want to install some shelves on my living room walls that will hold heavy objects, including books. I want to fasten the shelf brackets directly to studs for extra strength. The walls are covered with painted drywall. How do I find the studs inside the walls?

A. Locating studs behind drywall isn’t usually too difficult, although it can be tricky when walls are covered with a thick coat of plaster or ceramic tiles.

The best bet is to buy a magnetic stud finder, a tool that contains a small magnet. When passed over a wall, the magnet reacts to screws or nails used to fasten drywall to the studs, usually moving a needle indicator.

Magnetic stud finders are sold at many home centers and hardware stores and can be bought on the Internet, usually for less than $20.

Once you have located one wall stud, you can generally find others by measuring 16 inches laterally from the first stud. In most walls, studs are installed on 16-inch centers, although in a few walls they are spaced on 24-inch centers. If in doubt, use the stud finder to check.

In some cases, studs can be located with a couple of low-tech methods. One is to darken the room, then shine a light close to and parallel to the surface; studs will sometimes stand out as slight ridges in the flat surface. Another method is to thump the wall with the knuckles; a hollow sound means you are between studs, a solid sound indicates a stud is underneath.

Contractors and others who need to locate studs frequently often invest in electronic stud finders, which are more sensitive than magnets and can find studs through thick wall coverings. Some electronic finders can also detect pipes and wiring.

It is important not to drill holes randomly in walls to attach anything, because many walls contain electrical wiring and plumbing pipes that might be damaged. Special care is needed near outlet or switch boxes or near plumbing fixtures.

Q. I have a large chest of drawers and the two top drawers refuse to open when I pull on the handles. I am afraid of breaking something if I pull too hard. How can I fix this?

A. Drawers generally stick for one of three reasons: Moisture has caused the wood to expand; the drawers are too full and the contents are blocking opening; or a drawer part has come loose and is preventing opening.

It is always helpful if a drawer above a stuck one can be removed, since it allows the stuck drawer to be emptied and examined. But since these are top drawers you can’t do that. If you think the drawers are not overfilled, I would suspect expansion by moisture.

Remove and empty a drawer below the stuck drawers. If you have a heating pad like those used for sore muscles, set it on low and put it on a dinner plate in the empty drawer. Partially close the drawer with the pad and keep an eye on it for an hour or so, then try the drawer above it. The gentle heat should help dry out the moisture and cause the wood to shrink slightly.

If this doesn’t work, check the back of the chest to see if the back panel can be removed without damaging the piece. With the back panel off, you can check for loose side panels that might be jamming the drawers.

You can also try pushing out the stuck drawers, which is less likely to break something than hard pulling. Push at the sides of the drawer, not the middle. I have used a rubber mallet to bump the sides of a very balky drawer to move it.

Once the drawer is out, examine it and the tracks it slides on for damage. Loose parts must be re-glued or otherwise repaired.

Let damp drawers dry out thoroughly before re-using. Sanding the sides of a drawer lightly or lubricating with a thin coat of wax will often improve sliding.