Q: I lost precious ceramics when a wall sconce crashed to the floor. Once again, I would like to hang expensive sconces and set expensive vases on them. I am going to use museum wax to secure each vase to the sconce, but what can I use to secure the sconce to the wall so it will not crash to the floor if grandsons slam a door?

A: The trick is to get the sconce, or wall shelf, attached tight enough that it doesn’t rattle when the kids tussle or someone brushes against it as they walk by.

Sometimes a wall shelf has a bracket with screw holes accessible from the front. More often, there are two keyhole slots on the back, allowing you to fasten nails or screws to the wall, then slip the heads through the wider part of the openings and then lower the shelf into place over the narrower areas, locking the shelf into place. A heavy shelf needs at least two points of attachment to the wall; avoid getting a shelf with just one, or it might tip when jostled.

With either style of fastening, one challenge is to determine whether you can drill or nail directly to studs (the wall framing) or whether you need an anchor that grips the wall between studs. A stud finder or even a series of gentle taps against the wall with your hand can help locate the studs. Fastening directly to studs is easiest and most secure; you can just nail or screw though the wall and into the wood or metal studs. But unless the shelf is designed for fasteners that match the stud spacing (typically 16 inches apart, when measured from centerlines), you’ll need a hollow wall anchor matched to the type of wall you have and the weight of the shelf and what it will display. (With two fasteners, each one needs to carry just half the total weight.)

If your walls are drywall, then tapered, threaded anchors are the easiest to install. Their screw threads on the outside grip the drywall. Some have a slot that allows the threaded sections to separate and flare out behind the wall as you tighten the center screw, making the connection even more secure.
E-Z Ancor Drywall Anchors (50 for $12.20 at Home Depot) are the latter type; they are rated to hold up 75 pounds per anchor.

If you have lath-and-plaster walls, you can’t use screw-in anchors or any type that expand against sides of the entry hole, because that expansion could cause the plaster to crack. Molly bolts, which have wings that flare out against the back of the wall, are the easiest substitute.

For the heaviest loads on either drywall or plaster, you’ll need toggle bolts, with wings that fold in to insert through a hole, then spring open to push against the back of the drywall or plaster once you tighten a narrow bolt at the center. Traditional toggle bolts can be maddeningly difficult to install because the wings just spin freely unless there is enough tension to keep them in contact with the back of the wall. The trick is to simultaneously pull out the bolt as you tighten the threads. Also, if your shelf lacks keyhole fasteners and instead has a bracket that you can screw through, you’ll need to thread the bolt through the bracket before you install the hangers into the wall. Once the assembly is installed, you can’t remove the bolt to thread it through whatever you’re fastening because the toggle wings would come off and fall down inside the wall.

Because installing toggle bolts is a hassle, manufacturers have come out with products that work similarly but automatically apply the needed tension and allow removal and reinsertion of the bolt. WingIts World’s Strongest Fastener Standard (six for $10.49 at Home Depot) carries 300 pounds per anchor. A Toggler Toggle Bolt Drywall Anchor with quarter-inch-diameter bolts (10 for $11.98 at Lowes) holds 265 pounds in drywall and also work in plaster.

With any of these anchors, if you’re dealing with keyhole fasteners, use bolts that have pan heads, which are flat on the back. They will fit into the keyholes more securely and with less wiggle room than screws with heads that flare out in a bugle shape. The bugle shape is better, though, if you’re fastening through a bracket and want the heads to sit flush with the surface.

Once you’ve decided how to fasten to the wall, the other challenge is to place the fasteners in exactly the locations you want. Particularly with the toggle-type fasteners, you’ll need to drill relatively wide holes, so you don’t want mistakes.

Rather than marking up your wall, place a piece of painter’s tape (often blue) in the approximate location. Use tape long enough to span both attachment holes plus a little extra. With a carpenter’s level, draw a level line on the tape. Then measure between the holes in the shelf bracket or the narrow part of the keyholes and mark the locations on the tape. To avoid accidentally drilling wide holes where you could have used a nail or screw into studs, confirm the wall is hollow by drilling a test hole with the narrowest bit you have. Then drill through the tape at the marked locations.

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