Hardware stores stock an overwhelming variety of drywall anchors. Anchors differ not only in price, appearance and installation, but more important, drywall anchors differ according to durability and load-carrying capacity. Weak anchors fail under stress, damage wall coverings, tear drywall and send heavy objects falling to the floor. Whether you're hanging shelf brackets or picture frames, an understanding the characteristics and capabilities of common drywall anchors allows you to choose a suitable anchor for your project.
Plastic Insert Anchor
The plastic insert anchor is arguably the least expensive type of drywall anchor and the easiest to install. Unlike the cylindrical plastic insert meant for solid walls, the plastic insert anchor for drywall has a roughly conical shape with a rounded tip. The interior of the plastic insert is hollow and the exterior is ribbed with serrations and scored with slits. A rim surrounds the plastic insert's base. A builder drills a hole in the drywall approximately the size of the anchor's base and pushes the insert into the hole until the anchor's rim butts against the wall's surface. As a screw threads into the anchor's hollow interior, the anchor's slits expand to grip the drywall. The plastic insert anchor typically holds lightweight loads and can be easily removed from a wall without causing damage.
The toggle bolt consists of a set of straight, metal clips hinged at a spring-loaded fulcrum. The spring forces the clips outward into a flat, parallel plane. When folded inward, the clips nest within one another and form a single clip with a slim profile. A small screw hole spanning the fulcrum accepts a machine screw included with the clip. To use a toggle bolt, a builder drills a hole in the wall to accept the folded clip. The builder attaches the screw to the clip's hole, folds the separate legs inward and presses the folded clip through the hole in the wall. As the clip passes through the hole, the separate legs of the clip spring outward. Tightening the screw causes the clip to press against and grip the interior of the wall. Toggle bolts typically carry heavy loads, but cannot be removed from a wall once inserted.
The screw-type anchor looks like a thick, hollow-bodied screw. Tapered screw threads line the exterior of the anchor's shank, and the head is flat like a wood screw's head. A large screwdriver slot, usually Phillips drive, sits at the center of the anchor's head. However, unlike a standard screw, the screw-type anchor's slot extends into the screw's shank to form a hollow shaft that accepts a smaller, wood or sheet metal screw. To use the screw-type anchor, a builder presses the sharp tip of the anchor into drywall and uses a screwdriver to twist and embed the anchor's shank into the drywall. With the anchor secured to the wall, the builder can drive a second screw into the anchor's hollow shank. Screw-type anchors are made of either plastic or metal and typically hold light to medium loads.
Metal Expansion Anchor
The metal expansion anchor consists of a hollow, metal cylinder with a threaded interior face. One end of the cylinder forms a lip that grips the wall with sharp, triangular teeth. To use the metal expansion anchor, the builder drills a hole in the drywall to accept the cylinder's shank and pushes the cylinder into the hole until the anchor's lip grips the wall's surface. As a screw threads into the cylinder, the cylinder's shank compresses, expands outward like a mushroom, presses against and grips the wall's interior face. Metal expansion anchors hold heavy loads, such as utility shelving. Like a toggle bolt, the metal expansion anchor's body typically remains within the wall cavity once the screw is removed.