How the wall anchor selector works
Choose what you are hanging, enter its weight, the number of fixing points and the type of wall, and the selector recommends the right anchor. It shows how much each anchor has to hold, and compares every anchor for your wall type, so you can see which are strong enough and which are not.
The load on each anchor is the weight of the item × a safety factor ÷ the number of fixing points. The safety factor covers bumps, vibration and weak spots in the wall: 4 for pictures, mirrors and curtain rods, 5 for shelves, and 6 for TVs and heavy cabinets.
Which anchor for which wall?
| Wall | Anchors that work |
|---|---|
| Drywall (plasterboard) | Self-drilling threaded, sleeve (molly) and toggle anchors, or a screw straight into a stud |
| Plaster and lath | Toggle bolts, or a screw straight into a stud |
| Brick or concrete | Plastic wall plugs, masonry screws, sleeve or wedge anchors |
| Hollow concrete block | Toggle bolts, or sleeve anchors into the solid web |
| Wood stud | Wood screws, structural screws or lag screws |
How much can drywall anchors hold?
The ratings below are typical working loads in 1/2 in drywall, kept on the low side for safety. The real rating depends on the brand, so always read the packet.
| Anchor | Typical load each |
|---|---|
| Plastic expansion anchor | about 15 lb (7 kg) |
| Self-drilling threaded anchor | about 40 lb (18 kg) |
| Sleeve-type (molly) anchor | about 50 lb (23 kg) |
| Toggle bolt or snap toggle | about 80 lb (36 kg) |
| Screw into a stud | about 100 lb (45 kg) |
When you must use a stud
- TVs and big mirrors. If they fall, they can hurt someone.
- Heavy cabinets and shelves. They pull outward, which is harder on an anchor than a downward load.
- Anything over about 50 lb (23 kg) on drywall.
Find the stud with a stud finder, or tap along the wall and listen for a solid sound. Studs are usually 16 in (40 cm) apart, measured from centre to centre.
Worked examples
A 20 lb mirror on drywall, two fixing points
Each anchor must hold 20 × 4 ÷ 2 = 40 lb, so a self-drilling threaded anchor is enough.
A 30 lb mirror on drywall, two fixing points
Each anchor must hold 60 lb. A self-drilling anchor is not enough, so use a toggle bolt, or screw into a stud.
A 30 lb mirror on a concrete wall
Each anchor must hold 60 lb. A masonry screw, rated at about 120 lb, is plenty.
Common mistakes
- Trusting the weight on the packet. The number is for ideal conditions in new, thick drywall.
- Ignoring what goes on the item. A shelf with books weighs much more than the empty shelf.
- Using one anchor for a heavy item. Spread the load over several fixing points.
- Using a drill bit of the wrong size. A hole that is too large means that the anchor will spin in the wall.
- Hammering plugs into brick that is soft or crumbling. Drill into the brick itself, not the mortar, for the best hold.
Tips
- Drill a pilot hole for every anchor, and use the size on the packet.
- Check for cables and pipes behind the wall before you drill. A detector can find them.
- Use masking tape on tile, and a bit made for tile or glass.
- If you are not sure, choose the stronger anchor. It costs very little more.
