How to Choose the Right Screw or Fixing for the Job

Most fixing failures come down to one of two mistakes: the wrong wall plug for the wall type, or a fixing rated for less weight than it's actually carrying. Getting this right is mostly about matching the fixing to the wall and the load, not about buying the most expensive option on the shelf.

Alongside the fixing itself, drilling the correct pilot hole matters just as much — see our guide on what size drill bit you need for a quick reference.

Work out your wall type first

This determines almost everything else about which fixing to use:

• Solid masonry (brick, block, concrete) — the most common wall type in older UK homes and load-bearing walls generally. Needs a drilled hole and a wall plug rated for masonry.
• Plasterboard on timber or metal studs — common in stud partition walls and most modern internal walls. Needs either a fixing into the timber/metal stud itself, or a specific plasterboard fixing if you can't hit a stud.
• Plasterboard on dot-and-dab (a thin plasterboard layer bonded to masonry with adhesive dabs, common in newer builds and some renovated older properties) — behaves differently again; a standard masonry plug can sit in the air gap behind the board and fail to grip anything solid.

A cable/stud detector (see our guide to essential DIY tools) will tell you which you're dealing with, and critically, whether there's a cable or pipe in the way before you drill — always check this first regardless of which wall type you think you're looking at.

Fixings for solid masonry

Standard plastic wall plugs with a wood screw cover most light-to-medium loads — shelving, curtain poles, small brackets, picture frames. For anything heavier — a TV bracket, a full bookshelf, kitchen wall units — use a rated heavy-duty plug or, for the heaviest loads, a proper masonry anchor bolt designed for structural or high-load fixing. Always check the weight rating printed on the packaging against what you're actually hanging, including a reasonable safety margin rather than fixing right up to the stated limit.

Fixing into a stud wall

Wherever possible, fix directly into the timber or metal stud rather than relying on the plasterboard alone — plasterboard on its own has very little load-bearing capacity and will pull apart under sustained weight. If you can't hit a stud, use a proper plasterboard fixing (a self-drilling plasterboard anchor for lighter loads, or a spring/gravity toggle for heavier items) rather than a standard wall plug, which will simply spin in the hollow cavity behind the board and never seat properly.

Fixing into dot-and-dab plasterboard

This wall type catches a lot of people out because it looks like a normal masonry wall from the front but has an air gap behind the plasterboard layer. A standard masonry plug drilled without accounting for this gap won't grip the solid wall behind it properly. Purpose-made dot-and-dab fixings, or fixings long enough to bridge the gap and anchor into the masonry behind, are the reliable option — if you're not sure which wall type you have, a stud detector that can identify the cavity is worth using before committing to a fixing method.

Screw types and when they matter

• Standard wood screws (Pozidriv/Phillips head) — general-purpose, fine for most fixings into timber and with a wall plug into masonry.
• Self-tapping screws — for fixing into thin metal without a pre-formed hole, cutting their own thread as they go.
• Decking/outdoor screws — always use screws rated for exterior/treated timber outdoors; standard interior screws corrode within a season or two of weather exposure.
• Plasterboard screws — a specific coarse-thread screw designed to bite into plasterboard when fixing it to a stud, not the same as a general wood screw despite looking similar.
• Machine screws and bolts — for fixing into pre-tapped metal or through material with a nut on the other side, a different category entirely from wood/self-tapping screws.

Getting the length right

As a rough rule, a screw should penetrate the base material (not counting whatever you're fixing to the wall) by at least 25-30mm for a secure hold in masonry, and enough to fully engage a stud (typically 35-40mm minimum) for stud walls — always check the specific fixing manufacturer's guidance for the load involved rather than relying on a rule of thumb for anything genuinely heavy.

A few genuinely common mistakes worth avoiding

Overtightening a screw into plasterboard, which crushes the board around the fixing and weakens its grip rather than strengthening it; using an undersized wall plug because it's what was already in the drawer rather than buying the correct size; and skipping the pilot hole in hardwood, which frequently causes the wood to split rather than accept the screw cleanly. All three are easy to avoid once you know to look out for them.

When to stop and get professional advice

For genuinely heavy fixings — wall-hung boilers, heavy floating shelving carrying real weight, anything structural — get advice specific to the fixing and wall rather than guessing based on a general guide like this one. The cost of the wrong fixing failing is rarely just the item falling; it's often damage to whatever's underneath it too, and in some cases a genuine safety risk.

Frequently asked questions