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DIY Guide 17 July 2026 · 5 min read

The Right Screw for Every Job: Wall Plugs, Rawlbolts & Fixings Explained

If you've ever stared at a wall of screws in a hardware shop and had no idea where to start, this is for you. Plain English, no waffle — here's what each type of fixing actually does and when to use it.

What’s in this guide
  • Wood screws — the everyday workhorse
  • Masonry screws — for brick and block
  • Plastic wall plugs — which colour does what
  • Plasterboard fixings — hollow wall solutions
  • Rawlbolts & heavy-duty anchors
  • Quick cheat sheet: job → fixing

Wood Screws — the Everyday Workhorse

A standard wood screw (usually a cross-head or Torx drive, with a partly smooth shank) is what you reach for when fixing into timber — shelves, door frames, skirting, batons. They come in:

Rule of thumb: the screw should go at least two-thirds of its total length into the fixing material. For a 50mm screw going through a 15mm shelf into a stud, you get 35mm of bite — plenty for most shelving jobs.

Plastic Wall Plugs — the Colour Code

Plastic wall plugs are used in masonry (brick, block, dense plaster) to grip the screw. The colour tells you the size:

Colour Drill size Screw size Typical use
Yellow 5mm No. 4–6 Light loads — mirrors, hooks
Red 6mm No. 6–8 Most common — curtain tracks, towel rails
Brown 7mm No. 8–10 Medium loads — cabinet fixings, shelves
Blue 10mm No. 10–14 Heavy loads — large shelving, brackets

Plasterboard Fixings — For Hollow Walls

Standard wall plugs don't work in hollow plasterboard walls — there's nothing for them to grip. Instead, use one of these:

For anything heavy: always try to find a stud (use a stud finder or tap the wall — solid thud = stud). Screw into the stud with a wood screw and you won't need a plasterboard fixing at all.

Rawlbolts — For Serious Heavy Loads

A rawlbolt (or expansion bolt) is what you use when you're fixing something heavy into solid masonry — a gate post, a structural bracket, a heavy shelving unit. You drill a hole, drop the bolt in, and tightening the nut expands a sleeve inside the wall that locks it in place. They come in different diameters (M6, M8, M10, M12) — the bigger, the heavier the load it can take.

Quick Cheat Sheet

The job Use this
Hanging a picture on a plaster/brick wallYellow or red wall plug + wood screw
Curtain pole on a solid wallRed wall plug + No. 8 screw
Shelf on a hollow plasterboard wallPlasterboard plug or toggle bolt
Shelf bracket into a wall studNo. 8 or 10 wood screw, no plug needed
Heavy mirror or TV bracket on masonryBrown or blue wall plug + No. 10 screw
Gate post or structural bracketM8 or M10 rawlbolt
Joining two bits of timberWood screw, no plug

We stock all of these — and we’re on Lavender Hill

Screws, wall plugs, rawlbolts, toggles, plasterboard fixings — all in stock. No delivery wait. Just come in.

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248–250 Lavender Hill, SW11 1LJ · Open 7 days

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