Never use nylon wall plugs or plasterboard anchors for safety-critical fixings. Handrails, stair rails, banisters, balustrades, gates, ladders, climbing or play equipment, overhead fixings, and anything else whose failure could cause a fall or injury need a fixing designed and rated for that purpose — typically a through-bolt, a mechanical anchor or a resin-bonded anchor with a published load rating (and, for structural use, a European Technical Assessment). If you are not certain the wall and the fixing are up to the job, get advice from a builder or structural engineer.
Solid masonry walls — brick, concrete block, stone, and poured concrete — offer the best holding power of any wall type. A correctly installed fixing in solid brick can support surprisingly heavy loads, making masonry the ideal surface for TV mounts, heavy shelves, boiler brackets, and structural supports.
This guide covers everything you need to know about fixing into masonry walls: which wall plugs to use, the correct drill bits, how to drill properly, and how to handle tricky situations like crumbly mortar, engineering brick, and lightweight block.
Standard Nylon Wall Plugs for Masonry
The nylon expansion plug is a common fixing for masonry in the UK; where plugs are colour-coded, the colours are brand-specific. These expansion plugs work by gripping the inside of a drilled hole when a screw is driven into them — the plug expands outward against the masonry, creating a strong friction fit.
| Plug Colour | Diameter | Drill Bit | Screw Gauge | Typical use (indicative — not a load rating) | Best For |
|---|---|---|---|---|---|
| Yellow | 5mm | 5mm | No. 4–8 | Light | Light fixings: picture hooks, cable clips, thermostats |
| Red | 6mm | 6mm | No. 6–10 | Medium | General purpose: shelves, curtain poles, towel rails |
| Brown | 7mm | 7mm | No. 8–14 | Heavier | TV mounts, heavy shelves, radiator brackets |
| Blue | 10mm | 10mm | No. 14–18 | Heaviest of the nylon plug range | Large TV brackets and heavy wall units. Not for handrails, balustrades, gates or any fixing whose failure could cause a fall or injury — use an anchor with a published load rating instead |
Recommended Wall Plugs & Fixings
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How much weight will a wall plug actually hold?
The earlier numeric comparison has been withdrawn while we reconcile the exact fixing models, screws, substrate grades and source-table columns. Use the manufacturer’s current load sheet for the precise fixing and base material. A single-anchor recommended load is not a general fixture-weight limit and must not be multiplied by the number of fixings.
How to read it
- Identify the base material. If it is uncertain, do not select a load-table row by guesswork. Confirm the substrate before choosing the fixing and its documented load.
- Match the exact product and table. Check the fixing model, length, screw and substrate grade. Do not compare characteristic resistance, design resistance and recommended loads as if they were the same figure.
- Use the exact size and product range. Do not transfer a load value from one nominal diameter or manufacturer to another.
- Colour is not a standard. On Rawlplug’s UNO range blue is 8 mm and grey is 10 mm; other brands may use different colours, and fischer sells its SX plugs by size rather than by a colour code. Go by the printed diameter, not the colour.
- Follow the installation conditions. Use the documented drill diameter, hole depth, screw, embedment, hole-cleaning method, spacing and edge distances. Do not assume the published load applies to an oversized or damaged hole.
- Check the whole fixing arrangement. Follow the fixture and fixing manufacturers’ requirements. The number and layout of fixings, load direction and leverage matter; single-fixing values cannot simply be added.
Never use a plastic plug for a safety-critical fixing
Nylon and plastic expansion plugs are assessed under EAD 330284-00-0604, “Plastic anchors for redundant non-structural systems in concrete and masonry”. That approval assumes at least three or four fixing points sharing the load, so that if one slips the others take over, and it explicitly excludes structural and safety-critical use.
That means plastic plugs are the wrong fixing — whatever their rated load — for:
- Grab rails and handrails
- Balustrades and guarding
- Wall-hung WCs, basins and cisterns
- Gates and external ironwork
- Anything overhead, and anything whose failure could cause a fall or an injury
These need an ETA-approved metal or resin anchor, selected for the actual base material and installed in line with BS 8539:2012+A1:2021, the UK code of practice for post-installed anchors in concrete and masonry. Using an anchor in a substrate it was not assessed for can cut its performance by up to 80%, so the substrate has to be identified before the anchor is chosen. In plasterboard, no cavity fixing is adequate for a safety-critical load: the rail must be fixed to solid backing — a timber noggin or plywood pattress screwed to the studs. If you are not sure, this is the point to bring in a professional.
Get the free Drill Bit & Wall-Plug Size Chart (PDF)
Every drill size, wall-plug colour & tap size on one printable sheet.
For the full size chart with screw lengths and detailed specifications, see our Wall Plug Size Chart.
Fischer vs Rawlplug vs Unbranded — Does Brand Matter?
Wall plugs sold in the UK include Fischer, Rawlplug and own-brand or unbranded options from merchants such as Screwfix, Toolstation and B&Q. Here’s what you need to know:
- Fischer: a German maker that publishes load tables for its SX, SX Plus and DuoPower plugs in each base material, so you can check the figure for your wall. Fischer SX plug kit — check price on Amazon
- Rawlplug: Its UNO is a single plug design with published loads in solid and hollow materials, including plasterboard (Rawlplug UNO product card). Rawlplug Uno assortment — check price on Amazon
- Unbranded / own-brand: Check that the pack gives a load for your wall; if it gives none, choose a plug that does. Handrails, overhead and other safety-critical fixings need a fixing rated for that use, chosen from the maker’s datasheet.
How to Drill into Masonry — Step by Step
What You’ll Need
- Combi drill with hammer action, or SDS rotary hammer for larger holes
- Masonry drill bit (TCT tip) in the correct size
- Wall plugs and screws
- Pencil, spirit level, and tape measure
- Pipe and cable detector
- Vacuum cleaner
Step-by-Step Process
- Scan the wall: Use a pipe and cable detector to check for hidden services. Pay special attention to areas above and below sockets, switches, and radiator pipes. Bosch stud/pipe detector — check price on Amazon
- Mark the fixing positions: Use a pencil and spirit level to mark exactly where each hole needs to go. For brackets, hold the bracket in position and mark through the screw holes.
- Set the drill depth: Wrap masking tape around the drill bit to mark the required depth — the plug length plus 5–10mm extra for dust clearance.
- Drill the hole: Set your drill to hammer mode. Start slowly to establish the hole, then increase speed. Apply firm, steady pressure — let the hammer action do the work. Don’t force the bit sideways or you’ll widen the hole.
- Clear the dust: Withdraw the bit periodically to clear debris. Once drilled to depth, vacuum the hole to remove dust. This is important — packed dust reduces the plug’s expansion.
- Insert the plug: Push the wall plug into the hole. It should be a firm push fit — tap gently with a hammer if needed. The plug should sit flush with or just below the wall surface.
- Drive the screw: Insert the screw through your bracket/fitting and into the plug. Tighten until snug — don’t over-tighten. The plug should grip firmly without spinning in the hole.
Masonry Types and Their Holding Power
Not all masonry is equal. Published loads depend on the base material: Rawlplug gives 0.71 kN per 6mm UNO plug in solid brick but 0.08 kN in aerated concrete (tension). Here’s how different masonry types compare:
| Masonry Type | Drilling Notes | Fixing Notes |
|---|---|---|
| Engineering brick | Very hard — may need SDS drill. Bits dull quickly. | Use the maker’s published load for this material. |
| Solid facing brick | Standard hammer drill works well. | Use the maker’s published load for this material. |
| Dense concrete block | Standard hammer drill. Watch for aggregate. | Use the maker’s published load for this material. |
| Poured concrete | Can be very hard. SDS recommended for 10mm+. | May hit rebar — stop and reposition if so. |
| Breeze block | Easy to drill. No hammer action needed. | Reduced holding power — consider longer plugs or frame fixings. |
| Thermalite / aircrete | Very easy to drill — almost like wood. | Standard plugs may pull out. Use specialist fixings or chemical anchors. |
| Natural stone | Can be extremely hard (granite) or soft (sandstone). | Hard stone — excellent grip. Soft stone — consider resin anchors. |
Frame Fixings for Masonry
For applications where you’re fixing timber or plastic frames to masonry — such as door frames, window frames, battens, and timber cladding — frame fixings (also called hammer fixings or nylon frame anchors) are faster than plugs and screws.
A frame fixing is a long nylon plug with a pre-assembled screw. You drill through the frame and into the masonry in one operation, push the fixing through, and hammer or screw it tight. Diameters and lengths vary by maker (fischer’s SXR load table, for example, covers SXR 6 and SXR 8), so choose the size from the datasheet.
Fischer frame fixings assortment — check price on Amazon
Chemical Anchors (Resin Fixings) for Masonry
When standard expansion plugs aren’t enough — in crumbly masonry, oversized holes, or for very heavy loads — chemical anchors provide a permanent solution. A chemical anchor uses a two-part resin that bonds a threaded stud into the drilled hole. Resin anchors are the appropriate choice where the load is high or the fixing is safety-critical — work to the published figures in the anchor European Technical Assessment for your substrate rather than to a generic number.
Common uses include: satellite dish brackets, large TV mounts on questionable masonry, handrail posts, Juliet balconies, and structural steelwork connections.
Fischer chemical resin anchor kit — check price on Amazon
Common Mistakes When Fixing to Masonry
- Drilling into mortar joints: Always drill into the brick or block, never the mortar between them. Mortar has far less holding power and can crumble around the plug.
- Using the wrong drill mode: Hammer action is essential for brick and concrete. Without it, the bit just spins against the surface and overheats. Exception: thermalite and lightweight blocks — use drill mode only, as hammer action shatters them.
- Not clearing dust from the hole: Packed dust prevents the plug from sitting at full depth and reduces its expansion grip. Always vacuum or blow out the hole before inserting the plug.
- Using screws that are too short: The screw must engage the full length of the plug. Otherwise the plug does not expand fully.
- Over-tightening: This is the most common cause of a spinning plug. Once the bracket is secure and doesn’t move, stop. Over-driving the screw strips the grip out of the plug.
Watch: Video Guide
Frequently Asked Questions
Can I drill into brick without a hammer drill?
You can try, but it’s very slow and wears out bits quickly. A standard drill in rotation-only mode will struggle with most brick. For the occasional hole, a sharp masonry bit with firm pressure may work in softer brick. For anything more than a couple of holes, a hammer drill or combi drill with hammer setting is essential.
Should I drill into the brick or the mortar?
Always drill into the brick, not the mortar. Mortar joints have significantly lower compressive strength than brick and wall plugs can pull out more easily. The only exception is if you’re trying to avoid cracking a decorative or thin brick — in that case, use longer plugs in the mortar and expect significantly reduced load capacity, and never use mortar fixings for heavy or safety-critical loads.
What if the plug spins in the hole?
This means the hole is oversized or the masonry has crumbled around it. Options: (1) re-drill the hole to suit the next plug size up and use that plug with its specified screw, (2) pack the hole with a small amount of filler, let it set, then re-drill, or (3) use a chemical anchor which fills the gap with resin; work to its published loads.
Related Guides
- Wall Plug & Fixing Compatibility Guide
- Wall Plug Size Chart
- Plasterboard Fixings Guide
- Cavity Wall Fixings Guide
- What Fixings for a TV Mount?
- What Fixings for Heavy Shelves?
Recommended Masonry Fixings & Tools
Choose fixings whose maker publishes loads for your wall.
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How we compile this guide
We cross-reference compatibility details against manufacturer specifications where available, official tool manuals, and the physical standards that govern fitment (bore sizes, arbor diameters, voltage platforms, connector types). We prioritise primary sources over retailer listings, flag anything we can’t confirm, and re-verify the data on a regular cycle. Where we give a buying recommendation, we tell you the reasoning — not just the link. More on our method →
