How to fit cavity wall plugs: the hole this pack states
Updated: 22 October 2026
The bit in the drill is how a hollow-wall hole goes wrong. Scan for cables, use the hole this pack states, set the fixing the way that type works, and stop when the face crushes. The seven cards are on the [cavity wall plug comparison](/hub/screws-and-accessories/cavity-wall-plug). Peter F. is the DIY & tools editor. A qualifying purchase through our links can earn a commission at no extra cost to you.
The bit in the drill is how a hollow-wall hole goes wrong. Scan for cables, use the hole this pack states, set the fixing the way that type works, and stop when the face crushes.
The bit in the drill is how a hollow-wall hole goes wrong. Scan for cables, use the hole this pack states, set the fixing the way that type works, and stop when the face crushes. The seven cards are on the cavity wall plug comparison. Peter F. is the DIY & tools editor. A qualifying purchase through our links can earn a commission at no extra cost to you.
Our top picks
| Badge | Product | Drill hole | Bit in box | How it sets | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  fischer fischer DuoTec 10, 20 | 10 mm | No | Toggle drops behind the board | 8.2 | about £12.99 | View offer |
 Corefix Corefix Connect TV kit, 6 | 10 mm masonry to 100 mm | Yes | Steel core, then the screw into the block | 9.3 | about £9.49 | View offer | |
| Alternative |  Wavanta Wavanta plugs and screws, 100 | 8 mm | No | Screw draws the tube up behind the board | 5.6 | about £5.99 | View offer |
On this page
Scan, then mark
Before the bit touches the wall, look for sockets and switches. The Health and Safety Executive says look, use a detector if you can read it, and stop if you are unsure. A quiet detector can miss a low-current cable. SELECT’s note on BS 7671 puts concealed cables within 150 mm of the top or a corner, or in line with an accessory, unless protected or deep enough.
If you cannot tell hollow board from dab or solid masonry, do not drill to find out. The PlasPlugs brochure says white dust and paper means plasterboard, and grey sandy dust means lath and plaster. Dust like block may mean dot and dab. A stud under the bit may need a screw, not a plug.
Use the hole this pack states
There is no single drill size. DuoTec states 10 mm and includes no bit. Wavanta states 8 mm. PEAPIN recommends a 10 mm twist or triangle bit, not a 10 mm impact bit. DuoHM and the Corefix 24-box print no millimetre. PlasPlugs puts the size on the pack. Do not transfer the brochure’s 7 mm figure onto FCS-SCF552.
The Corefix six-pack states a 10 mm masonry hole to 100 mm, and the bit is in the box. That is a hole into the block, not a stud void. The dab bridge is on dot and dab wall fixings. Clear the dust. An oversized hole lets a DuoTec sleeve slip. Do not share Wavanta’s 8 mm bit with a 10 mm pack.
Set the fixing the way that type works
A gravity toggle has to drop behind the board. The maker page asks for at least 40 mm of cavity for DuoTec 10, and that figure is not an amazon bullet. If the void is tighter, the screw spins or misses the insert. DuoHM knots behind the panel. The listing says no extra setting tool. Stop when a PZ head starts to strip.
PlasPlugs opens wings in the void, and the screws are not in the title. Wavanta’s screw draws the tube up until it stops. Reviews put the short-screw limit at about 6 or 7 mm of bracket. If the face crushes, that hole is finished. A face plug that pulled out of gypsum is a different family, on cavity wall plug vs plasterboard plug.
Where you stop
A gas appliance is work for a Gas Safe registered engineer. Regulation 3 of the Gas Safety (Installation and Use) Regulations 1998 requires competence. A new concealed cable is an electrician’s job. If the detector reading is unclear, you stop before the hole.
Stop if the board may contain asbestos, and do not sample it yourself. Stop if the lining is part of a fire-resisting wall. The sequence is scan, confirm the wall, drill only the stated size, clear the dust, set the fixing, and stop when the face crushes. A crushed ring of plaster is the moment to fill the hole and move.
Common questions
What do you do before the drill touches the wall?
Look both sides of the wall if you can, find sockets and switches, and use a detector if you are competent to read it. The Health and Safety Executive says stop if you are unsure. BS 7671 zones include a band within 150 mm of the top or a corner. A quiet detector can miss a low-current cable. Mark the holes only after that check.
How do you tell plasterboard dust from masonry dust?
White dust with paper facing is the plasterboard clue in the PlasPlugs brochure. Grey sandy dust points at lath and plaster. Dust that looks like block or brick means the bit has reached masonry, often dot and dab rather than a stud void. The brochure is a dust clue, not the drill size on the listing. If the dust surprises you, stop and name the wall.
What hole does each pack in this set actually state?
DuoTec states 10 mm. Wavanta states 8 mm. PEAPIN recommends a 10 mm twist or triangle bit and rules out a 10 mm impact bit. The Corefix six-pack states 10 mm masonry to 100 mm, and the bit is in the box. DuoHM, PlasPlugs and the Corefix 24-box do not print a millimetre in the bullets. Do not give Wavanta a 10 mm hole because a neighbour uses one.
What if the toggle will not drop?
The cavity is too tight, the hole is obstructed, or the toggle is still inside the sleeve. DuoTec’s maker page asks for at least 40 mm of cavity. A larger hole can let the sleeve slip, so resizing is a poor repair. Move to a position with a real void. Check you are still clear of cables before that second hole.
Why does the screw spin or strip the plastic?
The screw is too short to reach the part that sets, or the driver kept turning after the fixing had seated. Wavanta and PEAPIN reviews describe short screws and stripped plastic. DuoHM reviews describe PZ heads that strip after a long wind. Once the thread is gone, that plug will not recover. Use a fresh hole.
When do you stop and get a professional?
Stop for a gas appliance and use a Gas Safe registered engineer. Stop for new concealed wiring and use an electrician. Stop if the detector is unclear, if the board may contain asbestos, or if the lining is part of a fire-resisting wall. Do not sample asbestos as part of hanging a shelf. A plug bullet that names a boiler does not move that work into DIY.
Related pages
Sources
Maker pages and UK public sources used for this comparison, checked on 20 October 2026. Shelf prices, stars and review counts are the amazon.co.uk listings checked that day.
- fischer DuoTec nylon toggle (retrieved 20 October 2026)
- fischer DuoTec recommended loads (retrieved 20 October 2026)
- fischer DuoHM cavity fixing (retrieved 20 October 2026)
- Corefix Connect 100 mm, 24 box (retrieved 20 October 2026)
- Corefix, why standard plugs fail on dot and dab (retrieved 20 October 2026)
- HSE, electricity safety (retrieved 20 October 2026)
- Gas Safety (Installation and Use) Regulations 1998, regulation 3 (retrieved 20 October 2026)
- BSI, BS EN 14566 mechanical fasteners for gypsum plasterboard (retrieved 20 October 2026)