BATHROOMS

Fit a bathroom wall cabinet to a dot-and-dab plasterboard wall

Fit a bathroom wall cabinet securely to a dot-and-dab wall, with the right fixing for whatever is actually behind the plasterboard.

BC-01Unpack the cabinet and check what you've gotLay everything out and read the fitting instructions. Most cabinets come with basic screws and plastic plugs that are too short for a dot-and-dab wall, so plan to buy proper long fixings separately. Check the cabinet has a keyhole or bracket fitting on the back so you know how it hangs.
1 each · Bathroom wall cabinet
BC-02Find your stopcock before you drill anythingLocate your stopcock, usually under the kitchen sink, and check it turns freely. You're drilling near a bathroom wall where hidden pipework is common, so you want to be able to shut the water off fast if you hit a pipe. This takes two minutes now and saves a flood later.
BC-03Work out what's behind the plasterboardTap the wall. A dull, solid sound with almost no give means dot-and-dab plasterboard stuck to brick or block behind it. A hollow, drum-like sound that changes every 400-600mm means a stud wall instead. Run a stud detector or a strong magnet across the surface to find fixing points and screw heads, and drill one small 3mm pilot hole in an inconspicuous spot: fine grey dust means masonry, timber dust means a wooden stud, and metal swarf means a metal stud frame.
1 each · Cable and stud detector
1 each · Strong magnet
1 each · 3mm drill bit
BC-04Scan for cables and pipesRun the detector over the whole area in both directions before you drill anything bigger. Detectors miss cables that run deep, are in metal conduit, sit behind metal-backed plasterboard, or lie outside the usual safe zones above sockets and switches — so treat the scan as a warning system, not a guarantee. If there's any doubt, isolate the electrics at the consumer unit before drilling, and keep the stopcock in mind if you're working near known pipe runs.
BC-05Mark the height and positionHold the cabinet where you want it, or measure up from the basin — a common height is around 1400-1500mm from the floor to the centre of the mirror. Use a spirit level to draw a level horizontal line, then mark the fixing points through the cabinet's back plate or keyhole slots.
1 each · Spirit level
1 each · Pencil
BC-06Drill through tiles carefully, if you have themIf the fixing points land on a tile, put a strip of masking tape over the mark first so the bit doesn't skate. Use a tile bit, drill slowly with no hammer action until you're through the glaze, then switch to hammer action once you reach the plasterboard and wall behind.
1 roll · Masking tape
1 each · Tile drill bit
BC-07Choose the right fixing for your wallOn dot-and-dab, drill through the plasterboard and the 25-50mm dab gap and into the solid masonry behind, then use a long masonry plug and screw (typically 60-75mm) so the screw grips the brick or block, not just the board. On solid brick or block with no dot-and-dab layer, a standard 40-50mm wall plug and screw is enough. On a timber stud, drive a wood screw straight into the centre of the stud; if there's no stud where you need one, fit a timber noggin between the studs first rather than relying on the plasterboard alone. On a metal stud, never use a plastic wall plug or an ordinary wood screw — 0.5mm steel strips instantly. Use self-drilling metal-stud screws into the stud itself, or a toggle-type hollow-wall anchor rated for the cabinet's loaded weight if fixing between studs. On lath and plaster, locate the timber laths with your detector or a pilot hole and screw into them directly; avoid pulling fixings tight too fast, as old lime plaster can crack.
4 each · Long masonry plugs and screws (60-75mm)
4 each · Standard wall plugs and screws (40-50mm)
4 each · Wood screws (40mm)
4 each · Self-drilling metal-stud screws
4 each · Toggle-type hollow-wall anchors
1 length · Timber noggin (50x50mm)
BC-08Fit the fixings and hang the cabinetDrill the marked holes to the right depth for your chosen fixing, tap in plugs if using them, and drive the screws in leaving a few millimetres of thread showing if the cabinet hangs on a keyhole bracket. Lift the cabinet onto the screws or bracket and let it settle into place.
1 each · Drill/driver
1 each · Screwdriver
BC-09Check it's level and secureRecheck with the spirit level and adjust if needed. Give the cabinet a firm, steady pull forwards and downwards to make sure it doesn't shift — this is the only real test of a fixing, so don't skip it. If it moves at all, take it down and refit into solid masonry or a stud rather than trusting plasterboard alone.
BC-10Tidy upVacuum drilling dust from the floor and basin, and wipe down tiles. If the cabinet sits close to a shower or sink, run a thin bead of bathroom sealant along the top edge where it meets the wall to stop water tracking behind it. Dispose of any masonry or tile off-cuts in your household waste.
1 tube · Bathroom silicone sealant

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