Bolt a small safe to a dot-and-dab plasterboard wall — HomeGraft

Bolt a small safe securely to a dot-and-dab wall, checking what's really behind the plasterboard before you drill.

BS-01Check the safe and plan the positionRead the safe's manual for the fixing point spacing and the fixing type it recommends. Pick a spot low down, in a corner, away from a doorway swing, where it can't be easily levered off. Clear the floor space and move any furniture out of the way before you start.

1 each · Tape measure

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1 each · Pencil

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1 each · Spirit level

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BS-02Work out what's actually behind the plasterboardRun a stud detector or magnet along the wall to pick up screw heads or metal track. Knock along the surface: dot-and-dab sounds hollow with the occasional dull thud roughly every 300-450mm where a dab of adhesive sits. Timber studs sound hollow but solid in a straight line every 400-600mm; metal studs are similar spacing but ring slightly and pull a magnet towards fixing screws. Solid brick or block sounds solid everywhere, with no give at all.

1 each · Stud detector

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1 each · Small magnet

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BS-03Safety check before you drill anythingCables and pipes can run almost anywhere, not just in the 'safe zones', so use a detector but still assume something is there until you've proved otherwise. Detectors miss cables that are deep, in metal conduit, or behind metal-backed board, and a metal stud frame confuses cheap detectors even more. Find your stopcock now, usually under the kitchen sink, and check it turns freely so you can shut the water off fast if you hit a pipe. If you have any doubt at all, turn off the relevant circuit at the consumer unit before drilling.

1 each · Torch

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BS-04Drill test holes to map the cavity and find the dabsAt your marked fixing points, drill a 3mm pilot hole slowly. Feel with the drill bit or a bent wire for the depth of the void behind the plasterboard - a dot-and-dab cavity is usually 19-50mm deep before you hit solid masonry. Drill one or two more test holes 50mm apart to find where a dab of adhesive actually sits, and mark this on the wall in pencil.

1 each · Masonry drill bit, 3mm

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BS-05Solid brick or block behind the dot-and-dab: the strongest fixingThis is the fixing to aim for on a safe - dabs of adhesive alone will never hold this weight. Drill through your marked point, through the plasterboard and the void, and into the masonry using a 10mm masonry bit, going at least 50mm into solid brick or block beyond the void. Fit a plastic sleeve or packer over the bolt where it crosses the void so tightening doesn't crush the plasterboard, then use a masonry throughbolt long enough to reach - typically 90-120mm overall for a standard dot-and-dab wall.

1 pack · Masonry throughbolts, M8 x 100mm (pack of 4)

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1 each · Masonry drill bit, 10mm

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4 each · Plastic sleeve packers

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BS-06Plasterboard on timber studs: screw into the woodIf your test hole brought out pale wood dust and hit solid resistance about 12-15mm in, you've found a timber stud. Reposition the safe if needed so at least two fixing points land on studs, usually 400mm or 600mm apart, and drill a 3mm pilot hole into the centre of each. Use a coach screw or heavy-duty wood screw that bites at least 40mm into the timber - don't rely on the plasterboard alone for the other fixing points.

1 pack · Coach screws, 8 x 75mm (pack of 4)

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1 each · Pilot drill bit, 3mm

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BS-07Plasterboard on metal studs: why this needs a different planA pilot hole through a metal stud brings out fine, bright metal swarf, not dust. Never use a wood screw or plastic wall plug here - it strips straight through 0.5mm steel in seconds. A safe is too heavy for even the correct metal-stud toggle fixing to hold safely on its own, because it pulls hard against the wall. Fit a timber noggin between the studs, or fix long bolts through the board and studs into any masonry behind, or ask a joiner to add a plywood backing panel screwed to the studs first.

1 each · Timber noggin, 50 x 100mm x 600mm

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8 each · Self-drilling metal stud screws

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BS-08Lath and plaster: handle with careIn houses built before the 1930s, a pilot hole may show thin wooden laths behind a much thicker, crumblier plaster layer that cracks or comes away easily. Find a timber stud or joist behind the laths the same way as a timber stud wall, and use a screw that reaches through the plaster and lath into solid timber by at least 40mm. Never rely on the plaster or laths alone to carry a safe's weight.

1 pack · Coach screws, 8 x 100mm (pack of 4)

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1 tub · Plaster repair filler

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BS-09Offer up the safe and mark final positionsWith a helper, hold the safe or its backplate against the wall over your prepared fixing points. Check it's level and mark through the fixing holes onto the wall precisely, adjusting slightly if needed to keep every point on a stud or a solid dab. Lift the safe away again before final drilling if your marks have shifted.

BS-10Fit and tighten the fixingsInsert each bolt or screw and turn it in by hand first to avoid cross-threading. Tighten with a spanner or screwdriver in a criss-cross pattern so the safe pulls evenly onto the wall, stopping once it feels snug - don't overtighten. Once every fixing is tight, pull firmly on the top of the safe to check it doesn't move or pull away from the wall.

1 each · Spanner set

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BS-11Tidy upVacuum masonry, plaster and timber dust from the floor and skirting, and wipe the wall and safe down with a damp cloth. Bag up offcuts and packaging, and store any spare fixings somewhere you'll find them again.

1 each · Dust sheet

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2 each · Rubbish bags

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