Fix a loose shelf bracket on a lath and plaster wall

Refit a wobbly shelf bracket safely, finding a solid fixing point behind old lath and plaster before you drill.

SB-01Clear the area and get your tools togetherTake everything off the shelf and move furniture out of the way. Lay a dust sheet under the wall — lath and plaster drilling makes a lot of fine white dust and old plaster grit. Get your tools together before you start so you're not hunting for things halfway through.

1 each · Dust sheet

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1 each · Cordless drill/driver

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1 each · Cable and stud detector

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1 each · Bradawl

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1 each · Spirit level

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SB-02Take the bracket off and check the damageUnscrew the bracket fully and pull out the old screws or wall plugs. Push a finger gently around the hole — if it feels soft, crumbly or the plaster keys (the bits of plaster squeezed between the laths) have snapped off, the old fixing was probably never gripping anything solid. This is the usual reason a shelf bracket comes loose on a lath and plaster wall.

SB-03Work out what's behind the plasterLath and plaster walls are thin timber strips nailed to timber studs or joists, then covered in plaster — there's no metal stud version of this, so you're always looking for timber. Run your detector across the wall and listen for a change in sound, then tap gently: a dull thud usually means a solid timber stud behind, a hollow knock means you're between studs over laths only. A line of old nail or screw heads at roughly 400mm to 450mm spacing usually marks the studs.

SB-04Check for cables and pipes, and know how to shut things offCables and pipes can run almost anywhere behind a wall, not just in the 'safe zones'. Use your detector, but still treat the wall as if something could be there — detectors miss cables that are deep, in conduit, or outside the usual routes. Before you drill, find your stopcock (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, isolate the relevant circuit at the consumer unit before drilling, and turn the water off at the stopcock before cutting into anything that could carry water.

SB-05Drill a test pilot holeMark your fixing point in pencil and drill a small pilot hole, about 3mm, straight through the plaster. Watch what comes out: pale timber dust means you've hit a lath or stud, fine white plaster dust with no resistance means you're in a gap between laths, and hard grey dust means solid brick or block behind (some older lath and plaster walls are on solid masonry rather than a stud frame). This tells you which fixing to use next.

1 each · 3mm drill bit

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SB-06Fit the right fixing for what you foundIf the pilot hole hit solid timber, drill a proper pilot hole sized for your screw and drive in a wood screw straight into the centre of the stud — this is by far the strongest option, so move the bracket slightly if you need to line up with a stud. If you're only in laths with no stud behind, use a long fixing rated for lath and plaster, such as a spiral plasterboard-type anchor or a spring toggle, which spreads the load across the plaster keys rather than relying on one crumbly point. If you hit solid brick or block behind the laths, drill to the depth needed and fit a wall plug and screw sized for that masonry.

4 each · Wood screws, 50mm

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4 each · Lath and plaster spiral anchors

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4 each · Wall plugs, red

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SB-07Refit the bracket and test itScrew the bracket back on, check it's level, and hang the shelf. Push down firmly on the shelf and check nothing flexes or creaks. If the bracket carries any real weight, add a second fixing into another stud rather than relying on one point in lath and plaster.

SB-08Patch the old holes and tidy upFill any old, unused fixing holes with a flexible decorator's filler, pushing it in well so it keys into the gap. Leave it to dry, sand it smooth, and touch up with paint if needed. Vacuum up the plaster dust and fold away your dust sheet.

1 each · Decorator's filler, tube

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1 sheet · Fine sandpaper, 120 grit

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1 small tin · Touch-up paint

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