Fit bay window blinds to a dot-and-dab plasterboard wall

1 each · Pencil

BW-02Find your stopcock and check for cables and pipesBefore you drill anything, find your stopcock — usually under the kitchen sink — and check it turns. Run a detector along every mark, but still assume something could be there: detectors miss deep cables, cables in metal conduit, anything behind metal-backed plasterboard, and they get confused near metal stud frames. If you have any doubt at all, isolate the circuit at the consumer unit before drilling, and be ready to shut off the water at the stopcock if you hit a pipe.

1 each · Cable and pipe detector

BW-03Work out what's behind the wall at each bracket pointRun a magnet or stud detector across each mark, listening for a change from hollow to solid, and check whether it tracks a regular line of screw heads (studwork) or nothing at all (solid masonry, or dot-and-dab over masonry). Drill a small 3mm pilot hole at one mark and look at what comes out: fine pale dust means plasterboard or plaster, coarse grey grit means masonry, timber shavings mean a wood stud, and shiny metal swarf means a metal stud track. In an older bay, expect lath and plaster — a springy, hollow feel with a slightly gritty texture, over narrow timber laths rather than a flat board.

1 each · Cordless drill

1 each · 3mm drill bit

BW-04Fix brackets where the wall is dot-and-dab plasterboardCheck the gap behind the board first — dot-and-dab usually has a 10-40mm air gap before you reach solid masonry. Drill through the plasterboard and the gap into the masonry with a 6mm masonry bit, to a total depth of at least 80mm, then fit a long dot-and-dab-rated plug (not a standard wall plug) and a screw long enough to bite at least 40mm into the solid masonry behind. A plain plug that only grips the plasterboard will pull straight out under the weight of a blind.

1 each · 6mm masonry drill bit

1 pack of 10 · Long dot-and-dab fixings (e.g. Fischer Duopower 8x80mm)

BW-05Fix brackets where the wall is solid brick or blockDrill with a 6mm masonry bit to a depth of 40-50mm. Fit a standard red or brown wall plug matched to the drill size, then drive in a 4x50mm woodscrew. Check the bracket sits tight and doesn't spin in the hole before hanging any weight on it.

1 each · 6mm masonry drill bit

1 pack of 10 · Wall plugs (6mm)

1 pack of 10 · Woodscrews 4x50mm

BW-06Fix brackets where the wall is plasterboard on timber studsLine the bracket up on the centre of the stud, not the edge, so the screw has full timber to bite into. Drill a 3mm pilot hole to stop the wood splitting, then drive in a 4x50mm woodscrew directly into the timber. No plug is needed in solid timber.

1 each · 3mm drill bit

1 pack of 10 · Woodscrews 4x50mm

BW-07Fix brackets where the wall is plasterboard on metal studsNever use a plastic wall plug or an ordinary wood screw on a metal stud — both strip straight through 0.5mm steel. For a light bracket screwing straight into the metal track, use self-drilling metal stud screws, which cut their own thread into the steel. A bay window blind bracket takes a pulling and twisting load every time it's used, so unless the bracket is very light, it's safer to use a hollow-wall toggle fixing rated for the wall thickness, fitted into the plasterboard between the studs rather than the steel itself. A full-width heavy blind, or a motorised one, needs a timber noggin fitted between the studs, or a fixing through to the masonry behind — a bracket screwed only into thin steel track is not enough on its own.

1 pack of 10 · Self-drilling metal stud screws

1 pack of 4 · Metal-stud rated toggle fixings

BW-08Fix brackets where the wall is lath and plasterLath and plaster is timber strips under lime plaster, and the plaster alone will not hold a screw — you need to find the timber lath or stud behind it. Stick a strip of masking tape over the mark before drilling to stop the old plaster cracking outward, then drill and drive a 4x50mm woodscrew into the timber you located with the detector. Go slowly and stop if the plaster starts to crumble, since it's often brittle and can break away in a wider patch than you expect.

1 roll · Masking tape

1 pack of 10 · Woodscrews 4x50mm

BW-09Check every bracket is level and secureHold a spirit level across each bracket, and across the run if you're fitting more than one blind side by side, so the headrails line up along the whole bay. Give every fixed bracket a firm pull before moving on — it should not flex, rock or pull away from the wall at all.

1 each · Spirit level

BW-10Hang the blinds and test the operationClip or slot each blind into its brackets following the maker's instructions, then run it up and down a few times to check it moves smoothly and sits square in the recess. Adjust any bracket that's pulling the headrail out of line before you finish.

BW-11Tidy up and make goodVacuum up dust and any plaster or masonry debris from the sill and floor. Fill any misplaced pilot holes with a small amount of filler, and let it dry before touching up with matching paint if needed.

1 each · Dust sheet