Fit a magnetic knife strip to a lath and plaster wall
Fit a magnetic knife strip safely to a lath and plaster wall by finding and fixing into the studs behind it.
AB-01Gather your tools and protect the worktopLay a dust sheet or old towel along the worktop below where you'll drill, because old lime plaster crumbles and drops lumps as you work. Get everything to hand: the knife strip, pencil, tape measure, spirit level, stud detector, drill, drill bits, screwdriver and masking tape.
AB-02Mark the position and a level lineHold the strip where you want it, usually 150-200mm above the worktop, and mark the top edge lightly with a pencil. Use your spirit level to draw a level line the full length of the strip so it doesn't slope.
AB-03Find the timber studs behind the lath and plasterLath and plaster is always nailed onto timber studs and noggins, never metal, so you're only checking where the timber is. Run your stud detector or magnet along the wall to pick up the line of lath nails, and confirm with a small pilot hole: fine timber dust means you've hit a stud, nothing or a hollow sound means you're on the lath alone, which won't hold a screw on its own. Mark the two stud centres nearest your level line so you can line the strip's fixing points up with them.
AB-04Check for cables and pipes before you drillA detector can miss cables that are deep, in conduit, or outside the usual safe zones, so treat this wall as if something could still be there even after checking. Find your stopcock now, usually under the kitchen sink, and check it turns freely so you can shut off the water fast if you hit a pipe. If you have any doubt at all, isolate the relevant circuit at the consumer unit before drilling, and don't drill near any pipe run until you know the water is off at the stopcock.
AB-05Mark and drill the pilot holesHold the strip on your level line and mark the screw positions, keeping them over the stud centres you found earlier. Stick masking tape over each mark to stop the old plaster cracking as you drill. Drill a 3mm pilot hole through the plaster, through the lath, and about 25-30mm into the timber stud behind, so the total hole depth is roughly 45-50mm.
AB-06Fix the strip into the studsUse wood screws long enough to go through the plaster and lath and at least 25-30mm into solid timber, typically 50-60mm No.8 screws. Drive them in firmly but stop as soon as they're tight, because old lath and plaster cracks if you overtighten. If the strip's fixing holes don't both land on a stud, screw one end into a stud and fix a short timber batten across the studs for the other end, then screw the strip to that. Don't rely on a plasterboard-style toggle or hollow-wall fixing in lath and plaster; it's too weak to hold and will pull out.
AB-07Check it's level and test the holdRun the spirit level along the top of the fitted strip and adjust if needed before the screws are fully tight. Give it a firm wiggle test, then load a couple of heavier knives onto it to make sure it holds securely before trusting it with the full set.
AB-08Fill any cracks and tidy upOld lime plaster often shows a hairline crack around a new fixing hole. Fill any cracks with a flexible filler, leave to dry, then lightly sand smooth. Wipe down the worktop and wall, and vacuum up the plaster dust before putting the knives back.