Fit a carbon monoxide alarm to a timber stud wall

Fit a battery carbon monoxide alarm to a timber stud wall, choosing a safe spot and fixing it securely into the stud.

CO-01Choose the right spot on the wallFit the alarm about 1-3m from any fuel-burning appliance such as a boiler, gas fire or wood burner, never directly above it. Mount it at roughly head height (1-1.5m from the floor) and away from corners, windows and doors, where air doesn't circulate well. Check your alarm's instructions for its exact recommended distance, since this varies by model.

RULES

1 each · Battery carbon monoxide alarm (10-year sealed unit)

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KNOW THE RULES

Under the Smoke and Carbon Monoxide Alarm (England) Regulations, landlords must fit a CO alarm in any room with a fixed combustion appliance (other than a gas cooker). It's not a legal requirement for owner-occupied homes, but it's still strongly recommended.

CO-02Confirm you're fixing into a timber studRun a stud detector or magnet along the wall to find the line of screw heads under the plasterboard - these mark the stud, usually spaced 400-600mm apart. Tap the wall: solid means stud, hollow means gap. Drill a small 2-3mm pilot hole at your chosen spot - fine pale dust means timber; grey metallic swarf means it's actually a metal stud, and you'll need a different fixing (a self-drilling metal-stud screw), not the wood screws below.

1 each · Stud detector or magnetic stud finder

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CO-03Check for cables and pipes before you drillCables and pipes can run almost anywhere in a wall, not just in the 'safe zones'. Use a cable and pipe detector, but still assume something could be there even if it shows nothing - detectors miss deep cables, armoured cable, and anything behind metal-backed board. Find your stopcock (usually under the kitchen sink) and check it turns freely before you start, so you can shut off water fast if you hit a pipe. If you have any doubt about what's behind the wall, isolate the relevant circuit at the consumer unit first.

CO-04Mark and drill the pilot holesHold the alarm's backplate against the stud in your chosen spot and mark the screw positions through the fixing holes with a pencil. Drill 2mm pilot holes about 20mm deep into the centre of the stud - this stops the screws splitting the timber and makes them easier to drive straight.

1 each · 2mm drill bit

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CO-05Fix the backplate to the studDrive a 25-30mm wood screw through each pilot hole into the centre of the stud, using a screwdriver or drill on a low, controlled speed. Don't overtighten - stop once the plate sits flush against the wall, since forcing it can crack the plasterboard around the screw.

2 each · 25-30mm wood screws

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CO-06Fit the alarm and run the testTwist or click the alarm body onto the backplate, following the manufacturer's fitting method. Press the test button and listen for the alarm sound and check the status light, following the instructions in the box - most sealed 10-year units test with a single button press and don't need a separate battery check.

CO-07Tidy upVacuum any drilling dust from the floor and skirting, and wipe the wall down. Keep the alarm's instructions somewhere safe, as they usually list a test schedule and a replace-by date printed on the unit itself.

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