Fit a garage door defender lock

Fit a garage door defender to a concrete floor or masonry wall, with the right anchors and a safety check before drilling.

GDL-01Check what you're fixing into and buy the right defenderMost defenders bolt down to the concrete floor in front of an up-and-over door, with a matching hasp fitted to the door itself. Confirm your garage floor is solid concrete, not chipboard or block paving over a void, and measure your door's width before you buy. This job fixes into solid masonry — concrete floor or brick/block wall — not a stud wall or ceiling, so timber and metal stud fixings don't apply here.

1 each · Garage door defender kit (floor or wall-mounted)

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GDL-02Gather tools and PPEYou'll need an SDS drill, the right size masonry bit, safety glasses, a dust mask, gloves, and a spanner or socket set for the bolts. Clear the area in front of the door and lay a dust sheet down, since drilling concrete makes a lot of fine dust.

1 each · Safety glasses

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1 pack · Dust mask (FFP2)

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1 each · Dust sheet

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GDL-03Find the stopcock and check for cables before you drillCables can run along garage walls and floors, especially if you have a light, socket, or an automatic door opener fitted. Run a cable and pipe detector over the drilling line, but still treat the area as if something could be there — detectors miss cables in conduit or outside their range. Find your stopcock (usually under the kitchen sink) and check it turns before you start, and if there's any doubt, isolate the garage circuit at the consumer unit before drilling.

1 each · Cable and pipe detector

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GDL-04Mark up the fixing pointsHold the defender in position exactly where it will meet the door when closed, and mark through the fixing holes with a pencil or awl. Close the door and check the hasp lines up properly before you commit to drilling anything.

GDL-05Drill the masonry fixing holesFor a floor-fixed defender, drill straight down with the SDS drill using a masonry bit sized to your anchor — usually 10mm — to the depth stated on the fixing pack, typically 60-80mm. For a wall-mounted defender, drill into the brick face or a mortar joint, never right at the edge of a brick, using the same bit size and depth. Keep the drill square to the surface so the anchor sits straight.

1 each · Masonry drill bit, 10mm

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GDL-06Drill the fixing holes in the doorUp-and-over doors are usually galvanised steel — use a sharp HSS metal drill bit at a slow speed, and support the panel from behind so it doesn't flex or dent. Timber doors take an ordinary wood bit with a smaller pilot hole first. File off any sharp swarf or splinters before fitting the hasp.

1 pack · HSS metal drill bit set

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GDL-07Clean out the holesBrush or blow all dust out of the masonry holes before fitting anchors — a hole packed with dust stops the anchor gripping properly and weakens the fixing. Vacuum up any metal swarf too, since sharp filings are easy to tread on in a garage.

GDL-08Fit the anchors and bolt down the defenderUse the heavy-duty sleeve or resin anchors supplied with the kit — plain plastic wall plugs aren't rated for a security fixing that has to resist real force. Fit the anchors as instructed, then bolt the defender base down and tighten fully with a spanner or socket, checking it doesn't rock or lift.

4 each · Heavy-duty masonry sleeve anchors, M10

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GDL-09Fit the hasp and lock plate to the doorBolt or screw the matching hasp to the door rail through the holes you drilled, lining it up with the floor or wall fixing so the padlock passes through cleanly when the door is shut. Tighten every fixing fully — a loose hasp is the first thing a thief will go for.

GDL-10Test the lock before you rely on itOpen and close the door a few times with the defender disengaged to check it still swings and seats properly. Then engage the defender, fit the padlock, and check the door can't be forced open or lifted even a few millimetres while locked.

1 each · Closed-shackle padlock (if not supplied)

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GDL-11Tidy upVacuum up drilling dust and any metal swarf from the floor, and wipe down the door and defender. Give the padlock and moving parts a light spray of lubricant so they work freely, and keep a spare key somewhere safe but not near the garage itself.

1 each · Household vacuum cleaner

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1 each · Lubricant spray (e.g. WD-40)

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