How to replace a door lock

Updated September 2026. Written and checked by the technicians at Safe & Secure Locksmith, 4105 Macdonald St, Vancouver. Every figure below matches our published price list. Call 604-734-7233 for a quote before anyone is dispatched.

Measure before you buy anything

The most common way this job goes wrong is buying a lock that does not fit the hole already in the door. Three numbers decide it, and all three take a tape measure and two minutes.

• Backset. The distance from the edge of the door to the centre of the big round hole. On North American doors it is almost always 2 3/8 inches or 2 3/4 inches. Most new locks ship with an adjustable latch that does both, but check the box.
• Bore hole. The big hole itself, normally 2 1/8 inches across. Older Vancouver houses sometimes have a smaller 1 1/2 inch bore from a lock family nobody sells any more, and a modern deadbolt will not cover it without drilling.
• Door thickness. Exterior doors are usually 1 3/4 inches, interior doors 1 3/8 inches. A lock sized for one will not clamp up properly on the other.

Write the three numbers on your phone before you leave the house. Matching the brand of what is already there is not enough on its own, because the same brand sells both backsets.

The tools you actually need

A Phillips screwdriver, a flat screwdriver, a tape measure and a pencil will do a standard swap. Add a sharp utility knife if the old hardware has been painted in, and a chisel and a drill with a spade bit only if you are moving or enlarging a strike plate. If your plan needs a hole saw in the face of the door, you are no longer doing a swap, you are doing a new installation, and it is worth reading the last section before you start.

Take the old lock off

Work from the inside face. Two screws hold the interior rose or plate to the exterior half: back them out and the two halves come apart, one to each side of the door. Then take out the two screws in the faceplate on the edge of the door and slide the latch or bolt straight out of its mortise. Keep every screw in a cup. New hardware ships with its own, but a spare of the right length has saved plenty of jobs where the frame screw hole has gone soft.

If a screw head is chewed and will not turn, stop pushing on it. A stripped screw drilled out badly turns a fifteen minute job into a door repair. Try a rubber band under the driver tip or a screw extractor first.

Fit the new one

Put the latch or deadbolt into the edge bore first, bevel facing the way the door closes, and screw the faceplate down flush. Feed the exterior half through the face bore so its tailpieces or posts pass through the latch, then bring the interior half up to meet it and start both screws by hand before tightening either.

• Test before you tighten fully. With the screws finger tight, turn the key and the thumbturn ten times. A lock that is going to bind will bind now.
• Tighten evenly, side to side. Cranking one screw fully first pulls the cylinder off centre, which is what makes a brand new lock feel gritty.
• Do not overtighten. Snug, then a quarter turn. These are machine screws into soft posts.

Get the strike plate right

Most of the complaints about a new lock are complaints about the frame. Close the door slowly and watch where the bolt lands. If it drags on the lip of the strike, or you have to lift or lean on the door to throw the bolt, the strike needs moving, not the lock replacing.

Colour the end of the bolt with a pencil, throw it against the closed strike, and the mark shows exactly which way to file or move the plate. While the plate is off, put 3 inch screws through it into the framing behind the jamb instead of the 3/4 inch screws in the box. That single change is the cheapest security upgrade in the house: it moves the resistance from the trim to the studs. If the door has dropped, the frame is out of square, or the bolt will not reach at all, that is door repair rather than lock work.

Just moved in? Rekey first

If the reason you are standing there with a screwdriver is that you just took possession, think about what problem you are solving. Replacing the lock changes the hardware. What you actually want is for every key that already exists to stop working, and you do not know how many that is: the previous owners, their adult children, a cleaner, a contractor, the realtor lockbox code, the neighbour who watered the plants.

Rekeying does exactly that. The cylinder stays in the door, the pins are changed to a new combination, a new key works and every old key stops. It is $25-$45 per cylinder for standard hardware, priced per cylinder rather than per visit, and the whole house can be keyed alike so one key opens the front, back and garage doors. See lock rekey Vancouver.

Replace instead of rekey when the lock is worn out, the finish has failed, the key already turns roughly, or it is a builder grade set you were going to upgrade anyway. A lock change is $80-$160 installed plus the hardware. Do it before the moving truck arrives if you can, because an empty house with a stale key floating around is the worst window.

When to stop and call someone

• Multipoint locks. The tall patio and European style doors with several bolts on one handle lift are not a swap, and forcing one out of alignment can jam the door shut.
• Fire rated doors. Common in condo corridors. Changing hardware can void the rating, and the strata will ask.
• Mortise locks. The rectangular box lock in older houses. The case comes out as a unit and the parts are not interchangeable between brands.
• A frame that has moved. If nothing lines up, new hardware will not fix it.
• Anything you have already drilled once. A second hole in the wrong place is how a door gets replaced.

What it costs to have it done

A lock change installed is $80-$160 plus the hardware. A rekey is $25-$45 per cylinder with the first two keys included. A standalone visit in standard hours, 8:30 am to 5 pm, carries the $75 service call, which is quoted on the phone before anyone is dispatched. Home work of every kind is on residential locksmith.

For one deadbolt on a straight door, doing it yourself is genuinely cheaper and takes half an hour. For four doors keyed alike, an old house with mortise hardware, or a door that already does not close properly, the visit costs less than the second trip to the hardware store plus the weekend.

Frequently asked questions