How to fit a door lock

Make your doors more secure with this easy-to-follow guide. We take a look at two different lock mechanisms; the mortise lock and the cylinder rim lock. The mortise lock is probably the more difficult of the two to install without basic woodworking skills.

The mortise is however more versatile in that it can support more ornate and solid cast knobs and levers. If you're having trouble working out how much wood to chop out of the door to install a mortise, use a mortising jig to help you. For a simpler option, go for the cylinder rim lock.

Level of difficulty

Level 2: Intermediate

What you need

• Dust sheet
• Either a mortise lock or cylinder rim lock kit
• Utility knife
• Chisel
• Pencil
• Power drill
• Screws
• Hammer

The steps to follow

Fitting a mortise lock

1. Cover your work area with a dust sheet.
2. Decide on the height of the lock on the door and mark the height on the edge of the door.
3. Place the lock against the edge of the door and mark the top and bottom of the lock.
4. Measure the thickness of the mortise lock’s front plate and apply this measurement as the amount of wood you need to chop out to fit the lock into the door.
5. First use a power drill to make a hole then use a chisel and hammer to carve inside the hole to remove the waste wood.
6. Fit the lock in the hole to see if it's deep enough for the lock. Take out some more wood if it's not a perfect fit.
7. Place the faceplate on the edge of the door and mark around it with a utility knife.
8. Carve out enough waste wood for the faceplate to fit in against the edge of the door.
9. Place the lock body against the face of the door, and mark the keyholes with a bradawl.
10. Drill keyholes with a power drill.
11. Secure the lock in the hole you've carved out and screw the cover plate and escutcheons to the side of the door.
12. For the striking plate, place it on the doorframe and mark its position.
13. Follow the marked area to cut out a shallow recess with a chisel and hammer.
14. Fit the striking plate and secure it with screws.
15. Your mortise lock is ready for use.

Fitting a cylinder rim lock

1. With the template provided in your cylinder rim lock kit, place it on the door and mark the holes that are needed in fitting this lock.
2. Drill the holes with a power drill. Also make a hole to pass the cylinder through.
3. Next pass the cylinder into the hole and saw it to length; enough for the flat connecting bar to attach to the lock body.
4. Using the same template, mark the lock body on the door.
5. Chop away a shallow recess to allocate the mounting plate and the lock body.
6. Screw the mounting plate on the door.
7. Mount the lock body and the cylinder to the door. Fasten the screws for a secured fit.
8. Next fix the flange into this recess.
9. Place the striking plate on the doorframe and mark its position.
10. With a chisel, carve out a shallow recess.
11. Secure the lock to the frame with screws.

Related articles

• How to hang a door
• How to replace a door frame

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