These instructions will show you how to change the door lock on a room door. Find out here how to correctly remove the mortise lock step by step and install a new lock.
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Changing the door lock – what should you pay attention to?
With frequent use, door locks, like common mortise locks, wear out. The lock starts to get stuck, gets stuck or can no longer be opened or closed at all. You should replace the door lock in time to continue using the door smoothly. You also save on expensive locksmith services and maintain the security of your home.
Door locks are available in different designs for locks for interior, apartment and front doors. Simple warded locks are usually used for doors inside the apartment. House and apartment doors have tubular frame locks, mortise locks, security locks or self-locking locks.
Find out now in the step-by-step instructions how to determine the size of the lock cylinder and find out which cylinder you need to replace the door lock. Then remove the lock cylinder and the door handle to take out the old door lock. Finally, you install the new door lock using the instructions in the same way as you removed the old door lock, only in reverse order. In addition to the instructions, our video shows you exactly how to do this.
7 steps to Change door lock
1. Determine the size of the lock cylinder
At a glance
- Measure the old lock cylinder
- Determine the dimensions of the old door fitting
That's how it goes
Open the door and look at the lock on the edge, also known as the door rebate. The adjusting screw is located directly under the latch at the level of the cylinder. Starting from the screw, measure in both directions to the end of the fitting. Write down the inside length and the outside length. These values result in the required size of the locking cylinder.
Note: Door leaves are usually constructed asymmetrically and require cylinders with sides of different lengths. That's why it's important to measure both sides. However, you can later use the lock cylinder in both directions. For example, you can buy a double cylinder with the values 30/40 or 40/30. The only exception is the knob cylinder: here the inside length must correspond to the knob side length.
If you want to replace the door fittings at the same time as replacing the door lock, then also determine the distance from the centre of the cylinder up to the centre of the doorknob or door handle.
Tip: The value is often 72 mm or 92 mm.
2. Loosen the adjusting screw and remove the locking cylinder
At a glance
- Unscrew the adjusting screws
- Remove the cylinder with key
That's how it goes
When replacing the door lock, unscrew the adjusting screw completely. Then remove the lock cylinder by turning the key about 20° to the right or left.
If the locking cylinder is stuck, you can loosen it by shaking it slightly. If the cylinder is really tight, it often gets stuck on the fitting. Slightly loosen the screws on the fitting and try to remove the lock cylinder again. If the removal doesn't work at all, you have to remove the fitting - but depending on the door fitting and lock, this is necessary anyway.
3. Remove the door handle and square
At a glance
- Remove door handle
- Remove square
- If necessary, unscrew door fittings
That's how it goes
Now remove the door handle and the key and take out the square that is attached to it or inserted individually. The latter runs through the entire thickness of the door, the lock and the fittings and moves the lock using the handle.
If necessary, remove the protective fittings to remove the square. To do this, loosen the screws and pull off the fittings. Depending on the manufacturer, the covers of the protective fittings are attached or secured with small screws, which you also unscrew. The same applies to the possible hexagon socket screw on the underside of the handle, with which the square is fixed.
4. Remove the mortise lock
At a glance
- Remove the screws on the lock
- Take out the door lock
That's how it goes
Once the square has been removed, loosen the two screws at the top and bottom of the lock - they are again on the door rebate side. Now you can pull out the lock and take it with you as a sample when buying a new one.
5. Install a new lock
At a glance
- Insert door lock
- Fix screws
That's how it goes
The new lock is installed in the reverse order of removal. So you first insert the new door lock into the milling on the door rebate side and fix it with the top and bottom screws.
6. Install fittings and square
At a glance
- Screw on protective fittings
- Insert square, fix and test
That's how it goes
Now mount the removed fittings and put the square or the handle together with the square back on. If necessary, fix it with the Allen screw at the bottom of the handle when installing. Then you test whether the square turns when you press it.
7. Tighten the adjusting screw
At a glance
- Insert cylinder with key
- Tighten the adjusting screw
- If necessary, drill holes for new door fittings
That's how it goes
Now put the cylinder back in the correct direction according to the values determined before removal. Test all locking functions with the key and finally tighten the adjusting screw. If you want to replace the door fittings at the same time, they often require different drill holes. Use a drilling template to carry out these holes.
Note: When choosing new door fittings, make sure that existing holes are covered and that there is enough door material for fastening.
Tip: Increase the security of your front door with an additional lock and a door viewer. Both elements are easy to assemble and make your apartment or house even safer.
