Changing Your Front Door Lock in 4 Steps

Moving in, lost key, tired lock: changing a front-door cylinder is within reach of a careful DIYer. Here is the four-step method.

Step 1: identify and measure

With the door open, measure the cylinder from the fixing screw (faceplate) to each face: these two dimensions (e.g. 30 × 40 mm) determine the reference to buy. Note the type too: a euro cylinder in 90% of cases, thumb-turn inside if you want keyless exit.

Step 2: remove the old cylinder

1. Undo the faceplate screw located under the latch.
2. Insert the key and turn it slightly (about 15°) to align the cam.
3. Pull the cylinder: it slides out of the case.

Step 3: fit the new one

Slide the new cylinder in with the cam aligned, refit the screw without forcing, and check the key operates freely with the door open, over several full turns.

Step 4: test before closing

Test all the locking points with the door open then ajar. A key that catches signals a misaligned cylinder: loosen the faceplate screw a quarter turn.

When is a professional the better choice?

Integrated multipoint lock, security door, encased lock or a door that has dropped: replacement then requires specific skills and parts. Choose an A2P-certified anti-snap cylinder with an emergency function if a key may stay inside. Our locksmiths replace cylinders and locks throughout Île-de-France, with a free quote and the price announced before work.