Locks and doors · 1 September 2026 · 5 min read
Why Your Sliding Terrace Door Stopped Locking
Worn rollers, a keeper out of line, grit in the track or a tired latch. How to tell which it is on your Alicante terrace door, and what you can fix yourself.
In a flat with a terrace, the sliding door is the one used most in summer and thought about least in winter. Then one day you slide it shut, push the handle down, and nothing catches. Here is how to work out why.
Why Alicante is hard on sliding doors
AEMET records around 2,851 hours of sunshine a year in Alicante. An aluminium frame expands and contracts with the heat every single day, and a latch adjusted in January may be a few millimetres out in August. Add average humidity of 66 per cent, salt on the air near the sea and sand carried in from the beach, and the running gear of a sliding door works hard.
Four likely causes
1. The door has sunk
The door rides on rollers in the bottom of the sash. When they wear, the whole door drops a few millimetres and the hook of the lock passes underneath the keeper on the frame. Sign: the door is harder to slide, and it locks if you lift the handle side slightly.
2. Grit in the track
Sand and dust in the bottom track lift one end of the door or stop it closing fully. Sign: a grinding noise, and a gap at the top or bottom when shut.
3. The keeper has moved
The metal plate on the frame that the hook catches is held by two screws. Heat, slamming and time loosen them. Sign: visible scratches around the keeper where the hook is hitting it.
4. The lock itself has failed
Springs break and small parts wear out inside the lock. Sign: the handle feels loose or moves without resistance, and the hook does not come out at all when you move it with the door open.
What you can do yourself
- Vacuum the track, then wipe it with a damp cloth. Never oil it: oil catches sand.
- Check the keeper screws and tighten them if they are loose.
- Watch the hook with the door open while you move the handle. If it comes out properly, the lock is fine and the problem is alignment.
When to call someone
If the door has sunk, the lock mechanism has failed, or you cannot lock a door that opens onto a reachable terrace or garden, it needs a repair. Rollers, hook locks and keepers are replaceable parts, and a door that will not lock can usually be made secure the same day even if a part has to be ordered.
For the full list of what can be repaired, see aluminium and uPVC door locks.