Armoured doors in Les Marines flats, and what the extra bolts do

Walk into almost any apartment block along the three kilometres of Les Marines, or a newer block in the centre, and the front door of the flat will be heavier than you expect. It is probably a puerta blindada, an armoured door: a steel sheet or frame inside a timber or laminate face, with a lock that throws bolts in more than one place.

If you have moved into one, or you are renting one for the summer, a few things are worth knowing.

What the extra bolts are

An ordinary door has one bolt that goes into the frame on the lock side. An armoured door usually has:

• several bolts on the lock side, stacked one above the other;
• sometimes bolts at the top and bottom, or into the hinge side;
• fixed hinge-side pins that stop the door being lifted off.

All of the moving bolts are driven by one cylinder, which is why one key does everything.

Why the key needs several turns

Each turn of the key throws the bolts a little further. One turn may only engage them partly; two or more throws them fully. Locking with all the turns is what gives the door its strength. A door that is only pulled shut, on the latch, is barely more secure than an ordinary one.

Looking after it

• Lock it fully whenever you leave, and when you go to bed.
• Do not force the key if it becomes stiff. The cylinder is doing a lot of work; stiffness means it needs attention.
• Watch the alignment. If you need to push or pull the door before the key will turn, the bolts are rubbing on the frame. It gets worse, not better, and eventually strains the mechanism.
• Keep sand out of the keyway. It sounds trivial in a beach flat; it is not.

If you are locked out

An armoured door that was only latched is usually quick to open. One that was double-locked takes longer, because the work is on the cylinder rather than the latch, but the door itself is not damaged. Tell us which it was when you ring.

If you want better security

The weak point of many older armoured doors is the cylinder. Upgrading it to one rated against snapping and bumping is a common and sensible change, and it leaves the rest of the door as it is.