Types of Door Locks Explained

## Starting with the basics

There are four types of door lock you will encounter on London properties: rim latches (often called Yale locks), mortice deadlocks, euro cylinder locks, and multi-point UPVC systems. Understanding what each one does tells you whether your door is actually secure.

Rim latches (Yale locks)

A rim latch mounts on the inside face of the door. When you pull the door shut, the spring-loaded bolt engages automatically. You open it from outside with a key and from inside with a knob or lever.

The problem: a standard rim latch can be opened with a credit card in under 10 seconds. They offer almost no resistance to forced entry. Fitting one and calling it a "front door lock" is a false sense of security.

Upgraded versions — rim deadlocks — require a key to operate both ways and cannot be slipped with a card. These are more appropriate as a secondary lock.

Mortice deadlocks

A mortice lock fits into the edge of the door (morticed into the wood). The bolt must be manually operated with a key to lock and unlock — it does not engage automatically. This is the meaningful difference.

A BS3621 5-lever mortice deadlock is what most home insurers require. The bolt throws 25mm and is hardened against attack. It is also difficult to pick because of the levers. These locks have been standard on British front doors for decades for good reason.

If your front door has only a Yale latch and no mortice, your insurance policy may not pay out after a break-in.

Euro cylinders

Euro cylinders are the oval-shaped lock cores used in modern UPVC doors and many aluminium doors. The cylinder is what the key turns. The lock mechanism itself is inside the door.

Standard euro cylinders are vulnerable to a technique called cylinder snapping — an attacker grips the exposed part of the cylinder with pliers and snaps it off, exposing the mechanism. This takes about 20 seconds and requires no skill.

An anti-snap euro cylinder has a weak point engineered at a position that does not compromise the lock's function. When it snaps, the internal mechanism is unaffected. These are the minimum standard for any UPVC door.

Look for TS007 3-star ratings when buying a euro cylinder. Anything below that is a risk.

Multi-point UPVC systems

UPVC doors use a multi-point system — turning the handle engages three or five locking points along the door edge simultaneously. This spreads the load across the frame, making kick-in attacks much harder.

The weak point in UPVC systems is the gearbox inside the door that operates these locking points. When it fails, the door either will not lock or the handle drops. Gearbox failures are common after 10–15 years and are a straightforward repair.

Which combination do you actually need?

For a timber front door: a BS3621 5-lever mortice deadlock plus a rim latch for convenience. The mortice does the security work; the latch handles everyday use.

For a UPVC door: a TS007 3-star anti-snap euro cylinder in a multi-point system. Check the cylinder — many UPVC doors are fitted with standard cylinders when installed.

For a back door or secondary door: at minimum a single-point deadlock. Sliding patio doors need a patio lock or bar lock in addition to the built-in handle mechanism.