Liberty Locksmiths Blog

How to Identify the Type of Lock on Your Door

cylinder lock held by Glasgow locksmith

As a Glasgow locksmith I spend a lot of my time replacing locks. Not surprisingly, most people have no idea about the type of lock they have fitted on their front or back door. However, identifying the type of locks you have can sometimes be very important. This is particularly true if you are seeking new home insurance or want to know if you have locks that are vulnerable to lock snapping.

There are a some of the most common locks in use:

1. 5 Lever Mortice Lock

5 lever mortice lock held by Glasgow locksmith

This type of lock is embedded (morticed) into the door and the strike plate is fitted to the frame. This lock is usually only fitted to timber/wooden doors and can only be opened with a key, from either side.

Sometimes 5 lever mortice locks are confused with the less secure 3 lever mortice locks. You can check this by looking on the faceplate of the lock, the number of levers should be stamped there.

For optimum security the 5 lever mortice lock should be Kitemarked and conform to BS3621. If it is, these details should be stamped on the lock faceplate. In fact, many insurance companies require these types of locks to conform to BS3621.

Another useful feature of 5 lever mortice deadlocks is that they can by ‘keyed alike’. This means that if you have this type of lock fitted on both your front and back doors you can use the same key for both.

Sometimes for additional security, front doors with these types of lever mortice locks are also fitted with an additional Nightlatch lock (see below).

2. Nightlatch

nightlatch fitted by Glasgow locksmith

Nightlatch locks are fitted to the inside surface of the door, usually on timber/wooden doors and frames. This type of lock consists of a latch, operated by turning the knob/lever on the inside and by a key from the outside. As with Hoover and vacuum cleaners, the manufacturer Yale has become synonymous with this type of lock. This is why these locks are generally referred to as ‘Yale locks’. There are of course many other manufacturers e.g. Era, Union etc. A few variants of this type of lock exist, with differing levels of security. If the term deadlocking is used, it means that once locked, the lock can only be opened with a key.

Non Deadlocking Nightlatch

This type of lock has a rim cylinder on the outside which needs a key to open but on the inside, a knob/handle is used. Most nightlatches also have a ‘snib’ on the inside which allows you to lock the latch. You can also use it to snib the latch in the open position so that the door doesn’t lock behind you. This type of lock can sometimes be subject to ‘credit card opening’ and is best used alongside a deadlock for extra security.

Key Deadlocking Nightlatch

These locks are very similar to the common non-deadlocking variant but with the added security of being able to deadlock the property from the outside with a key. Once a nightlatch has been deadlocked the latch cannot be slipped with a credit card. This provides a much higher level of security and can also prevent an intruder from smashing a glass door panel to reach in and unlatch the door. However, it is important to remember that with this type of lock, once it has been deadlocked from the outside, the internal handle cannot open the door. This means anyone inside will be locked in.

Double Locking Nightlatch

These locks are very similar but also have a key on the inside which can lock the handle. These are the most secure nightlatches for your front door.

3. Multipoint Locking System

Multipoint locking system for UPVC door fitted by Glasgow locksmith

These locks are most commonly found on composite and uPVC doors e.g. exterior front and back doors, Patio doors, French doors etc. A multi-point locking system bolts the door into the frame and locks at multiple points (hence the name). These bolts are controlled by a single cylinder lock. They can provide a very high level of security.

There are many different types of multipoint locking systems and many manufacturers but all will generally feature a minimum of a centrally located deadbolt and latch and at least two hook bolts, pins or camrollers/mushroom cams. It is however not uncommon to have up to seven locking points systems installed for maximum security.

As mentioned, multipoint locking systems use one locking cylinder (euro cylinder) to engage and lock all points. This means that this type of system can also be ‘keyed alike’ with other cylinder locks e.g. the front door, back door and patio doors can all be locked and unlocked using the same key.

The one weakness in this system has traditionally been the euro cylinder. In the last few years, it has resulted in big increases in the number of break-ins due to a technique known as ‘lock snapping’. Fortunately, there are now ‘anti snap’ euro cylinders available which protect against this.

4. Cylinder Lock

A cylinder lock, also known as a pin tumbler lock uses a series of different length pins, which follow the exact pattern of the key. When the key is inserted, the pins move into the correct position so the key can be turned and the door can be locked or unlocked. There are a number of cylinder locks in use but the most common is the euro cylinder.

Euro cylinder lock

This type of cylinder lock is one of the most popular locks.

 Three of the most common types are

  • The single cylinder, which can be locked from one side only
  • The double-ended cylinder, which can be locked from either side
  • The key and thumbturn option, which locks with a key on the outside and a thumbturn on the inside.

In the past, the biggest problem with this type of lock has been lock snapping.

Lock Snapping

Lock snapping is a technique used by burglars to snap the euro cylinder lock. With the right tool, this can take as little as 20 seconds. The composition and makeup of the standard euro lock made it prone to snapping in the middle section.  To remedy this problem, high security ‘anti-snap’ or ‘snap safe’ versions have now been developed. Rather than snapping in the middle, they’re designed to snap at the end, keeping the central part of the barrel intact.

Oval Cylinder Lock

This is similar to the euro cylinder lock but has an oval shaped barrel and is used with an oval mortice lock case. This type of lock is much less popular than the euro cylinder.

For more tips on keeping your home safe, our friends at have written a helpful article  ‘How to Secure and Prepare Your Home Before Traveling‘.

Liberty Locksmiths is an affordable highly rated locksmith serving customers in Glasgow and the surrounding towns. If you need help upgrading any of your locks to more secure ones please do not hesitate to get in touch. We offer a free quote and fit a range of locks to suit all budgets.

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