How Secure Are Your Door Locks?

Traditional front door locks, often referred to as ‘yale locks’ (the correct term is’ Nightlatch’) are particularly vulnerable to a technique known as ‘lock bumping’.  The locks used in double glazed doors are equally vulnerable and can also be attacked by a technique called ‘lock snapping’.  In both cases it can take only a matter of seconds for the burglar to disable the lock.   If your door locks are more than ten years old you should consider replacing them with more secure fittings.

What is Lock Bumping?

Lock bumping is the name given to a technique which is widely used by locksmiths in order to open pin tumbler locks when people have lost their keys and are locked out of either their home or workplace. 

Unfortunately due to the Internet the technique has become public knowledge, and it is now being used by burglars to break into properties usually leaving no evidence that a break in has occurred, making insurance claims very difficult.

There are lots of videos on YouTube showing how to make bump keys and how to bump locks.  There are also lots of websites on the Internet selling ready made bump keys and bump hammers.

How does Lock Bumping work?

A typical pin tumbler cylinder usually consists of five main parts, the body, the plug, the key way, upper pins, lower pins and springs.  When the correct key is inserted into the key way in the plug the upper and lower pins will line up at what is known as the shear line.  This then creates a slight gap between the body and the plug which will allow the plug to rotate inside the body and open the cylinder.

Lock bumping involves using a specially cut key where all the grooves on the key have all been reduced to their lowest point.  When inserted into a cylinder with a matching key way and struck with a suitable object it allows the transfer of kinetic energy through the upper pins and into the lower pins.  This action allows them to all jump up at the same time and then for a split second settle at the shear line.  If the key is turned very slightly at the right moment when the pins clear the shear line it will allow the cylinder to open, in the same way as it would do if the correct key was inserted and used.

If your door has a traditional ‘yale lock’ then consider replacing it.  Make sure that the new lock conforms to BS1/BS2 - BS3621.  An example is the BS1/BS2 - BS3621 Maximum Security Nightlatch.

What is Lock Snapping?

Lock snapping is a very common method used by burglars to break into a property that has a euro cylinder lock.  Most UPVC doors use euro cylinder locks.

Lock snapping involves snapping the lock cylinder in two, by applying force, and removing the outside part to expose the lock mechanism.  Doing so provides access to the mechanism, allowing the door to be unlocked.  Thieves use tools like hammers and screwdrivers to snap the locks and, worryingly, it can take just seconds to gain access.  This technique does not require experience or skill, merely brute force.

The locks most at risk of this type of attack are fitted with a euro profile cylinder.  Euro profile locks are found in the majority of UPVC and composite doors and operate in combination with a multipoint lock.

To combat this threat simply upgrade your cylinder to one that is specifically designed to prevent this method of attack, ideally one that meets the TS007 3 Star standard.  For more information see the guide produced by the Door & Hardware Federation, together with the Glass & Glazing Federation.

See also the Master Locksmiths Association website.

For complete door assemblies the relevant standard is PAS24.  Bump and snap resistant cylinders did not become a requirement of PAS 24 until 30th November 2008.  So if your doors were installed more than ten years ago, it might be a good idea to consider upgrading the locks.