Escaping fire under lock and key

Lucy Greenslade unpicks a few more questions about locks and home security.

Being burgled is bad enough, but it’s far worse if you then discover that your insurance is invalid because you failed to use adequate locks at all times. Read the small print of your policy – although, to be fair to insurers, it’s often underlined or in bold or large print. The likelihood is you’ll find a reference requiring “a 5-lever mortice lock conforming to BS 3621 on all exit doors and key operated locks on all ground floor and accessible windows.”

A five lever mortice lock
A five lever mortice lock

In lock-language, a ‘lever’ is simply a shaped and moveable part inside a lock. Its movement is controlled by two things: a pivot and one of the prongs on a key. Internal locks often have only three levers but, for security, exterior locks require five. If all five levers are not moved to their correct positions by the key, then the mortice-bolt will not move across to allow the door to open.

Most of us expect to see two different types of lock on a front door. One will be a mortice lock, generically often known as a ‘Chubb’ lock. The other, usually higher up on the door, will be a nightlatch and is generically known as a ‘Yale’ lock. The mortice lock is set into the edge of the door so that its body is entirely housed within the thickness of the period front doors. When operated, the bolt of the mortice lock moves across into a steel housing secured into the jamb of the door frame.

A nightlatch is surface-mounted and has a sprung latch which slides automatically into its keep on the frame whenever the door closes. You can accidentally lock yourself out with a rimlock if the victorian front door slams and you haven’t got the key in your pocket.

A double locking nightlatch
A double locking nightlatch

There are actually two British Standards for Thief Resistant locks protecting private dwellings. BS 3621 2007 specifies a standard for locks with “key egress”. BS 8621 2007 applies to locks offering “keyless egress”. Now ‘egress’ is just a fancy word for departure, or going out. The distinction between keyed and keyless egress becomes relevant when escaping from fire is considered. If your home is a typical ‘single-family dwelling’ with only a ground and a first floor, then there are no fire regulations regarding ‘Means of Escape’ in the event of a fire. If you undertake a loft-conversion so that your house now has three-storeys, the Building Regs will require a fire-protected stairway from the top of the house to the final exit. Additionally, if you live in a house divided into separate flats or dwellings, which are all accessed from a communal stairway, then the fire regulations regarding properties ‘in multiple occupancy’ require “keyless egress” from the final exit (usually the communal front door).

So, in a single-family dwelling, your front door should have both a five-lever mortice deadlock and a nightlatch with a key-locking handle on the inside. If you are worried about escape from fire in the middle of the night, either hide a set of keys in the hallway or don’t deadlock the door at bedtime, but rely instead on traditional, hand-operated, shoot bolts to lock yourself in. Remember, ‘though, if you resort to shoot bolts, anyone coming home ‘after lights out’ will have to wake you to let them in!

Where a building is in multiple-occupancy, the communal entrance door can still have a 5-lever mortice lock but this can only be key-operated from outside. On the inside it must have a handle (often called a ‘thumb-turn’) and, of course, the nightlatch cannot have a key-operated handle on the inside either.

Bespoke Front Door

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