Deadlocks

Aged Brass 2½" 5 Lever BS Dead Lock, from our current range.

What is a deadlock?

A deadlock is a mortice lock with no latch and no handle mechanism – it operates purely by key, locking and unlocking the bolt directly. Because there is no spring latch to hold the door shut day to day, a deadlock is normally fitted as a secondary lock alongside a handle-operated latch or sashlock, adding an extra layer of security that can only be released with a key, from either side of the door.

This makes deadlocks a popular choice for anyone wanting genuine dead-bolt security in addition to everyday latch convenience elsewhere on the door.

Where deadlocks are used

• Front and back doors – commonly fitted above or below a sashlock or night latch for extra security
• French and patio doors – deadlocks are frequently specified on double doors alongside flush bolts on the inactive leaf
• Rental and let properties – a straightforward, key-only lock that landlords can rekey between tenancies

Choosing the right deadlock

A few practical points are worth checking before you buy:

• British Standard certification – BS3621 or equivalent is often required by insurers for external doors
• Case size – commonly 2½" or 3", matched to your door's stile and any existing mortice
• Keyed alike – deadlocks are available in keyed alike sets for properties with several doors

Related products

Browse our current range in Locks & Latches, or see the related Sashlocks and Mortice Locks guides.

Frequently asked questions

Why would I need a deadlock as well as a sashlock?

A sashlock's latch alone is not usually considered high security, since it can be opened without a key from outside in some situations. A deadlock adds a bolt that can only be operated by key, giving genuine extra security.

Can a deadlock be locked from both sides?

Yes, a deadlock requires a key to lock and unlock from either side of the door, unlike a thumbturn cylinder which allows quick release from the inside.

Do deadlocks come in keyed alike sets?

Yes, many ranges offer deadlocks keyed alike, so a single key operates every deadlock on a property, useful for multiple doors or outbuildings.

Back to the Locks & Security Guide, or explore the full Knowledge Centre.