01625 250275 service@cusworth.net

Do you know what locks are fitted to your home?


How do you know they are adequate for your insurer?


By upgrading your door locks, you could save hundreds of pounds on your Buildings and contents insurance!


Insurers, in many cases, ask what type of lock you have  fitted, so you risk invalidating any insurance claim if you wrongly specify your locks fitted to your home.

The descriptions and illustrations below should help you tell which locks are fitted to your home.


Wooden Doors


Rim Nightlatch

Yale Cylinder Rim NightlatchThis is a typical “Yale” cylinder rim nightlatch. It has a single sprung bevelled bolt which locks automatically when the door is closed.


BS 3621 This is a BS3621 automatic deadlocking nightlatch. It is much more secure to the traditional nightlatch for the following reasons:

The lock has a 2nd bolt, which triggers the mechanism – deadlocking the bolt

The bolt is much stronger

The strike plate is larger and can handle higher forces

The cylinder is higher quality, and is protected by a drill resistant shroud

The internal handle can be locked, to prevent  unauthorised opening


Mortice locks


A Mortice deadlock normally has a single rectangular deadbolt. Deadlocks come in a variety of qualities, from 2 or three lever, to 5 lever BS3621 kite-marked locks. There should be clear markings on the fore end showing makers name, and what quality the lock is – 2, 3, 5, lever or BS 3621: 1980 to BS3621: 2007 combined the the kietmark logo.

a 3 Lever Deadlock and strike plate


A 5 lever deadlock generally has a stronger deadbolt and strike plate than a 2 or 3 lever lock

A  B.S. 3621:2007 deadlock showing anti drill plate ans strong deadbolt with at least 20mm  throw and matching boxed strike plate



Sash locks come in the same varieties, with the addition of a latch bolt and lever handles


Five-lever mortice deadlock conforming to (British Standard) BS 3621. This is the highest level of locks  recommended by   the police and insurance companies often specify on your policy. So if you’re thinking of changing your locks, this is the one to go for. The British Standard kitemark must be stamped on the fore end of the lock


Key-operated multi-point locking system. A multi-point locking system has a minimum of three locking points that all lock simultaneously by lifting the door handle and locked by a turn of a key. Multi-point locks are most common on uPVC doors, laminate or patio doors.

Not listed?

If you don’t recognise your locks, then you probably need to have your home security review by a Master Locksmiths Association Company.

To cut costs and improve security, Master Locksmiths recommend you consider getting one of the recognised locks above (unless you’ve got a defined specialist lock, in which case you might need a specialist insurer).or if you feel confident, download the MLA Guide for domestic locking and security


Which lock is best?


If you have either multipoint locks, or BS3621 lock, you should have decent security and lower premiums.


the following is from the money saving expert website:

Can changing your locks cut costs?


The better your lock, the more secure your home is, and the less you pay for your insurance.


We ran some quotes on a price comparison website and the difference in premium between having a five-lever mortice deadlock (preferred by insurers) and a rim automatic deadlatch with key-locking handle with the same insurer, was £48 for the year.


With a five-lever mortice deadlock coming in at about £30 to buy, it’s a no brainer that it’s cheaper to change the locks and get a lower premium with the added comfort of extra security for your home for years to come.


Insurers recommend that the lock is professionally fitted, the cost of which may be similar or higher that the lock itself. But don’t let that put you off, as even if it means the lock doesn’t pay for itself in year one, it’s an investment so it will do in the future.


You can’t just say you have the lock though to get a cheaper premium. If you say you have certain types of locks and you’re burgled, and it turns out these locks don’t work, your insurer may not pay out.