Does Your Door Lock Meet British Standard and Home Insurance Requirements?

Why I have written this guide

Over more than a decade working as a locksmith and property security expert, I have visited thousands of properties. One issue appears repeatedly, particularly in older houses around Beckenham and Bromley: many homeowners believe the front or back door has an “insurance-approved” lock, but have never checked the exact marking or compared it with their policy. Others have checked carefully or asked me to confirm it before deciding what to do.

The lock may work perfectly. It may be a solid older Chubb, Union, Yale or another familiar make. It may even be described as a five-lever lock. None of those facts, on their own, confirms that it meets the standard declared to the insurer.

The reverse is also true. An older lock should not automatically be condemned simply because of its age or brand. Some older locks carry a recognised British Standard marking, and some policies accept more than one type of security arrangement.

This guide is designed to help you identify what is fitted, understand the terminology and ask your insurer the right questions before deciding whether any work is necessary.

The most important point: read your own policy

“Insurance approved” is useful everyday shorthand, but it can be misleading. BSI tests and certifies products against British Standards; an insurer decides what security it requires under its own contract.

Home insurance requirements are not identical. Depending on the insurer, property and cover, the policy or quotation may accept one or more of the following:

• a lock conforming to BS 3621;
• a five-lever mortice deadlock;
• a suitable rim automatic deadlatch;
• a key-operated multipoint locking system;
• existing locks supplemented by key-operated bolts;
• or another arrangement stated in the policy.

Some insurers impose a specific minimum security condition. If they do, the condition may apply particularly to theft or attempted-theft cover and may require the listed devices to be fitted and used when the home is unattended.

Do not assume that every policy requires BS 3621. Equally, do not select “BS 3621” on an insurance form unless you have checked.

What is BS 3621?

BS 3621 is a British security standard for certain locks operated with a key from both the outside and the inside. In homes, it is most commonly found on mortice deadlocks and sashlocks fitted into timber doors.

The current edition is BS 3621:2017+A1:2024. The important point is simple: the standard applies to the complete tested lock, not just the number of levers, the brand or the appearance of the key.

A lock marked as conforming to BS 3621 has been tested for security, strength and durability. The tests cover relevant attack methods and the performance of the complete lock assembly.

What BS 3621 does not mean

However, BS 3621 does not mean that:

• every five-lever lock meets BS 3621;
• a lock is automatically unacceptable because it shows an older edition year;
• every external door needs the same type of lock;
• a BS 3621 lock can make a weak or damaged door and frame secure on its own;
• a key-operated lock is suitable for every escape route; or
• every insurer uses identical wording.

The door, frame, strike plate, hinges, nearby glass and quality of installation all affect security. Even an excellent lock cannot provide proper protection if it is badly fitted or installed in a weak or damaged door frame.

BS 3621, BS 8621 and BS 10621: what is the difference?

BS 3621 — key required on both sides

The BS 3621 standard covers thief-resistant lock assemblies that require a key to unlock from inside as well as outside. Certified BS 3621 mortice locks are available as both mortice deadlocks and mortice sashlocks. A deadlock operates the locking bolt only, while a sashlock combines the deadbolt with a latch operated by door handles. This key-operated arrangement can provide useful security, particularly where a burglar might otherwise reach an internal thumbturn through nearby glazing or a letterbox.

However, needing a key to escape can create a life-safety concern if the key is unavailable during a fire. The suitability of the lock must therefore be considered in relation to the building, the escape route and the people using it.

Examples of BS 3621 mortice locks on timber doors

BS 8621 — keyless escape from inside

BS 8621 covers thief-resistant lock assemblies that allow keyless egress from inside, commonly by a thumbturn or similar operation. These can be more appropriate where rapid escape is important, including some flats, houses in multiple occupation and doors forming part of an escape route.

BS 8621 also covers certified keyless-egress nightlatches. The example below shows a completed upgrade from an existing Yale nightlatch to an ERA BS 8621 Easy Escape nightlatch, followed by the two photographs taken before the upgrade.

BS 10621 — dual-mode operation

BS 10621 covers dual-mode assemblies that can provide normal keyless egress but can be placed into a secure mode in which egress is restricted. These are less common in ordinary homes and require careful selection and use.

How to check whether your mortice lock is marked BS 3621

You can make an initial check in a few minutes.

Step 1: identify the door type

Is the door:

• solid timber;
• uPVC;
• composite;
• aluminium or metal; or
• part of a communal entrance or designated escape route?

BS 3621 is most commonly relevant to single-point locks in timber doors. uPVC and many composite doors usually use a multipoint mechanism and cylinder, so a different description or security standard may apply.

Step 2: open the door and inspect the faceplate

The faceplate is the metal strip on the edge of the door where the bolt emerges. Look for:

• the BSI Kitemark;
• BS 3621;
• a year or amendment reference;
• the manufacturer’s name or logo; and
• any other certification or model marking.

A clear Kitemark and BS 3621 marking are the strongest simple visual indicators. The marking may be small, worn, painted over or partly hidden.

Step 3: do not rely only on “5 lever”

A lock can have five levers without conforming to BS 3621. Conversely, the full assembly and its protective components matter, not just the lever count. “Five lever” and “BS 3621” are not interchangeable descriptions.

Step 4: photograph the complete setup

For a useful remote check, take:

1. a close, sharp photograph of the lock faceplate with the door open;
2. a photograph of the entire edge of the door;
3. a photograph of the inside of the door, showing the lock or night latch;
4. a photograph of the outside keyhole and any security furniture;
5. a photograph of the keep or strike plate in the frame; and
6. a wider photograph showing the complete door and any nearby glass.

Do not include your full address, key code, insurance documents or a detailed photograph of the key blade unless specifically necessary.

Step 5: compare the result with the policy wording

Check the answers previously given to the insurer. Useful search terms in the documents include:

• minimum security;
• security condition;
• door locks;
• theft;
• unoccupied;
• mortice deadlock;
• five lever;
• BS 3621; and
• multipoint locking.

If you are still unsure, send the photographs to a competent locksmith for identification, then ask the insurer to confirm acceptance of the identified arrangement.

What an insurance-standard lock usually looks like

Example A: marked BS 3621 mortice deadlock

What the photograph should show: an open timber door with a close-up of the lock faceplate. The BSI Kitemark and “BS 3621” are legible. The deadbolt projects from the door edge when operated.

Example B: five-lever lock with no visible BS 3621 marking

What the photograph should show: a mortice lock faceplate that carries a manufacturer or “5 lever” marking but no visible Kitemark or BS 3621 reference.

What it means: it may be a serviceable lock, but the photograph alone does not confirm BS 3621 certification. Check the exact model and the insurer’s accepted alternatives.

Example C: older Chubb or Union deadlock

What the photograph should show: the brand and every marking on the faceplate.

What it means: Chubb and Union have produced many different locks over many years. The brand and age alone do not establish current policy compliance. Some older models carry a British Standard marking; others may satisfy an alternative five-lever requirement; others may warrant replacement.

Example D: uPVC or composite door with a multipoint lock

What the photograph should show: the full door edge, hooks or bolts, handles and cylinder.

What it means: do not search only for BS 3621. The insurer may describe this as a key-operated multipoint locking system and may specify a minimum number of locking points. Cylinder security can be assessed separately; TS 007 and SS 312 Diamond are commonly referenced security ratings, but the exact policy wording remains decisive.

Why older Chubb and Union locks need individual assessment

Across Victorian terraces, Edwardian properties and 1930s houses in Beckenham and Bromley, I regularly find older Chubb and Union mortice locks. Many were well made and remain operational after decades.

That does not justify either of the two common shortcuts:

• “It is Chubb, so it must be insurance approved”; or
• “It is old, so it cannot be insurance approved.”

The correct assessment considers:

• the exact standard and year marked on the faceplate;
• whether the marking applies to the complete fitted assembly;
• the lock type and condition;
• the door and frame;
• the quality of the keep and installation;
• whether all necessary parts remain fitted;
• the insurer’s stated alternatives; and
• whether key-operated internal egress is appropriate.

If an older lock is worn, stiff, poorly fitted, missing protective furniture or installed in a split frame, certification history does not remove the practical problem.

What about the year shown after BS 3621?

British Standards are revised over time. You may see an older date after BS 3621 on a lock that was legitimately certified to the edition current when it was made.

Do not infer from the date alone that the lock has “expired”. Ask:

1. Is the Kitemark and standard number genuine and legible?
2. Is the lock complete, serviceable and correctly fitted?
3. Does the insurer require a particular edition, or simply a lock conforming to BS 3621?
4. Has the door or lock been altered since installation?

Where the policy wording is unclear, written confirmation from the insurer is more valuable than an online generalisation.

Common situations where a check is worthwhile

You have just moved home

You normally do not know how many copies of the keys exist or who may still hold them. Previous owners, tenants, agents, cleaners, contractors or neighbours may have had legitimate access at some point.

Changing or rekeying the locks restores key control. It also creates a sensible opportunity to document the existing lock standard, door condition and any necessary upgrade.

You are renewing or changing insurer

The new insurer may ask different questions or apply a different minimum security condition. Verify the answers before accepting the policy.

The markings are missing or painted over

Do not guess. A locksmith may be able to identify the model, but sometimes removal or replacement is the only reliable route.

The lock is difficult to operate

A certified lock that cannot be locked properly is not performing its job. Stiffness may come from wear, door movement, poor alignment or frame problems. Forcing the key can turn a manageable repair into a lockout or broken key.

The door or frame is damaged

A strong lock cannot compensate fully for rotten timber, a loose keep, weak glazing or a split frame. Ask for the complete door set to be assessed.

You have high-value contents or a special security endorsement

Standard consumer advice may not be sufficient. High-value policies can impose specific requirements for locks, alarms, safes or professional installation. Follow the written endorsement and, if necessary, obtain confirmation from the insurer or broker before work.

Should you upgrade if the insurer does not require it?

Possibly, but the recommendation should be proportionate.

An upgrade may be sensible when:

• the existing lock is worn, damaged or unreliable;
• key control has been lost;
• the door has only a basic three-lever mortice lock;
• there is no clear evidence of the declared standard;
• the lock or cylinder is vulnerable to common attack methods;
• the keep or frame needs reinforcement;
• a better arrangement is available without compromising escape; or
• the insurer has imposed a new condition.

Replacement may not be necessary when the existing setup is appropriate, documented, in good condition and accepted by the insurer. A trustworthy assessment sometimes results in “no upgrade needed”. That is advice, not a missed sales opportunity.

The lock is only one part of the door

When I assess an entrance door, I look beyond the badge on the faceplate. A practical check includes:

• door material, thickness and condition;
• frame strength and fixing;
• lock case, bolt and keep alignment;
• hinge condition and hinge-side protection;
• glazing near the lock;
• letterbox position;
• night latch and additional locks;
• multipoint mechanism and cylinder security;
• ease of escape;
• key control; and
• how the household actually uses the door.

Security should work in everyday life. A system that occupants routinely leave unlocked because it is awkward has failed in practice, however impressive the specification sheet looks.

A simple homeowner checklist

Before contacting your insurer or locksmith:

• ☐ Identify every external door and its material.
• ☐ Photograph each door, lock faceplate, frame keep and internal hardware.
• ☐ Record all visible Kitemarks, standards, dates, makes and model numbers.
• ☐ Find your policy schedule, statement of fact and endorsements.
• ☐ Check what lock type you declared when buying the policy.
• ☐ Ask the insurer to clarify any ambiguous wording in writing.
• ☐ Check that every required lock is actually used when the home is unattended.
• ☐ Consider fire escape and key accessibility as well as burglary resistance.
• ☐ Keep invoices and before-and-after photographs for any upgrade.
• ☐ Review key control after moving home, losing keys or changing occupants.

How I can help through WG Locksmiths Ltd

I run WG Locksmiths Ltd, a local, independent, family-owned locksmith and property security company based in Beckenham. I have worked in local homes for over a decade and provide direct, practical advice without call-centre scripts or pressure selling.

From clear photographs, I can often identify:

• the likely lock type;
• visible British Standard markings;
• whether further photographs are needed;
• whether the door uses a mortice or multipoint system; and
• what questions to ask the insurer.

A photograph cannot confirm everything. It may not reveal internal wear, missing components, poor fixing, frame weakness or the complete certification of an altered assembly. Where necessary, an on-site assessment is the proper next step.

Services include lock replacement after moving home, British Standard and insurance-focused lock upgrades, repairs, door realignment, uPVC and multipoint lock work, smart locks and selected home-security improvements.

Send clear photographs by WhatsApp for an initial identification. You will receive straightforward guidance on what appears to be fitted and whether an inspection or upgrade is worth considering. Your insurer remains the authority on the cover it will accept.

Frequently asked questions

Do I legally need a BS 3621 lock for home insurance in the UK?

There is no universal rule that every UK home must have BS 3621 locks. Many insurers ask about BS 3621 or include it among accepted minimum-security options, especially for timber external doors. Your contract, schedule and endorsements determine the requirement for your policy.

How can I tell if my lock conforms to BS 3621?

Open the door and inspect the lock faceplate for the BSI Kitemark and “BS 3621”, usually followed by an edition year. Photograph the marking clearly. Do not rely only on the make, the key shape or “five lever”.

Is every five-lever mortice lock BS 3621?

No. A five-lever mechanism alone does not prove that the complete lock assembly meets BS 3621. Look for the Kitemark and standard marking, then check the policy wording.

Are old Chubb deadlocks still insurance acceptable?

Some may be; some may not be. Chubb produced numerous models and British Standards have changed over time. Check the exact marking, condition, installation and the insurer’s accepted lock descriptions. The brand name alone proves nothing about a specific fitted lock.

Does an older BS 3621 date mean the lock has expired?

Not automatically. A lock may carry the edition current when it was certified. Whether the insurer accepts it depends on its wording and the condition and completeness of the installation. Ask the insurer if it requires a particular edition.

What bolt length should a BS 3621 mortice deadlock have?

The commonly cited modern requirement is a deadbolt projection of at least 20 mm for relevant mortice designs, but a homeowner should not try to certify a lock from bolt length alone. Certification concerns the complete tested assembly.

Is BS 3621 suitable for a flat entrance door?

Not in every case. Because BS 3621 normally requires a key for exit, fire safety and means of escape must be considered. BS 8621 keyless-egress hardware may be more suitable in some settings, subject to the building, lease, fire strategy and insurer’s requirements. Communal doors and flat entrance doors should not be altered casually.

Do uPVC and composite doors need BS 3621 locks?

They commonly use key-operated multipoint locks rather than a traditional mortice deadlock. Insurers may ask about the number of locking points. Cylinder and handle security may also be relevant, with standards such as TS 007 or SS 312 Diamond often used in security guidance. Check the exact policy.

Can a night latch meet BS 3621?

Some complete rim-lock or automatic deadlatch assemblies can conform to BS 3621. A basic night latch does not automatically meet the standard. Look for certification on the complete product and ensure all specified security components are present.

Will my insurer refuse a burglary claim if I have the wrong lock?

It depends on the policy, the information provided when cover was arranged, any minimum-security endorsement and the circumstances of the loss. Do not assume automatic refusal, but do not ignore a stated condition. Contact the insurer or broker for an interpretation of your contract.

Should I change the locks after moving house?

It is normally sensible because you cannot know how many valid key copies remain in circulation. A move-in lock change also provides a good opportunity to document the door security and compare it with the new policy.

Can a locksmith guarantee that my insurance is valid?

No. A locksmith can identify hardware, assess condition and installation, and fit products to an appropriate specification. Only the insurer can confirm that a particular arrangement satisfies its contract and that cover applies to a particular claim.

What photographs should I send to WG Locksmiths?

Send the lock faceplate and markings, the entire door edge, both sides of the lock and handle, the frame keep and one full-door photograph. For a uPVC or composite door, include the full multipoint strip and cylinder. Avoid sending your address, policy number or a detailed key-blade image unless required.

Can WG Locksmiths check my lock from a photograph?

I can often provide an initial identification from clear photographs and explain the likely next step. A photo assessment cannot verify concealed wear, fixing quality, internal components or the insurer’s contractual decision.

Final advice from Paul

Do not wait until a burglary claim to discover that the lock description on your insurance documents does not match the door.

Check the marking, check the whole door, check what you told the insurer. Ask for written clarification where necessary. Then upgrade only if there is a genuine security, reliability or policy reason.

That calm, evidence-based approach usually costs less than guessing—and provides far more useful reassurance.

Sources

1. British Standards Institution, BS 3621:2017+A1:2024 – Lock assemblies operated by key from both the inside and outside of the door
2. Master Locksmiths Association, What are BS 3621 British Standard locks?
3. Association of British Insurers, Insurance advice on home security
4. Association of British Insurers, Cutting the cost of home insurance
5. Allianz UK, Stay insured with the right house locks
6. LV=, Home insurance security requirements
7. Admiral, A guide to house door lock types
8. Thames Valley Police, Secure your home – keep burglars out
9. Ask the Police, Home Security – Doors and Windows
10. Union, What are BS 3621 locks?