Which lock does my insurance company require?

Most UK home insurance policies require a BS3621 five-lever mortice deadlock on wooden external doors. For uPVC and composite doors, the requirement is less specific — insurers generally require the door to be locked with the key. However, policies vary, so check your specific wording or call your insurer directly.

Can I have a smart lock and still meet insurance requirements?

It depends on your policy. Some modern policies accept smart locks, but many still reference BS3621 or traditional mechanical locks in their terms. I would recommend checking with your insurer before removing a traditional lock in favour of a smart one. The safest approach is to keep your mechanical lock and add smart features on top.

Is an anti-snap lock better than a BS3621?

They are designed for different doors and address different threats. A BS3621 mortice deadlock is for wooden doors and resists picking, drilling, and forced entry. An anti-snap euro cylinder is for uPVC and composite doors and resists snapping, the most common attack on those door types. You cannot fit a BS3621 to a uPVC door or an anti-snap cylinder to a standard wooden door.

What is the best overall lock for a front door?

For a uPVC or composite front door, an Ultion or Avocet ABS anti-snap cylinder is the best option. For a wooden front door, a BS3621 five-lever mortice deadlock fitted properly with a reinforced strike plate. In both cases, the lock is only as good as the door and frame it is fitted to.

BS3621 vs Anti-Snap vs Smart Lock: Which Security Standard Actually Matters?

There are dozens of lock standards and security ratings. Here is a plain-English comparison of the three that actually matter for your front door.

Three Approaches to Door Security

If you're looking to upgrade your home security, you'll quickly run into three main options: BS3621 mortice deadlocks, anti-snap euro cylinders, and smart locks. Each has its place, and the right choice depends on what type of door you have and what you're trying to achieve.

I'm Ross, a locksmith based in Coventry, and I fit all three types regularly. Here's my honest breakdown — no sales pitch, just practical advice based on what I see on the ground every day.

BS3621 Mortice Deadlocks

What They Are

A BS3621 mortice deadlock is a heavy-duty lock that sits inside the body of a wooden door. It has a chunky deadbolt that throws at least 20mm into the door frame, and it meets the British Standard BS3621 — the benchmark that most insurance companies require.

Where They're Used

BS3621 locks are designed for **wooden doors only**. You'll find them on traditional front doors, period property doors, and wooden back doors. They're the standard security lock for any timber door.

Key Features

**5-lever mechanism** — the key has to lift five internal levers to the correct height before the bolt will move

**20mm deadbolt throw** — the bolt extends at least 20mm into the frame

**Anti-pick features** — curtain or false notches to resist picking

**Anti-drill protection** — hardened steel inserts in the bolt and body

**BSI Kitemark** — independently tested and certified

Pros

Insurance approved — virtually all home insurance policies recognise BS3621

Extremely secure when properly fitted with a reinforced strike plate

No batteries or technology to fail

Proven technology — these locks have been protecting homes for decades

Cons

Only suitable for wooden doors (not uPVC or composite)

Requires a rectangular hole cut into the door body — fitting is more involved

You need a key to lock from inside (fire safety consideration)

Can be expensive to fit if cutting a new mortice — see my [five-lever mortice guide](/blog/five-lever-mortice-deadlock-guide) for details

Cost

I fit BS3621 mortice deadlocks from £79 including the lock and fitting. If there's an existing mortice in the door, it's a straightforward swap. If I need to cut a new mortice, it takes longer and costs more. Check the [prices page](/prices) for details.

Anti-Snap Euro Cylinders

What They Are

Anti-snap euro cylinders are replacement lock barrels designed to resist [lock snapping](/blog/what-is-lock-snapping) — the most common burglary technique in the UK. They fit into the existing multipoint locking mechanism on uPVC and composite doors.

Where They're Used

Anti-snap cylinders are for **uPVC and composite doors**. If your door has a euro cylinder (the oval-shaped lock you put your key into), you can upgrade to an anti-snap version.

Key Features

**Sacrificial break point** — designed to snap in a controlled way that keeps the door locked

**Anti-drill, anti-pick, anti-bump** — multiple layers of attack resistance

**TS007 rated** — the relevant British Standard for euro cylinders (read my [TS007 vs SS312 guide](/blog/ts007-vs-ss312-lock-standards) for more)

**Quick to fit** — a direct replacement for your existing cylinder

Pros

Directly addresses the biggest burglary threat to uPVC and composite doors

Quick and affordable to fit — typically 15-20 minutes

No door modification needed

Multiple brands and price points available ([see my comparison](/blog/anti-snap-locks-compared))

Cons

Only relevant for doors with euro cylinders

The cylinder is only part of the picture — the multipoint lock mechanism matters too

Quality varies enormously between brands

Not all anti-snap cylinders carry full 3-star certification

Cost

I fit anti-snap euro cylinders from £69 for a standard [lock change](/services/lock-change). Premium options like Ultion are more. Call 07735 336175 for a quote on your specific door.

Smart Locks

What They Are

Smart locks let you lock and unlock your door using a smartphone, key fob, PIN code, or fingerprint instead of (or as well as) a traditional key. Some replace the entire lock; others add smart functionality to an existing mechanism.

Where They're Used

Smart locks are available for both wooden doors and uPVC/composite doors, depending on the model. The Yale Conexis L2 fits euro cylinder doors. Smart mortice locks exist but are less common in the UK market.

Key Features

**Keyless entry** — no more fumbling for keys

**Remote access** — lock/unlock from anywhere via an app (with a WiFi bridge)

**Access sharing** — send virtual keys to family, guests, or tradespeople

**Activity logs** — see when the door was locked and unlocked

**Auto-lock** — some models lock automatically after a set time

Pros

Convenient, especially for families and rental properties

Useful if you frequently need to give access to others

Some models maintain full mechanical security alongside smart features

Modern and increasingly reliable

Cons

**Battery dependent** — if the batteries die, you could be locked out

**Technology risks** — software bugs, Bluetooth/WiFi interference, potential hacking

**Insurance grey area** — not all insurers accept smart locks as meeting their requirements

**Cost** — quality smart locks start around £150-200 for the unit alone, plus fitting

**Complexity** — more moving parts means more that can go wrong

Cost

A quality smart lock fitted typically costs £200-350 including the lock and installation. Budget options exist but I'd be cautious — security isn't where you want to cut corners.

Which One Is Right for Your Door?

The decision is actually simpler than most people think:

Wooden front door? You need a BS3621 mortice deadlock. Your insurance almost certainly requires it. If you also want a nightlatch (Yale-type lock) for convenience, fit both — see my [Yale vs mortice guide](/blog/yale-vs-mortice-deadlock).

uPVC or composite door? You need an anti-snap euro cylinder at minimum. This addresses the single biggest vulnerability on your door. It's affordable, quick to fit, and makes a genuine difference.

Want keyless entry? A smart lock can work alongside either of the above, but I wouldn't rely on one as your only security measure. If you want smart features on a uPVC door, the Yale Conexis L2 is the most proven option in the UK market. Read my [smart locks guide](/blog/smart-locks-2026-are-they-secure) for the full picture.

Insurance Implications

This is where it gets important:

**BS3621** — accepted by virtually all UK home insurers. If your wooden door doesn't have one, you may not be covered for theft.

**Anti-snap cylinders** — most insurers don't specifically require them (yet), but having one fitted shows due diligence and can support a claim.

**Smart locks** — check with your insurer before relying on one. Many policies still reference BS3621 or equivalent mechanical locks. A smart lock might not meet the wording of your policy.

My advice? Meet your insurance requirements first, then add any extras you want on top. If you're unsure what your policy requires, call your insurer and ask. Then call me on 07735 336175 and I'll make sure your doors are up to standard.

My Recommendation for Most Coventry Homes

Most homes in [Coventry](/areas/coventry-city-centre) have a combination of door types. A typical setup I'd recommend:

**Front door (uPVC/composite):** Anti-snap euro cylinder — Avocet ABS or Ultion

**Front door (wooden):** BS3621 five-lever mortice deadlock plus a nightlatch

**Back door (uPVC):** Anti-snap euro cylinder

**Back door (wooden):** BS3621 deadlock at minimum

For a full assessment of your home's locks, call 07735 336175 or check the [services](/services/lock-upgrade) I offer. I cover all areas of Coventry and can usually attend the same day.

BS3621 vs Anti-Snap vs Smart Lock: Which Security Standard Actually Matters?

Three Approaches to Door Security

BS3621 Mortice Deadlocks

What They Are

Where They're Used

Key Features

Pros

Cons

Cost

Anti-Snap Euro Cylinders

What They Are

Where They're Used

Key Features

Pros

Cons

Cost

Smart Locks

What They Are

Where They're Used

Key Features

Pros

Cons

Cost

Which One Is Right for Your Door?

Insurance Implications

My Recommendation for Most Coventry Homes

Frequently Asked Questions

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