Your home insurance probably has requirements about your door locks. Meeting these requirements protects your coverage—failing to meet them could leave you unprotected precisely when you need insurance most.
This guide explains what insurers typically require and how to ensure compliance. For a complete overview, see our locks and insurance guide.
Why Insurance Cares About Locks
Risk Management
Insurance is fundamentally about risk. Your locks affect:
| Factor | Insurance Impact |
|---|---|
| Break-in likelihood | Higher with poor locks |
| Claim probability | Directly correlated |
| Premium pricing | May reflect lock quality |
| Policy conditions | Lock requirements |
The Insurance Logic
- Better locks = fewer break-ins = fewer claims = sustainable premiums
- Lock requirements shift some security responsibility to you
- Compliance conditions allow fair claim assessment
"Insurance requirements aren’t arbitrary bureaucracy—they’re based on what actually prevents break-ins. BS3621 exists because locks meeting that standard genuinely resist attack.
Common Policy Requirements
Front Door
Typical requirement:
“A 5-lever mortice deadlock or sashlock conforming to BS3621”
What this means:
- 5 levers inside the mechanism
- Mortice (fitted inside door body)
- Deadlock (key-only) or sashlock (key + handle)
- BS3621 certified
Back and Side Doors
May specify:
- Same BS3621 requirement as front
- Or “key-operated lock”
- Sometimes less stringent than front door
French Doors and Patio Doors
Often require:
- Key-operated locks on both doors
- Multi-point locking on modern types
- Key operation, not just bolt or handle
Windows
Common requirements:
- Key-operated locks on opening windows
- Ground floor and accessible windows particularly
- Often less precisely specified than doors
Understanding BS3621
What It Certifies
BS3621:2007 is the British Standard for high-security locks. Certification requires:
| Feature | Requirement |
|---|---|
| Levers | Minimum 5 |
| Key combinations | Minimum 1,000 differs |
| Bolt throw | Minimum 14mm |
| Anti-drill | Hardened elements |
| Anti-saw | Bolt protection |
| Anti-pick | Internal features |
How to Identify
On the lock:
- Kitemark on faceplate
- “BS3621” marking
- Manufacturer’s certification number
On your key:
- 5 distinct cuts on the blade
What It Doesn’t Cover
BS3621 is for mortice locks. It doesn’t apply to:
- Euro cylinders (different standards—TS007). See our anti-snap cylinder guide for details.
- Rim locks (Yale-type)
- Digital/smart locks (various standards)
Finding Your Requirements
Where to Look
Policy schedule:
- Lists property-specific conditions
- May reference security requirements
Policy booklet:
- General conditions section
- Security requirements section listed
Certificate of insurance:
- Summary that may reference lock requirements
Key Phrases to Find
- “Security conditions”
- “Locks and keys”
- “BS3621”
- “5-lever mortice”
- “Key-operated locks”
Checking Your Compliance
Audit Your Doors
For each external door:
| Door | Lock Type | Levers | BS3621 Marked? |
|---|---|---|---|
| Front | |||
| Back | |||
| Side |
Identifying Lock Type
Mortice lock: Keyhole in door face, lock sits inside door body Rim lock: Lock box visible on inside of door (surface mounted) Multipoint: Euro cylinder, handle-operated, multiple locking points
Counting Levers
Look at your key:
- Count the distinct cuts on the blade
- 5 cuts = 5 levers (compliant)
- 3 cuts = 3 levers (non-compliant for BS3621)
What Happens If Non-Compliant
Claim Scenarios
Break-in through non-compliant door:
- Insurer may reduce payout proportionally
- May deny claim entirely in serious non-compliance
- Will depend on policy wording and circumstances
Break-in through compliant door/window:
- Lock compliance less directly relevant
- Other factors may apply
Non-break-in claim (fire, flood, etc.):
- Lock compliance typically irrelevant
- Different policy conditions apply
Upgrading for Compliance
Cost of Compliance
| Upgrade | Typical Cost |
|---|---|
| BS3621 sashlock fitted | £100-180 |
| BS3621 deadlock fitted | £80-140 |
| Anti-snap cylinder (if applicable) | £60-120 |
| Full front door upgrade | £150-250 |
Time to Compliance
- Single lock replacement: 30-60 minutes
- Multiple door upgrade: Half day
- Usually same-day service available
Documentation
After upgrade:
- Keep fitting receipt
- Note locksmith details
- Photograph certification marks
- Store with insurance documents
Special Situations
Listed Buildings
If you can’t fit BS3621 locks due to:
- Conservation requirements
- Original door furniture constraints
- Building regulations
Action:
- Contact insurer before claim situation
- Explain constraints in writing
- Request policy endorsement
- Document what security you do have
Non-Standard Doors
Composite doors, uPVC doors with Euro cylinders:
- BS3621 may not apply
- TS007 for cylinders may be referenced—see our guide on understanding lock grades
- Check policy for specific requirements
- Ask insurer if unclear
Multiple Entry Points
If your property has many doors:
- Check if all require BS3621
- Side and rear may have different requirements
- Communal entrances may have special conditions
Frequently Asked Questions
What lock does home insurance typically require?
Most policies require a 5-lever mortice deadlock or sashlock meeting BS3621 on main entry doors. Some accept key-operated locks to equivalent standard. Check your specific policy wording.
Will my insurance pay out if my locks don't meet requirements?
Depends on the claim. Break-in through a non-compliant door may result in reduced or denied claims. Unrelated claims (fire, flood) typically unaffected. Compliance is safest.
How do I prove my locks are compliant?
BS3621 locks have the certification mark on the faceplate. Keep fitting receipts if locks were recently installed. A locksmith can provide a compliance statement if needed.
Are anti-snap cylinders an insurance requirement?
Not typically specified by name, but some policies require TS007 or "approved" cylinders. Anti-snap (TS007 3-star) exceeds most requirements. Check your specific policy.
Do windows also have insurance lock requirements?
Many policies require key-operated window locks, especially on ground floor and accessible windows. Requirements are usually less specific than door lock standards.
What if I can't fit BS3621 locks (listed building, unusual door)?
Discuss with your insurer before a claim situation. They may accept equivalent security or endorse your policy with alternative requirements. Document the constraint.
How much does it cost to make my locks insurance-compliant?
A BS3621 mortice lock fitted typically costs £80-180 depending on complexity. Often cheaper than the premium increases or claim reductions from non-compliance.
Should I inform my insurer after upgrading my locks?
Not mandatory for standard upgrades, but informing them documents your compliance and may occasionally reduce premiums. Keep fitting receipts regardless.
Taking Action
Immediate Steps
- Find your policy documents
- Locate security conditions section
- Audit your current locks against requirements
- Address any gaps before they matter
If Upgrading
- Get locksmith quote for compliant locks
- Confirm BS3621 certification will be fitted
- Keep all documentation after work
- Consider informing insurer of improvements
The Bottom Line
Lock compliance isn’t optional—it’s a condition of your coverage. The upgrade cost is minimal compared to claim values. Protect your insurance protection by meeting the requirements you agreed to when you bought the policy. See our choosing the right lock guide for recommendations.