You Do Not Know Who Has a Key to Your New Home
The previous owner of your new home may have been meticulous about retrieving every key from every person they gave one to. They may also have given keys to contractors, cleaners, house-sitters, neighbours, family members, and estate agents — and retrieved none of them. They may not even remember everyone who had a key. The estate agent had a key for viewings. The solicitors may have held a key. Builders, plumbers, or electricians who worked on the property while it was on the market may have been given temporary access and never asked to return it.
You cannot audit this history. The only way to know for certain that no unauthorised copy of your key is in circulation is to change the locks.
How Many Copies of a Key Typically Exist
A typical three-bedroom house that has changed hands a few times and had occasional tradespeople over a decade will conservatively have had four to eight keys cut from the original — and each of those can be used as a source for further copies. Many modern Euro cylinders and mortice locks use unrestricted keyways (the profile of the key blank) that can be copied at any high street key-cutting kiosk without identification or authorisation. The key you are handed on completion day may itself be a fifth-generation copy.
"A locksmith can change locks when you move into a new home. This is one of the most commonly requested services and one of the most worthwhile — you have no way of knowing how many copies of the previous occupant's keys exist."— Master Locksmiths Association, What Can a Locksmith Do?
What a Complete Lock Change Involves
A typical three-bedroom house lock change covers: the front door (one or two locks, depending on whether there is a Yale-type nightlatch and a mortice lock), the back door, and any side access doors. If there is an integral garage, the door between the garage and the house should also be assessed — it is often an interior door that has never been fitted with a proper external-specification lock.
The locksmith will assess each door, confirm what lock type is currently fitted, and discuss whether you want like-for-like replacement or an upgrade. Moving house is the natural moment to upgrade to:
- TS007 3-star anti-snap cylinders on UPVC and composite doors
- BS 3621 five-lever mortice locks on timber doors
- Sold Secure Gold padlocks on garage side doors and gates
Insurance Requirements
Most home insurance policies require specific lock standards — BS 3621 for timber doors, TS007 3-star for UPVC — and many policies include a clause requiring locks to be changed when keys are lost or when there has been unauthorised access. Moving house technically represents a situation where the history of key copies is unknown. Some insurers will specify this in their policy terms; others leave it implied.
"Check whether your door locks meet BS3621 — a British Standards Institute standard for locks tested against burglary methods. Look for the British Standard Kitemark engraved on the lock. These locks are often called 'Insurance Approved Locks.'"— Neighbourhood Watch / Our Watch, Key Home Protection
When to Do It
The ideal time is on moving day or within the first few days of occupation, before you have settled into the property. Prioritise the front door first, then the back door. If contractors are coming in and out during early renovation work, consider fitting temporary cylinders (rekeyed after works complete) so that tradespeople have access during the day without having long-term access to your key.
Restricted keyway cylinders — cylinders where the key can only be copied at a specific locksmith with your authorisation — are worth considering if you have had a history of key management problems or manage a rental property. They add a modest premium to the cylinder cost but eliminate the risk of unauthorised key copying entirely.
Get Quotes for a New-Home Lock Change
A complete lock change with anti-snap cylinders on a three-bedroom house is straightforward work for a local locksmith.
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