Should You Change the Locks When You Move Into a New House?
Yes. Change or rekey the locks on the day you move in. You have no way of knowing how many keys exist for a second hand house because previous owners, builders, cleaners, dog walkers and estate agents all held them at some point and nobody keeps a record.
The short answer
- Assume unknown keys exist because the seller cannot account for every copy
- Prioritise the front door the back door and any patio door
- A euro cylinder swap costs £15 to £40 per door and takes ten minutes
- Check the lock meets BS3621 or your insurer may not pay out
- Rented homes are the landlord's decision so ask before changing anything
Why it matters more than people think
Most home insurance policies exclude theft where there is no sign of forced entry. If someone enters with a key that was never returned the claim can be refused, so the cost of a new cylinder is small against that risk.
There is also a simple practical reason. Older properties often have a mix of worn locks and half working handles and moving day is the one time the house is empty and easy to work on.
Which locks to deal with first
Work through them in this order and the whole job is usually done in an afternoon.
- Front door cylinder and any deadlock
- Back door and side gate
- Patio and French doors
- Garage and any outbuilding
- Window locks especially on the ground floor
- Smart locks and keypad codes which need factory resetting
- Key safes left by carers or holiday lets
- Alarm codes and any app based access
Change the lock or just the cylinder
On a modern uPVC or composite door you almost never replace the whole lock. You swap the euro cylinder which is a single screw behind the latch and costs very little.
On an older wooden door with a mortice lock a full replacement is more likely and this is where a locksmith earns their fee.
| Job | DIY cost | Locksmith cost |
|---|---|---|
| Euro cylinder swap | £15 to £40 | £70 to £120 |
| Anti snap cylinder upgrade | £25 to £60 | £90 to £150 |
| Mortice lock replacement | £25 to £70 | £100 to £180 |
| Rekeying an existing lock | Not practical | £60 to £120 |
| Whole house four doors | £80 to £200 | £250 to £450 |
What to buy
For a front door choose an anti snap anti bump anti drill cylinder to TS007 three star or a Sold Secure Diamond rating. For mortice locks look for BS3621 which is the standard most UK insurers name in their policy wording.
Measuring a euro cylinder matters. Measure from the centre screw hole to each face separately because most are not symmetrical and a cylinder that protrudes more than a few millimetres is easier to snap.
Renting rather than buying
If you are a tenant the locks belong to the landlord. Ask in writing whether the locks were changed after the last tenancy and request it if not. Do not change them yourself without permission because the landlord must keep a means of emergency access.
While you are at it
Moving day is the natural time for the rest of the security basics. Change any alarm code, reset a video doorbell to your own account, check the smoke and carbon monoxide alarms and note where the stopcock and consumer unit are.
Frequently asked questions
Do I legally have to change the locks when I buy a house?
No it is not a legal requirement but it is standard advice and some insurers ask about lock standards when you take out a policy.
How much does it cost to change the locks on a house?
Around £80 to £200 doing it yourself across four doors or £250 to £450 using a locksmith.
Can I change a uPVC door lock myself?
Usually yes. Measure the euro cylinder from the centre screw to each face, buy the matching size and swap it with one screw.
What lock standard do insurers want?
Most UK policies name BS3621 for mortice locks and many now prefer TS007 three star or Sold Secure Diamond cylinders on front doors.
Planning a move?
BlueSky Removals gives fixed written prices after a free video or home survey. Call 0800 090 3125 or request a quote online.