Call any time
Mortice Lock Replacement Oxford 5 Lever BS3621 Locks
BS3621 kitemarked 5 lever deadlocks and sashlocks fitted to timber doors across Oxford, matched to your existing 2.5 or 3 inch case so the door is not butchered.
Get a mortice lock price
Tell us what you need and we will call you straight back. Calling is quickest: 07520 644 595. Photos by WhatsApp: 07466 695655
BS3621 kitemarked locks
The 5 lever standard most home insurers name for final exit doors.
Case size matched
2.5 inch or 3 inch bodies measured so the new lock drops into the old pocket.
Deadlock or sashlock
Key-only bolt for front doors, latch plus bolt for back and kitchen doors.
Fitting £85 to £115
Lock £35 to £65 on top. Price fixed on the phone before we leave North Oxford.
Our mortice lock replacement service in Oxford fits British Standard BS3621 5 lever deadlocks and sashlocks to wooden doors, usually within 10 to 30 minutes of your call inside the city, from £85 plus the lock. We measure the existing case so the replacement sits in the same pocket, check the keep in the frame, and hand over keys and an itemised invoice your insurer will accept.
If you have only lost a key and the lock itself is sound, re-levering it is usually cheaper than a new lock. Everything else on this page explains how to tell what you have and what your policy expects.
What does BS3621 actually mean on a mortice lock?
BS3621 is the British Standard for thief resistant locks operated by a key from both sides. A lock only carries the number if it has passed tests against drilling, sawing, picking and forcing the bolt back. In practice that means at least five levers, a bolt that throws a full 20mm into the frame, and hardened steel plates or rollers inside the case where a drill or hacksaw would be aimed.
The 5 lever count matters because each lever is a separate gate the key must lift to exactly the right height. A 2 or 3 lever lock, still common on Edwardian back doors in Headington and East Oxford, has far fewer key combinations and none of the anti-drill protection. It may work perfectly and still fail an insurer’s checklist.
Two related standards are worth knowing. BS8621 locks open from inside with a thumb turn and no key, which suits flats and shared houses where people must be able to get out in a fire. PAS 3621 locks need a key on both sides but are tested the same way. If you rent out rooms, ask us which one your exit route needs before you buy anything.
How to read your faceplate before you call
Open the door and look at the narrow metal plate on its edge where the bolt comes out. Everything you need to know is usually stamped there.
- Look for the kitemark. A small heart-shaped symbol followed by BS3621 (often with the year, such as 2007 or 2017) confirms the standard.
- Count the levers. Most makers print 5 LEVER or 5L. If it says 3L or nothing at all, assume it is below standard.
- Note the brand and model. ERA, Union, Yale and Chubb stamps help us bring the right replacement first time.
- Measure the plate. Roughly 155mm tall usually means a 2.5 inch case. Close to 175mm usually means 3 inch. A photo with a tape measure next to it is ideal.
- Check for a handle. A lever handle on the same plate tells us it is a sashlock rather than a deadlock.
Send the photo by WhatsApp to 07466 695655 and we can confirm the exact part and fixed price before travelling.
Sashlock or deadlock: which mortice lock does your door need?
Mortice deadlock
A single bolt thrown and withdrawn only by the key. No handle, no latch. It sits about a third of the way up a front door, normally below a nightlatch, so the door can be pulled shut on the latch and double locked when you leave.
Best for: front doors that already have a rim latch.
Mortice sashlock
Two bolts in one case. A sprung latch held by lever handles keeps the door closed, and the key throws a separate deadbolt. The spindle hole is 8mm and handle centres are usually 57mm, so existing handles often refit.
Best for: back, side and kitchen doors with no other lock.
Swapping one type for the other on the same door is possible, but it means new holes for a spindle or filling old ones. Like for like is quicker and cheaper, so we always try that first.
2.5 inch vs 3 inch case sizes and why they matter
Mortice locks come in two common case depths. A 2.5 inch (64mm) case puts the keyhole about 44mm in from the door edge. A 3 inch (76mm) case puts it about 57mm in. Fit the wrong one and either the keyhole misses the existing escutcheon or the case will not go deep enough into the pocket.
Older Oxford doors throw up a few quirks. Panelled Victorian front doors in Jericho and Summertown sometimes have a narrow stile where only a 2.5 inch case fits without weakening the timber. Some 1930s doors in Cowley and Botley have a 3 inch pocket cut for an older, chunkier lock. Where the new body is slightly larger, we extend the recess with a chisel and router rather than forcing it, and we fill and tidy any redundant keyhole on the face.
The frame matters as much as the lock. A BS3621 bolt is only as strong as the keep it shoots into, so we check that the box keep is deep enough and screwed into solid timber, not just the soft architrave.
Insurer requirements for mortice locks on final exit doors
Many UK home policies say that final exit doors must be secured by a 5 lever mortice deadlock conforming to BS3621, or by a multipoint locking system on uPVC and composite doors. Wording differs between insurers, so read your schedule rather than assume.
Check this before a claim, not after
If a burglar gets in through a door that did not meet the stated standard, some insurers reduce or refuse the payout. A kitemarked lock and an itemised invoice showing the date and model fitted is the simplest evidence you can keep.
A final exit door is the one you leave by and lock from outside. Internal doors, and back doors that are only bolted from inside, are usually treated differently. Timber French doors and patio doors have their own rules, which we cover on our patio and French door lock page, and extra bolts top and bottom are explained under security bolts for timber doors.
Replace, repair or rekey your mortice lock?
| Situation | Usual answer | Typical cost |
|---|---|---|
| Key lost, lock is BS3621 and works well | Re-lever to a new key | £45 to £65 per lock |
| Key stiff or bolt catching on the keep | Clean, lubricate and realign | £45 to £75 |
| Lock jammed, door stuck shut | Repair, no fix no fee | £55 to £85 |
| 3 lever lock or no kitemark | New BS3621 lock | £85 to £115 plus lock |
| Bolt broken or case cracked after forcing | New lock and make safe | Quoted after a photo |
Re-levering keeps the case in the door and swaps the internal levers so old keys stop working; there is more on that on our lock rekey page. If the lock is jammed and the door has dropped, our no fix, no fee lock repair service handles that side of things.
What happens when we replace a mortice lock
We set off from Woodstock Road in North Oxford once the price is agreed. A like-for-like swap normally takes 30 to 45 minutes: old lock out, recess cleaned, new case in, keep checked, and every key tested from both sides with the door open and closed. If the keep needs moving or the pocket needs enlarging, allow a little longer.
You get three or more keys with the new lock and an invoice listing the make, model and standard. Prices include VAT and labour, with the lock listed separately. If you are also changing the cylinder on a uPVC back door or adding a latch to the front, we can do it on the same visit; see the full door lock change service or the wider list of locksmith services in Oxford.
Moving into a house with an unknown key history is a good reason to replace or re-lever every mortice lock at once. Our home security checklist for Oxford houses walks through the rest of the doors and windows.
Mortice lock replacement prices in Oxford
Prices include VAT and labour, with the lock itself listed separately and agreed before we travel.
| Service | Price | What's included |
|---|---|---|
| Mortice deadlock or sashlock fitting (BS3621 5 lever) | £85 to £115 + lock £35 to £65 | Case size matched, keep checked, 3 keys |
| Lock rekey (re-levering) | £45 to £65 per lock | Same lock body, new keys |
| Key won’t turn (clean, lubricate, align) | £45 to £75 | Stiff key or bolt catching |
| Lock repair | £55 to £85 | No fix, no fee |
| Extra keys | £8 to £25 per key | Cut on the visit where possible |
Prices include VAT and labour. Parts are listed separately. See the full Oxford locksmith price list.
