24/7 · CB1 · DBS checked engineers
Cambridge Lock Installation
Our Cambridge engineers handle lock installation across Cambridge and the surrounding Cambridgeshire area. Available 24/7, any day of the year; 28-minute average arrival. No surprises on price.
Other locksmith services in Cambridge need lock changes, repairs, upgrades or commercial help instead?
All services in Cambridge →Converted multi-occupancy houses often contain several generations of doors under one roof: an original timber front door, internal partition doors of varying leaf thickness, and fire-rated corridor doors on newer conversions. Each type has different fitting requirements — mortice dimensions on the timber front door, consistent backsets on the internal room doors, and intumescent-seal clearance on fire doors. We identify each door type on arrival before specifying any cylinder, so the quote matches the actual access-point inventory.
On arrival
Measurement checklist: what we record on arrival
Four measurements are taken before any hardware comes off the van on a Cambridge installation. A wrong-part revisit costs more than two minutes of careful measuring — we never skip this step.
| Measurement | Why it matters | Typical range |
|---|---|---|
| Stile width | Sets which internal door cylinder case will physically fit without weakening the door at the lock rail. Internal HMO room doors are typically lighter than front doors and run a smaller cylinder — measure the leaf thickness per door, not per property. | 44 mm minimum for a full BS3621 mortice; narrower stiles may require a slimline case or a euro-cylinder alternative |
| Frame recess depth | HMO multi-room installation: measure door leaf thickness and backset per room door — internal doors typically run 30/30 or 35/35 cylinders, smaller than the front door. Check cam engagement under load on each door before handing back keys. | 13–20 mm on most residential timber; composite and UPVC frames can run shallower |
| Door thickness | Controls the cylinder length from face to face. A cylinder sitting proud of the outer face — even by 3 mm — creates a snap-attack leverage point that defeats anti-snap ratings. | 44 mm (standard timber), 54 mm (solid composite), 70 mm (hardwood or fire-rated) |
| Cut-out position | The distance from the door edge to the centre of the existing cut-out sets the backset. Extending an existing cut-out adds time and cost; fitting into the existing position is preferred wherever the hardware allows it. | 45 mm backset (most residential); 60–70 mm on commercial and period doors |
All four measurements are recorded on the job card and referenced in the installation certificate. If the measurements reveal a door that cannot accept the specified hardware without prep work, that is flagged and quoted before any tools come out.
Before quoting
Six door conditions that change the Cambridge quote
Fire-door compliance adds a line to the HMO installation quote that a domestic-only install wouldn't carry: intumescent drop seals, approved closers, and the hardware grade the licence inspection requires. These are costed separately and confirmed from the licence conditions before work begins — so the installation price is fixed, not approximate. From £59 for a standard installation on a door in good condition.
- 01 Narrow stile
Period terrace stile geometry varies by door age and previous repairhistory. Where an earlier mortice installation has been filled and re-cut,the residual timber at the lock rail may be below 44 mm effective width.Survey confirms the available stile before hardware is specified.
- 02 Composite vs timber construction
Composite and UPVC doors use a different cylinder system from timber — euro profile with a multipoint gearbox rather than a mortice. Cylinder cam engagement on internal doors must be checked under load; light door construction means the cam can move under repeated key use if the cylinder is oversized. Confirming construction type before ordering avoids a wrong-part visit.
- 03 Existing cut-out dimensions
HMO internal door cut-outs vary room by room depending on when each door was converted. A recent conversion may have a standard cylinder cut-out; an original door may have only a latch-only aperture. We check each door individually before confirming hardware — inconsistent cut-outs on a multi-room visit change the per-door time estimate.
- 04 Nightlatch position
Internal room doors in converted HMO buildings are sometimes thinner than a standard external door, and a full-depth nightlatch case may protrude past the inner face. Case depth is checked against door thickness at each room; a narrower-profile case is substituted where protrusion would prevent the door from closing cleanly against the frame.
- 05 Frame condition
We measure the internal door leaf the frame for squareness, settlement, and rebate wear before committing hardware to final position. A frame that is out of square or has a worn rebate needs addressing first — fitting a mortice into a moving frame produces a bolt that binds within months.
- 06 Letterbox clearance
On shared-occupancy properties the communal entrance letter plate position affects where the primary cylinder can be mounted on the main door. Where the communal plate is centrally positioned, the lock is mounted above it at a height that maintains both letter plate access for post and cylinder accessibility for occupants. Internal room doors without letter plates are not subject to this clearance constraint and follow the standard mid-stile cylinder height.
Specification
Hardware compatibility: will this door accept BS3621?
Three questions answer most hardware compatibility conversations on a Cambridge installation. We work through each on arrival and confirm the spec before any cutting or drilling starts.
- 01
Can this door accept BS3621?
A BS3621 5-lever mortice requires a minimum stile width (44 mm), a frame rebate to accept the forend, and sufficient door thickness at the lock rail. We check all three before specifying — a door that cannot take a BS3621 case without structural compromise will be quoted with a compliant alternative using a internal door cylinder or cylinder cam engagement instead.
On a multi-room property, test each cylinder independently before signing off — a cylinder that passes open-door test may bind on the closed door under frame pressure.
- 02
Cylinder size: 35/35 vs bespoke
Standard residential doors run 35/35 or 35/45 euro cylinders; composite and commercial doors often need bespoke lengths. We confirm the cam engagement the cylinder run on site — face to face across the door leaf at the lock rail — and confirm the access point count specification before fitting. An oversized cylinder leaves the anti-snap collar exposed.
Anti-snap cylinders must be sized with the break-point inside the door face. A cylinder that is even 3 mm too long on the outside is vulnerable to a snap attack regardless of its anti-snap rating.
- 03
Nightlatch: rim vs mortice
Rim nightlatches surface-mount on the door face and require backplate clearance from the door edge and from any adjacent furniture. Mortice nightlatches fit into the door thickness and suit doors where the face is already occupied by a letterbox or knocker. The choice depends on the stile geometry confirmed at measurement, not a preference.
On insurance-graded installs both the primary lock and the nightlatch are noted on the compliance certificate. If the policy specifically names a rim nightlatch at a given standard, we confirm that against the door construction before the certificate is issued.
Completion
Handover and testing
The installation is not complete until every lock has passed a full function test on a closed door. On Cambridge jobs we sign off three checks before handing back keys.
- Cycle test
Where an HMO door schedule covers more than six rooms, cycle testing is carried out floor by floor and results are logged per room rather than as a single pass/fail for the property. This per-room log allows any door that develops a fault after handover to be traced to its installation date and technician.
- Key issue
Keys are counted against the job card in front of the keyholder. Each key is labelled with the door reference it was cut for. No key leaves site unaccounted — if the agreed number is not present at handover, the job card flags the discrepancy before the engineer leaves.
- Written summary and certificate
For multi-occupancy properties the written summary serves as the baseline key register: each room door listed with its cylinder serial and the keys issued per occupant, signed off at handover. The landlord copy is handed over at job end; a duplicate is available for the letting agent's compliance file. Restricted keyway scheme documentation records the keyway reference for future changeover orders, preventing a wrong-profile cylinder order at the next tenancy transition.
Questions
Lock installation FAQ: Cambridge
On multi-let properties the primary installation brief is managing individual access independently — each room on its own cylinder, the common areas on a separate scheme, so a departing tenant only triggers a rekey on their specific door.
- Do I need to measure my door before calling?
- No — we measure on arrival. It helps to know whether the door has alreadyhad a mortice fitted: period terrace doors often have an older case that thenew hardware will replace, and the existing cut-out dimensions affect theprice. If you have access to the door age or previous locksmith records thatis useful, but not required.
- Will the new lock look different from the original?
- On like-for-like replacements — same case position, same forend size — the external appearance changes only in terms of the new cylinder rose or escutcheon. On period doors where the original furniture is being retained, the escutcheon fit is checked for compatibility before the hardware is sourced. Where the new spec requires a different door face profile (e.g. switching from a mortice keyhole to a euro cylinder profile), we flag that on the booking call before the job date.
- How long does a Cambridge lock installation take?
- A standard like-for-like cylinder replacement on a composite or UPVC door takes around 30–45 minutes including the full test cycle. A new BS3621 mortice installation on a timber door — where the existing cut-out is the right size — takes 60–90 minutes. If the door needs prep before the hardware fits (rebate adjustment, aperture extension, hinge correction) we agree the additional time and cost before starting. We do not proceed past the assessment stage without a confirmed price.
- What if the door needs repair work before the lock can be fitted?
- The most common pre-fit repair on HMO room doors is a door that has been repainted so many times that it binds in the frame when closed. We assess the clearance before any lock hardware goes in: a door that binds under normal pressure will bind worse after the lock is fitted. A quick door-edge trim solves this in most cases; where the door-to-frame geometry needs a joiner's attention, we note it and schedule the lock fit separately.
Lock Installation in Cambridge — FAQ
Common questions about lock installation in Cambridge.
Can you install a lock on a brand-new door?
On multi-let properties the primary installation brief is managing individual access independently — each room on its own cylinder, the common areas on a separate scheme, so a departing tenant only triggers a rekey on their specific door. Yes — this is one of our most common installation jobs in Cambridge. Carpenters and joiners often hang the door and leave lock fitting to specialists. We measure the rebate, chisel for a BS3621 mortice case, fit the strike plate, and test through a full key cycle. Finished work looks factory-fit.
Can you keyed-alike multiple new locks?
Yes — if you want one key to open your front and rear doors, we supply keyed-alike cylinders on the most common profiles. Arrange at the survey stage so we bring matching parts. This works cleanly on UPVC euro cylinders and on certain mortice profiles.
Do you install locks on gates and outbuildings?
Yes — weather-rated padlocks, BS-grade hasps, garden gate locks, and shed/garage door hardware are all regular installation work across Cambridge. We match the lock to the exposure (weatherproofing matters outdoors) and fit on the same visit.
Will a new lock invalidate my door warranty?
Not normally. Most door manufacturers specify that lock installations must be done by a competent locksmith — we are, and we fit to manufacturer-approved positions and dimensions. If in doubt, mention the door brand when you call and we'll confirm compatibility before attending.
Also nearby
Areas near Cambridge
we also cover
Our engineers don't just cover Cambridge — we serve the surrounding towns and neighbourhoods too. If you're just outside Cambridge, we can still reach you fast.
- Ely 15.2 mi
- Huntingdon 16.5 mi
- St Neots 18.8 mi
- Royston 14.2 mi
- Newmarket 13.5 mi
- Bury St Edmunds 25.2 mi
- Peterborough 29.4 mi
Ready when you are
Need lock installation in Cambridge now?
24/7 dispatch across Cambridge and the CB1 area. Fixed quote before work starts. Free call-out with every completed job.