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Lock Installation in Bath
Lock Installation throughout Bath, around the clock, seven days a week — average response 25 minutes. Free call-out with every job — fixed price agreed before any work starts.
Other locksmith services in Bath need lock changes, repairs, upgrades or commercial help instead?
All services in Bath →Bath stone and lime-mortar frame construction requires a different fixing approach than brick: the stone is softer than most visitors expect and fixings driven into unsound lime mortar joints will pull free under bolt load. We use resin anchors or larger-gauge fixing screws into sound stone rather than relying on the standard timber-screw approach used on brick-frame or timber-frame properties.
On arrival
Measurement checklist: what we record on arrival
Four measurements are taken before any hardware comes off the van on a Bath 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 imperial case dimension case will physically fit without weakening the door at the lock rail. Georgian and Regency Bath apertures sized before 1850 use imperial proportions that do not correspond to any standard metric case — measure in both systems before ordering. | 44 mm minimum for a full BS3621 mortice; narrower stiles may require a slimline case or a euro-cylinder alternative |
| Frame recess depth | Imperial aperture measurement: record aperture height and depth in both inches and millimetres. Compare against the metric BS3621 replacement case body. If no direct fit exists, source a pre-metric case from a heritage hardware supplier. Both measurement systems recorded on job card. | 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 Bath quote
Reading Victorian terrace stock close to the town centre is often in HMO orconverted tenure, where the landlord's insurer may require a higher BS3621grade than the existing installation carries. The compliance gap isidentified on arrival and the upgrade cost confirmed before any hardware ischanged. From £59 for a standard installation on a door in good condition.
- 01 Narrow stile
Canterbury pilaster-style doorways present a non-standard stile width where the decorative pilaster column overlaps the outer face of the door stile. The pilaster reduces the visible stile face but not the actual timber depth available for the case body. Case depth is measured from the true stile face behind the pilaster, and the forend is selected to sit flush with the door face rather than the pilaster face.
- 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. Imperial forend recess in an early Bath door may be narrower than a standard 20 mm metric forend — confirm the recess width before ordering a metric replacement. Confirming construction type before ordering avoids a wrong-part visit.
- 03 Existing cut-out dimensions
Great Yarmouth seafront terrace: marine moisture causes the door leaf to cup outward at the mid-rail from prolonged salt-air exposure. The backset measurement is taken at the door face rather than at the cupped mid-point, which would give a shorter reading and lead to an under-specified case backset. Both the face dimension and the cup depth are recorded on the job card so the case is ordered to the face measurement and the keep position accounts for the cupped leaf under normal closing pressure.
- 04 Nightlatch position
Ipswich and Norwich flint-framed terrace properties treat the stone/flintjamb as a fixed surface for the nightlatch keep. The keep recess is cutinto sound brick rather than flint where possible; where flint occupies thekeep zone, resin anchor fixings are used to seat the keep securely.
- 05 Frame condition
We measure Bath aperture in both imperial and metric 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
Ipswich and Norwich terrace properties with flint in the frame constructiontreat the letterplate position as fixed where it is already cut through theflint face: re-cutting a flint aperture is specialist work. Where theexisting aperture is adequate, the plate is retained or directly replaced.
Specification
Hardware compatibility: will this door accept BS3621?
Three questions answer most hardware compatibility conversations on a Bath 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 imperial case dimension or pre-metric Bath aperture instead.
Pre-metric case sourcing: Chubb and Union produce BS3621-compliant cases in imperial body dimensions for heritage applications.
- 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 Georgian case proportion against replacement case the cylinder run on site — face to face across the door leaf at the lock rail — and confirm the Georgian case proportion 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 Bath jobs we sign off three checks before handing back keys.
- Cycle test
Cardiff terrace properties with lime mortar keep fixings are cycle-testedwith a load check specifically on the keep after the sequence: lime mortaris softer than cement pointing and the keep pull-out resistance isconfirmed through the cycle test load, not assumed from the fixing depth.
- 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
Great Yarmouth seafront holiday-let terrace: the summary notes the marine-environment hardware specification — stainless or marine-grade cylinder and keep fixings — and includes a written recommendation for annual cylinder inspection. Salt air accelerates corrosion inside the cylinder body, which is not visible from outside the door. The maintenance note advises the owner to have the cylinder removed and inspected each year and to replace it at the first sign of stiffness in the key turn.
Questions
Lock installation FAQ: Bath
Reading HMO and converted tenure terrace properties may require a higherBS3621 grade than the existing installation to meet the landlord's policyconditions. The compliance requirement is identified at survey, and theupgrade scope is confirmed before any hardware is changed — not revisedafter the job starts.
- Do I need to measure my door before calling?
- No — we confirm all measurements on arrival. For southern coastal propertieslike Portsmouth, knowing whether marine exposure has caused timber swellingis useful background: we bring different gauge-setting tools for doors thatare known to be affected. The full measurement is taken on site before anywork begins.
- 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 Bath 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?
- Oxford conservation-area terrace mortice cases are assessed for repaircompatibility with the period hardware style: where the case is visiblethrough the escutcheon, a period-appropriate case replacement is preferredto a modern equivalent that conflicts with the conservation character ofthe door.
Lock Installation in Bath — FAQ
Common questions about lock installation in Bath.
Can you install a lock on a brand-new door?
Reading HMO and converted tenure terrace properties may require a higherBS3621 grade than the existing installation to meet the landlord's policyconditions. The compliance requirement is identified at survey, and theupgrade scope is confirmed before any hardware is changed — not revisedafter the job starts. Yes — this is one of our most common installation jobs in Bath. 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.
Do I need BS3621 on a new installation?
For external doors on Bath homes with standard insurance — yes, almost certainly. BS3621 is the minimum most UK home insurers specify on final-exit wooden doors. We fit BS3621 as standard and issue written paperwork confirming the standard for your insurance file.
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.
We've just moved into a new-build in Bath — do the locks already meet insurance standards?
Not always. Many Bath new-builds come with entry-level euro cylinders on UPVC or composite doors that lack the TS007 3-star anti-snap rating, and sometimes a mortice case that predates BS3621 on the side door. We survey the whole property, identify any hardware gaps, and upgrade to compliant standards on the same visit — with a compliance pack for your insurer.
Also nearby
Areas near Bath
we also cover
Our engineers don't just cover Bath — we serve the surrounding towns and neighbourhoods too. If you're just outside Bath, we can still reach you fast.
- Bristol 12.4 mi
- Frome 13.1 mi
- Chippenham 12.8 mi
- Trowbridge 11.6 mi
- Keynsham 5.9 mi
Ready when you are
Need lock installation in Bath now?
24/7 dispatch across Bath and the BA1 area. Fixed quote before work starts. Free call-out with every completed job.