Door Lock Fitting
Fitting a lock is carpentry that happens to involve a lock
Swapping a lock for another of the same size is a mechanical job. Putting a lock into a door that has never had one is a different discipline, and it is where most of the bad work we are called to repair comes from. The mortice has to be cut in the middle of the stile, square and to depth, without weakening the timber. The keep has to be positioned so the bolt enters cleanly rather than being nudged in by force. The face plate has to sit flush. None of that is difficult with the right tools and a steady approach, and all of it is very difficult to undo once it has gone wrong.
That is why we treat fitting as its own service rather than a smaller version of replacement. A door that has been cut badly does not just look poor. An oversized mortice leaves a stile too thin to resist a shoulder, a keep screwed into the stop rather than the frame pulls out on the first serious attempt, and a lock fitted a few millimetres out of square will bind every winter when the door swells. The hardware in those cases is perfectly good and the door is still not secure.
The commonest reasons people call us are simple ones. A front door with only a nightlatch that needs a deadlock to satisfy an insurer. A back door or side gate that has never had anything better than a bolt. A newly hung door from a builder who fitted the hinges and left the locks to someone else. A flat that needs a second point of security without changing what is already there.
How We Fit a Lock From Scratch
A lock is only as good as the timber around it and the keep it throws into. Most of the work in fitting one is in those two things rather than in the lock itself.
Adding a Second Lock to a Front Door
A great many North London front doors carry a rim nightlatch and nothing else, which means the door is held by a spring latch and can be opened by anyone inside without a key. Most home insurance wording expects a deadlock as well, keyed from both sides on a timber door. Fitting one means cutting a mortice below the existing latch, matched to the door thickness and stile width so nothing is weakened, and positioning the keep so the bolt throws its full length.
Meeting the Insurance StandardCutting a New Mortice Properly
The mortice is cut central to the stile, to a depth that takes the case without breaking through, and square in both planes so the lock is not fighting the timber from day one. The face plate is let in flush, the spindle and keyhole are drilled from both sides so nothing tears out, and the keep is chiselled into the frame rather than surface-screwed. On a period door with panels and mouldings, the position also has to respect what the door can carry structurally.
If a Lock Has Failed InsteadThe Small Hardware That Does the Work
Hinge bolts stop a door being levered off its hinge side. Sash jammers hold a uPVC door against a kick. Door viewers and restrictor chains let you open to a stranger without opening at all. A letterbox guard stops a hand or a rod reaching the latch. Individually these are small items, and together they usually add more real security to a flat door than a more expensive cylinder does, particularly where the lock itself is already sound.
One Key Across Every DoorWhy the Timber Matters as Much as the Lock
- Cut square, cut central, cut once — the mortice is marked from the door rather than from a template, because no two period doors have the same stile.
- Keeps let into the frame, not screwed to the stop — a keep sitting on the surface is the part that gives way first, however good the lock is.
- We say when a door cannot take it — a thin, hollow or badly split door will not hold a deadlock, and fitting one anyway would only look secure.
- 180-day warranty on locks, lifetime on keys — on the hardware we supply and on the fitting itself, itemised on the invoice.
Our Process - What Happens When You Call
- Tell us what the door is. Timber, uPVC, composite or a flat entrance door, and roughly how old. Thickness and stile width decide what can be fitted before anything else does.
- Say what you want it to do. Satisfy an insurer, stop a door being levered, let you answer safely to a stranger, or simply put a working lock on a door that has never had one.
- Recommendation, then a price. We tell you what suits the door and the purpose, including where a cheaper piece of hardware genuinely does the job better than an expensive one.
- Fitted, adjusted and left clean. Cut, fitted, keeps aligned, the door tested repeatedly from both sides, and the shavings taken away rather than left on your carpet.
Why Choose N1 Locksmiths?
You speak to the person doing the job
Describe the door once, to the engineer who will cut it, so the right cases, keeps and blanks are on the van before it leaves Holloway Road.
Priced on the call, before we travel
Fitting a deadlock, adding hinge bolts and hanging security hardware on a flat door are different jobs, and you hear the price for each up front.
Cut by hand where a machine would damage it
Period doors with mouldings and panels are marked and cut by hand rather than routed, because a router does not know where the panel starts.
180-day warranty on locks, lifetime on keys
The hardware and the fitting are both guaranteed, and the invoice names the exact products used.
Honest about what a door can carry
If the timber is too thin or too far gone to hold what you have asked for, we will tell you before we cut rather than after.
15–30 minutes across N and NW
Worked from Holloway Road, so a fitting job is usually booked for a time that suits you rather than a fortnight away.
Send a photograph of the door and the frame
Fitting jobs are the easiest to price accurately in advance, because everything depends on what is already there. A picture of the face of the door, one of the edge where the lock will go, and one of the frame alongside it tells us the thickness, the stile width, what is fitted now and whether the door hangs squarely. From those three photographs we can normally recommend what suits the door and give you a firm price before anybody travels, typically reaching you within 15–30 minutes across the N and NW postcodes.
Message on WhatsAppCALL 020 7129 7496Explore Our Locksmith Services
Fitting hardware to one door usually starts a conversation about the others. These are the jobs most often booked in the same visit — a tired mechanism sorted before new hardware goes near it, a uPVC back door given the protection timber cannot take, or every new lock brought onto a single key.
Areas We Cover Across London
We fit locks across N1 to N22 and NW1 to NW11 from 37 Holloway Road in N7, and this is the service where the housing stock decides almost everything. The conservation streets through Canonbury, Highbury, Barnsbury and Hampstead are full of original panelled doors with narrow stiles and a century of paint, where the answer is careful hand cutting and often a smaller lock than the customer first asked for. The converted flats around Holloway, Archway and Kentish Town are usually communal-entrance buildings where the flat door itself carries the security, so viewers, restrictors, hinge bolts and letterbox guards do more good than a heavier deadlock. Newer stock towards Finchley and Golders Green is mostly uPVC and composite, where nothing is cut at all and the work is upgraded handles, jammers and restrictors.
FAQs – Door Lock Fitting
My front door only has a Yale latch. Do I need a second lock?
Most home insurance wording expects a deadlock in addition to a nightlatch on a timber front door, so it is worth checking your policy. Beyond the paperwork there is a practical reason: a nightlatch is a spring latch, which means it holds the door rather than locks it, and it can be opened from inside without a key by anyone who has got in another way.
Can you fit a lock to a door that has never had one?
Yes, and that is what this service is for. It means cutting a new mortice, drilling for the key and spindle, letting in the face plate and cutting a keep into the frame. The thing we check first is whether the door can take it — stile width and thickness decide which lock is appropriate, and a door too thin for a deadlock is better served by different hardware.
Will fitting a lock damage or weaken my door?
Cut correctly, no. Cut badly, considerably. The mortice removes timber from the middle of the stile, so it has to be central, no deeper than the case needs and no wider than the lock body. Where a door is narrow, already split, or a hollow-core internal door, we will say that a deadlock is the wrong choice rather than cutting it and hoping.
What can be fitted to a uPVC or composite door?
Different hardware entirely, because there is no timber to cut. Those doors already carry a multipoint mechanism, so the additions that make a real difference are sash jammers, upgraded handles with cylinder protection, restrictors and door viewers. Cutting into a uPVC door for a traditional mortice lock is not something we would do, and anyone offering it should be questioned.
Do you fit door viewers, chains and restrictors?
Yes, and they are among the most worthwhile things we fit. A viewer and a restrictor together mean you can deal with an unexpected caller without opening the door properly, which matters more than any lock for people living alone or answering to strangers regularly. They take minutes to fit and cost very little compared with the reassurance.
What are hinge bolts and does my door need them?
They are steel pins fitted into the hinge edge of the door that engage a plate in the frame as it closes, so the door cannot be levered off on the hinge side even if the hinges are attacked. Outward-opening doors and older timber doors with exposed hinges benefit most. They are inexpensive, invisible when the door is shut, and fitted in well under an hour.
Can you fit locks to internal doors, sheds and gates?
Yes. Internal doors usually take a simpler lock or a privacy latch and the consideration is the door construction, since many modern internal doors are hollow with only a small solid block to work with. Sheds, gates and outbuildings take hasps, padlock bars and closed-shackle padlocks, which can be keyed to match your other locks if you ask when booking.
A builder hung my new door but did not fit the locks. Can you finish it?
That is a job we do regularly and it is entirely normal — joiners hang doors, locksmiths fit locks. Send a photograph of the door and the frame and tell us what is already there. We check the door hangs squarely first, because fitting a lock to a door that has been hung out of true guarantees a mechanism that binds within months.
How long does a fitting take?
A mortice deadlock into a door that has never had one is usually an hour to ninety minutes done properly, because the cutting is the slow part. Hinge bolts, viewers, chains and restrictors are typically twenty to thirty minutes each. Several small items fitted in one visit is much better value than booking them separately.
Will you make a mess of my hallway?
Cutting a mortice makes shavings, and we work with a sheet down and take the waste away with us. Where a door has been painted many times, we are careful about where the chisel breaks the surface so the finish is not chipped beyond the area the face plate covers. It is worth mentioning on booking if the door is a period one you would rather not see touched up.
How is lock fitting priced?
By what is being fitted and how much cutting it needs, and quoted before we travel. Hanging small hardware on an existing door is at the modest end; cutting a fresh mortice into a solid period door is the larger job. If you are having several things done at once, say so when booking, because the visit is priced as a whole rather than item by item.