There is a frustrating moment that plays out far too often: the lock arrives, the box is opened, and the new owner discovers the case is wider than the frame it needs to sit in. The door cannot take it. Most of the time, that mistake traces back to a single skipped step: measuring the door properly before ordering. This guide walks you through what to measure, why the stile of your door determines almost everything, and how a narrow-stile keypad lock differs from a standard one. By the end, you should be able to choose with confidence rather than guesswork.
Quick Answer
If your door stile measures under roughly 100mm wide, you will usually need a narrow stile lock with a shorter backset, commonly around 28mm. This is the typical case of aluminium-framed trances.
If your door has a wider timber or composite stile, a standard lock with a 44mm to 70mm backset is normally suitable.
Before buying, measure these five things:
- Stile width on the lock edge
- Door thickness
- Existing backset, if a lock is already fitted
- Bore hole position, if the door is already prepared
- Door handing, so the keypad sits correctly
Why The Stile Of Your Door Decides Everything
Before any talk of options, it helps to understand the part of the door that matters most here. The stile is the vertical section of timber, aluminium, or composite that runs down each side of a door. The lock edge stile, the one on the opening side, is where your keypad door lock physically lives. If that strip of material is too slim for the lock case you have chosen, it simply will not fit, or it will fit so tightly that the door is weakened.
Stile doors, particularly the aluminium framed ones common on shop fronts, offices, and modern glazed entrances, often have a stile only 45mm to 100mm wide. A traditional timber front door, by contrast, usually gives you a much more generous stile. That single difference, the width of the door stile, is the fork in the road. It is what distinguishes a narrow-profile lock from a standard one, and it is the first thing you should measure.
So the honest starting point is not “which option looks best” but “what will my door physically accept”. Get that wrong, and nothing else matters.
The Measurements You Actually Need To Take
You do not need specialist tools for this. A decent tape measure and, ideally, a small steel ruler for the tighter dimensions will cover almost everything. A digital calliper is a nice extra if you have one, though it is far from essential.
Here is what to record before you go anywhere near a product page:
- Stile width: measure the lock edge stile from the door’s edge inward to where the glazing or panel begins. This decides narrow versus standard.
- Door thickness: Most of these locks have a working range, so you need to know whether your door sits inside it.
- Backset of any existing lock: the distance from the door edge to the centre of the spindle or cylinder hole.
- Existing borehole position and diameter: relevant if you are retrofitting onto a door that is already cut.
- Door height and the latch position: so the keypad sits at a comfortable, usable height.
Write these down. Memory is unreliable, and a wrong figure recalled later is worse than no figure at all.
Measuring Your Door’s Thickness Using A Tape Measure
Open the door and measure across the edge, from the outside face to the inside face, at roughly the height the lock will sit. Take the reading two or three times at slightly different points, because doors are rarely perfectly uniform. Older timber doors in particular can vary by a millimetre or two along their length. Note the smallest and largest reading you get; the hardware has to work across that whole range.
Working Out The Stile Width And Backset
For the stile, measure from the leading edge of the door to the inner edge of the glass bead or panel. If you get something under roughly 100mm, you are almost certainly in narrow territory. For the backset, if a lock is already fitted, measure from the door edge to the centre of the spindle hole. Standard UK mortice backsets tend to be 44mm or 57mm, while narrow stile and aluminium door cases run much shorter, often around 28mm. A case built for 28mm will not line up with a door prepared for 57mm, and the reverse is equally true.
Which Doors Usually Need A Narrow Stile Lock?
It helps to know which door types fall into the narrow category before measuring, because the answer is often visible at a glance. A narrow stile lock is commonly needed on:
- Aluminium shopfront doors with slim framing
- Commercial glazed entrances where glass leaves little material
- Office entry doors of the aluminium framed type
- Steel framed gate systems using a compatible gate box
- Slimline patio and side doors with a reduced profile
If your door is solid timber or a fuller composite, you are very likely in standard territory instead. Still measure, but expect the wider stile.
Narrow Stile Keypad Locks Explained
A narrow stile lock is engineered for doors where there is very little material to work with. The case is slim, the backset is short, and the whole assembly is designed to drop into the kind of framing you see on aluminium commercial entrances and glazed doors.
Lockey Digital’s answer here is the LD930 narrow style latch, designed specifically to retrofit with the Lockey 2000 series. It has a 28mm backset, a 15mm throw on the latch, and an anti thrust pin built in. The case measures 176mm high, 25mm wide, and 44mm deep, which is what allows it to sit in framing that a fuller case would never enter. Usefully, those dimensions also mean it can replace an Adams Rite style lock, the most common cylinder lock found on aluminium doors across the UK. It is compatible with the 2430, 2435, 2835, 2430DS, 2835DS, and 7055 from the 2000 range, and it ships with a 110mm spindle and a strike plate. You can read the full specification on the LD930 product page.
There is also the Lockey 7070 from the Super 8 range, built for narrow stile aluminium doors and designed to retrofit with an Adams Rite 4710 lock case. Its slim profile is the headline feature, although the same model works perfectly well on standard doors too. The Super 8 series carries a patented code chamber, which we will come back to shortly, and the 7070 includes reversible lever handles plus a hold back facility. Full details sit on the Lockey 7070 page.
Where Narrow Stile Locks Make Sense
These are the situations where a slim case is the right call:
- Aluminium framed commercial or office doors with little stile to spare
- Glazed entrances where a fuller case would clash with the glass
- Replacing an existing Adams Rite cylinder lock with keyless access
- Gates using a compatible steel gate box, such as the Lockey GB930
- Any door where you measured a stile under roughly 100mm wide
The Trade-Offs To Be Aware Of
A slim case is a slim case. The shorter backset and reduced bolt throw are a consequence of the limited space, and that is simply the physics of narrow framing rather than a flaw. For the doors these are designed around, they are the correct and only sensible choice. The point is to match the hardware to the door, not to expect a narrow case to behave like a deeper one.
Standard Keypad Locks Explained
A standard lock is the one most homeowners picture: a fuller case, a longer backset, more room inside for a sturdier mechanism. These suit timber front doors, internal doors, garden gates with adequate framing, and most domestic entrances, where the stile gives you space to play with.
The Lockey 2835 is a good representative of the standard category. It is a mortise latch with a 60mm backset as standard, and here is the clever part: it is also available with an optional 70mm case, or a 28mm case for aluminium doors and gates. That flexibility means the 2835 platform can serve a wide range of doors, not just one. It carries a latch bolt with an anti-thrust pin, reversible lever handles, and both a hold-back facility and a free-passage function, either of which can be disconnected if you do not need it. It has also been fire tested in accordance with BS EN 1634-1: 2014 and BS EN 1363-1: 2012, which matters if the door is a fire door. That fire test reference should be verified against the current Lockey product data and confirmed with the client before publishing. The full specification is on the Lockey 2835 page.
For heavier traffic, the Lockey 1150 High Tech range is built for heavy-duty use, with durability as a design priority, and can be operated on both sides of the door. That makes it a strong fit for a busy front door or a commercial entry door that sees constant use.
What Standard Locks Give You
The advantages of a standard keypad lock, where the door allows one, include:
- A longer backset and fuller case, which generally means a more substantial mechanism
- Wider model choice across latches, deadbolts, and hook bolts
- Easier alignment with doors already prepared for a 44mm or 57mm backset
- Functions like free passage and hold back on models such as the 2835
- Straightforward fitting on the timber doors that most UK homes have
Narrow Stile vs Standard: The Direct Comparison
It helps to see the two side by side. The table below summarises the practical differences, though the sole deciding factor remains your measured stile width.
| Criteria | Narrow Stile Lock | Standard Lock |
| Best door type | Aluminium-framed, glazed, narrow profile | Timber, composite, fuller stile doors |
| Typical stile width suited | Under roughly 100mm | Generous stile, ample material |
| Typical backset | Short, around 28mm (LD930) | 60mm standard on the 2835, up to 70mm |
| Example models | LD930, Lockey 7070 | Lockey 2835, Lockey 1150 |
| Replaces | Adams Rite style cylinder locks | Conventional mortice and rim locks |
| Case profile | Slim, fits tight framing | Fuller needs an adequate style |
| Common use | Commercial and office entrances | Homes, gates, internal doors |
What this really shows is that the two are not competitors so much as answers to different doors. Choosing well is less about preference and more about honest measurement. A narrow case on a generous timber door is fine, if a little under-specified for the space available. A fuller case, however,e forced onto a slim aluminium frame, will not go in at all.
The 3 Most Common Measurement Mistakes
Most fitting problems trace back to the same handful of slips. Watch for these:
- Measuring the wrong part of the stile, or measuring the hinge edge instead of the lock edge
- Confusing backset with case depth, which are different dimensions entirely
- Assuming every keypad model fits timber and aluminium doors equally, when the stile width decides it
Avoid those three, and you have removed the bulk of the risk.
How To Make The Final Choice
Pull your measurements back out. If your lock edge stile came in narrow, the decision is effectively made for you: a slim case such as the LD930 or the 7070 is your route, and you should match the backset to whatever the door is already cut for. If the stile is generous and the door is timber, a standard lock like the 2835 offers more options, and you can then choose based on function, such as whether you want free passage or a hold-back feature.
One genuinely useful tip from fitters: consider door handing and the direction the door opens before you order. Lockey’s 2000 series locks are non-handed, and many models carry reversible lever handles, which removes a common source of error, but it is still worth checking. The 2835, for instance, has reversible lever handles, so a single product suits left- and right-hung doors.
Worth a mention too: the Super 8 series, including the 7070, uses a patented code chamber that lets you use the same digit twice in a code, for example, C2244. It is a small thing, perhaps, but it widens the range of memorable codes you can set, which matters more than people expect when several users need to recall a code daily.
If you are still unsure after measuring, that is the moment to ask rather than guess. A quick description of your door and its measurements is usually all it takes for the Lockey team to point you to the right model.
Frequently Asked Questions
What are the disadvantages of keyless door locks?
The main drawback people raise is that a forgotten code locks you out, since there is no key to fall back on, so codes need to be memorable and shared carefully. Mechanical models like the Lockey 2835 avoid the battery-related issues that affect electronic models, but any keypad can show wear on frequently pressed buttons over many years. Choosing hard-wearing construction and periodically updating the code address most concerns. For most users, the convenience of not carrying keys comfortably outweighs these points.
How do I know what size door lock to buy?
Start by measuring three things: your door thickness, the width of the lock edge stile, and the backset of any existing lock. The stile width indicates whether you need a narrow-profile model or a standard one. The backset must match what the door is prepared for, around 28mm for narrow aluminium doors or 44mm to 57mm for standard timber. The Lockey 2835 helps here by offering 28mm, 60mm, and 70mm case options, so one product line can suit several door types.
What are common mistakes when measuring doors?
The frequent errors are measuring the stile in the wrong place, recording the door thickness at only one point when doors vary along their length, and confusing backset with case depth. Another is forgetting to check door handing before ordering, although Lockey’s non-handed 2000 series locks reduce that risk. People also overlook the position of an existing borehole when retrofitting. Taking each measurement twice and writing down the figures rather than relying on memory prevents nearly all of these.
Do keyless locks affect home insurance?
Insurers in the UK typically specify lock requirements for external doors, and these often reference recognised standards rather than ruling out keyless designs outright. The sensible step is to check your policy wording and confirm with your insurer before fitting anything new. Some policies expect a particular standard of lock on the final exit door. If a specific certification matters for your cover, ask the Lockey team which model meets it, and confirm the details with your insurer in writing.
Get The Right Lock For Your Door
Measuring first, ordering second, is the whole secret to keyless entry that fits the first time. Browse the full range of narrow stile and standard keypad locks at lockeydigital.co.uk to compare models against your own measurements. If you would like a second opinion before you buy, send your door dimensions to the team at enquiries@lockeydigital.co.uk, and they will help you choose with confidence.
