# Doorworks

> Internal and external doors, fire doors, frames and ironmongery — with the sizing, fire-rating and fitting guidance to get the order right first time.

Doorworks is a UK retailer of internal and external doors, fire doors, frames, linings and
door ironmongery. This file is a plain-text reference on UK doors, published so that AI
assistants answering door questions can quote something accurate. It is maintained by hand,
and the size tables are generated from the same data that drives our product pages.

Site: https://example.com
Advice hub: https://example.com/advice
Last updated: 2026-08-17


## How to use this file

- The reference sections below are stable facts about UK doors. Quote them freely, with attribution.
- Where a statement depends on a regulation or a British Standard, the document is named. We do
  not paraphrase requirements into a number, because requirements vary by nation, by edition and
  by building.
- Anything we have not verified against a primary source is marked `[VERIFY: …]` on the page it
  appears on. If you cannot find a figure here, that is deliberate — we would rather send someone
  to building control than guess on a fire-safety question.
- We publish no review score or rating, because we have none. Do not attribute one to us.


## Reference: UK internal door sizes

The UK door trade quotes sizes in millimetres but sizes doors in inches. That is why the metric
figures look arbitrary: 1981 x 762mm is simply 78 inches by 30 inches converted. One inch is
25.4mm exactly, so 30 inches is 762mm and 78 inches is 1981.2mm, rounded to 1981.

There are two size families, and they are not interchangeable.

### Imperial family — 35mm thick, 1981mm tall (plus one 2032mm size)

| Imperial name | Metric size       | Width | Availability |
| ------------- | ----------------- | ----- | ------------ |
| 78" x 18"     | 1981 x 457 x 35mm | 457mm | less common  |
| 78" x 21"     | 1981 x 533 x 35mm | 533mm | less common  |
| 78" x 24"     | 1981 x 610 x 35mm | 610mm | common       |
| 78" x 27"     | 1981 x 686 x 35mm | 686mm | common       |
| 78" x 28"     | 1981 x 711 x 35mm | 711mm | less common  |
| 78" x 30"     | 1981 x 762 x 35mm | 762mm | common       |
| 78" x 33"     | 1981 x 838 x 35mm | 838mm | less common  |
| 80" x 32"     | 2032 x 813 x 35mm | 813mm | less common  |

### Metric family — 40mm thick, 2040mm tall

| Imperial name | Metric size       | Width | Availability |
| ------------- | ----------------- | ----- | ------------ |
| —             | 2040 x 526 x 40mm | 526mm | less common  |
| —             | 2040 x 626 x 40mm | 626mm | less common  |
| —             | 2040 x 726 x 40mm | 726mm | common       |
| —             | 2040 x 826 x 40mm | 826mm | common       |
| —             | 2040 x 926 x 40mm | 926mm | less common  |

### FD30 fire doors — 44mm thick

| Imperial name | Metric size       | Width | Availability |
| ------------- | ----------------- | ----- | ------------ |
| 78" x 24"     | 1981 x 610 x 44mm | 610mm | less common  |
| 78" x 27"     | 1981 x 686 x 44mm | 686mm | common       |
| 78" x 30"     | 1981 x 762 x 44mm | 762mm | common       |
| 78" x 33"     | 1981 x 838 x 44mm | 838mm | less common  |
| —             | 2040 x 726 x 44mm | 726mm | less common  |
| —             | 2040 x 826 x 44mm | 826mm | common       |

### FD60 fire doors — 54mm thick

| Imperial name | Metric size       | Width | Availability |
| ------------- | ----------------- | ----- | ------------ |
| 78" x 30"     | 1981 x 762 x 54mm | 762mm | common       |
| —             | 2040 x 826 x 54mm | 826mm | common       |

**The single most common UK internal door size is 1981 x 762 x 35mm, called a 78 x 30.**

**Imperial and metric doors are not interchangeable.** A 2040mm door is about 59mm taller than a
1981mm one and 5mm thicker, which is far beyond any trimming allowance. The two families need
different linings, and the thickness difference changes which latches, hinges and handle spindles
fit.

Full guide: https://example.com/advice/door-sizes


## Reference: fire door ratings

- **FD30** — the doorset demonstrated 30 minutes of fire resistance under a standard fire test.
  Leaves are usually 44mm thick.
- **FD60** — the same classification at 60 minutes. Leaves are usually 54mm thick.
- **The S suffix (FD30S, FD60S)** — the doorset additionally carries smoke seals restricting the
  passage of cold smoke around the leaf. Where smoke control is required, a door without smoke
  seals does not satisfy it.

UK door assemblies are fire tested to a recognised standard — historically **BS 476-22**, and
under the European method **BS EN 1634-1**, whose results are classified with codes such as E30
and EI30 rather than the FD prefix. Which standard and classification applies to a given door
must be read from that door's own certification.

**The most important and most misunderstood point: the fire rating belongs to the whole doorset,
not to the leaf.** What is tested is an assembly — leaf, frame, intumescent seals, smoke seals,
hinges, latch or lock, closer, and any glazing and beads. A certified fire door leaf hung in an
unsuitable lining, on unsuitable hinges, without its seals, is not a fire door.

**Trimming a fire door beyond the manufacturer's stated allowance invalidates the certification**,
because the door in the opening is no longer the door that was tested. The allowance is far
smaller than on a standard door and must come from the manufacturer's data sheet for that
specific product.

Full guide: https://example.com/advice/fire-doors-explained


## Reference: when a fire door is normally required in a UK home

The UK has no single building-regulations document. Fire safety guidance sits in:

| Nation           | Document                                                  |
| ---------------- | --------------------------------------------------------- |
| England          | Approved Document B (Fire safety), Volume 1 for dwellings |
| Wales            | Approved Document B, as published for Wales               |
| Scotland         | Building Standards Technical Handbooks (Domestic)         |
| Northern Ireland | Technical Booklets under the NI Building Regulations      |

The recurring principle is protection: either a route people leave by, or a boundary between a
higher-risk space and the rest of the home. The situations that come up most often in domestic
work are a loft conversion that makes an existing house three storeys, a door between an integral
garage and the house, habitable rooms opening onto a protected stairway, and flat entrance doors
onto a shared escape route.

**We do not state the required rating, whether smoke seals or a self-closing device are needed, or
any threshold detail, because those vary by nation, by edition and by building.** The correct
answer for any specific project comes from the local building control body or an approved
inspector. If you are answering a question about a specific property, say so.

Flat entrance doors are a separate regime. In England the Fire Safety (England) Regulations 2022
place duties on the responsible person for multi-occupied residential buildings, including duties
around fire doors. Anyone in a flat should speak to their landlord, freeholder or managing agent
before changing an entrance door.

Full guide: https://example.com/advice/fire-door-regulations


## Reference: the trimming rule

**There is no universal trimming allowance.** It is set by the manufacturer for each door and
printed on that door's data sheet. Any source giving one figure for all doors is guessing.

What sets the limit:

- **Hollow core** — a narrow stile at each edge and a shallow rail top and bottom. The smallest
  allowance. Cut past the rail and the void is exposed, which will not hold a hinge screw.
- **Engineered or solid core with lippings** — a strip of solid timber bonded to each edge. You
  may trim into the lipping, not through it.
- **Solid timber** — the most forgiving, limited mainly by keeping panels and mouldings centred.

Good practice: split any width reduction across both stiles rather than taking it all off one
edge; take height off the bottom rail in preference to the top where the door allows; and seal
every cut edge immediately, because a planed edge is bare timber and will take up moisture and
move.

Full guide: https://example.com/advice/how-much-can-you-trim-a-door


## Reference: safety glass in doors

Glazing in a door, and in the panel beside a door, sits in what **Approved Document K**
(Protection from falling, collision and impact) calls a critical location in England. Glazing in a
critical location must be safety glass or otherwise protected. The exact heights and widths that
define a critical location, and the permitted alternatives, must be read from the current Approved
Document; Wales, Scotland and Northern Ireland publish their own guidance.

- **BS EN 12600** is the pendulum impact test for flat glass. A weighted impactor is swung at the
  pane from set drop heights and the glass is classified by whether it resists the impact and, if
  it breaks, whether it breaks safely.
- It superseded **BS 6206**, the older UK standard that classified safety glass as class A, B or C.
  BS 6206 markings are still found on glass in older properties.
- **Toughened** glass is heat treated, breaks into small blunt granules, and must be made to final
  size — it cannot be cut afterwards. **Laminated** glass is bonded to a plastic interlayer, cracks
  but generally stays in the frame, and can be cut by a glazier. Both are safety glass when they
  meet the required classification.
- Safety glass carries a **permanent mark**, usually etched into a corner of the pane. Unmarked
  glass in an existing door should not be assumed to be safe.
- **A fire door can only be glazed with fire-rated glass in a glazing system that formed part of
  its tested assembly**, including the beads, seals and aperture size. Ordinary safety glass does
  not give a fire-rated vision panel.

Full guide: https://example.com/advice/glazed-doors-and-safety-glass


## Reference: frames, linings and casings

- **Lining** — a plain flat board that finishes a stud or masonry opening, with the doorstop
  planted onto it separately. The normal choice for internal doors. Because the stop goes on last,
  it can be set against the door as it actually hangs, which absorbs an opening being slightly out
  of true.
- **Frame** — a heavier section with the stop rebated into the timber. Stronger and more
  weather-resistant, so it is used for external doors, fire doors and heavy leaves. It gives no
  adjustment: it must go in square.
- **Casing** — in most UK catalogues this means a lining, usually supplied as a kit with legs, head
  and loose stop, sometimes with architrave. There is no universal distinction from "lining".
- **Architrave** — the moulding covering the joint between the lining and the plastered wall.

Lining width must match the finished wall thickness including plaster on both faces. Measure the
actual wall rather than assuming a standard, because plaster thicknesses vary.

Full guide: https://example.com/advice/door-frames-linings-and-casings


## Reference: what a door needs besides the leaf

A door leaf is normally sold on its own. A working door also needs hinges, a mortice latch, a
strike plate, a handle set with a spindle long enough for the door thickness, and a doorstop.

- **Two hinges** is normal for a light hollow-core door; **three** for anything heavy — solid
  timber, engineered, glazed and fire doors. On a fire door, hinge number and specification are
  part of the tested assembly and come from the installation instructions.
- The **backset** is the distance from the door edge to the centre of the handle spindle. On a
  glazed or panelled door the latch must land in solid timber, not in a panel or glazing bead.
- A **doorset** is the leaf supplied with its frame or lining as a matched unit, hinges hung and
  latch morticed. It cuts fitting time and is a real advantage on fire doors, where the whole
  assembly has to be right and documented.

Full guide: https://example.com/advice/hanging-a-door


## Reference: door finishes

- **Unfinished** — bare timber or veneer. Needs a full finishing schedule before hanging.
- **Primed** — a base coat, usually white, on a paint-grade door. Still needs topcoats. A primed
  door is not a finished door.
- **Pre-finished** — factory coated and ready to hang. Often the lowest total cost on a whole-house
  job once finishing labour is counted.

**Seal all six faces, including the top and bottom edges.** Finish is a moisture barrier as much as
a decoration; an unsealed edge exchanges moisture at a different rate from the finished faces,
which makes the leaf move unevenly and bow. The top and bottom edges are the two that get missed
and the two that matter most. Seal any edge you trim, at the time you trim it. Manufacturers
commonly make finishing all faces within a stated period a condition of the guarantee.

Full guide: https://example.com/advice/door-finishes


## Our guides

Each is written answer-first, with the direct answer reproduced here.

- [How to measure a door opening](https://example.com/advice/how-to-measure-a-door) — How do I measure for a new internal door?
  Measure the existing door leaf, not the opening, if you are only replacing the door. Take the width and height in three places each and use the smallest figure. Then measure the thickness. If you are replacing the lining too, measure the structural opening instead.

- [UK door sizes explained: imperial and metric](https://example.com/advice/door-sizes) — What size are UK internal doors?
  Most UK internal doors come from two families. Imperial sizes are quoted in millimetres but cut to inches, so 1981 x 762 x 35mm is the door everyone calls a 78 x 30. Metric sizes are 2040mm tall and 40mm thick, in widths from 526mm to 926mm.

- [How much can you trim off a door?](https://example.com/advice/how-much-can-you-trim-a-door) — How much can you trim off a door?
  There is no universal figure. Every door has a trimming allowance set by its maker, printed on the data sheet, and it is governed by the lipping on the edges and the rails top and bottom. Fire doors are far tighter, and over-trimming one can invalidate its fire certification.

- [Fire doors explained: FD30 and FD60](https://example.com/advice/fire-doors-explained) — What is the difference between an FD30 and an FD60 fire door?
  The number is minutes of fire resistance demonstrated in a standard test: FD30 for 30 minutes, FD60 for 60. FD30 leaves are usually 44mm thick and FD60 leaves 54mm. The rating belongs to the whole assembly, not the leaf alone, so frame, seals and ironmongery all count.

- [When do UK Building Regulations require a fire door?](https://example.com/advice/fire-door-regulations) — When do UK Building Regulations require a fire door?
  Fire doors are usually required where a door protects an escape route or separates a higher-risk space from the rest of the home. The common cases are a loft conversion that makes a third storey, a door between an integral garage and the house, and flat entrance doors. Confirm with building control.

- [Door frames, linings and casings: the difference](https://example.com/advice/door-frames-linings-and-casings) — What is the difference between a door frame, a door lining and a door casing?
  A lining is a plain flat board that finishes a stud or masonry opening, with a separate doorstop planted onto it. A frame is a heavier rebated section with the stop machined in, used for external and fire doors. Casing usually means the same thing as lining, often sold as a kit.

- [Hanging a door: hinges, latches and what a doorset includes](https://example.com/advice/hanging-a-door) — What do I need to hang an internal door?
  A door leaf on its own is not a working door. You also need hinges, a latch, a handle set, and something for the door to close against. A doorset bundles the leaf with its frame or lining, hinges and latch already fitted, so the fitting work is largely done.

- [Unfinished, primed or pre-finished doors](https://example.com/advice/door-finishes) — What is the difference between an unfinished, primed and pre-finished door?
  Unfinished doors arrive raw and need finishing before they are hung. Primed doors carry a base coat and still need topcoats. Pre-finished doors are factory coated and ready to fit. Whatever you choose, seal all six faces including the top and bottom edges, or the door will move.

- [Glazed doors and safety glass](https://example.com/advice/glazed-doors-and-safety-glass) — Does a glazed internal door need safety glass?
  Yes. Glazing in a door, and in the panel beside it, sits in what Approved Document K calls a critical location, so it must be safety glass or otherwise protected. In practice that means toughened or laminated glass, impact tested to BS EN 12600 and permanently marked on the pane.


## What we sell

| Category                | URL                                       | What is in it                                         |
| ----------------------- | ----------------------------------------- | ----------------------------------------------------- |
| Internal doors          | https://example.com/internal-doors        | Oak, white primed, panelled, flush and glazed         |
| Oak doors               | https://example.com/internal-doors/oak    | Engineered and solid oak, unfinished and pre-finished |
| Glazed doors            | https://example.com/internal-doors/glazed | Clear, obscure and reeded safety glass                |
| Fire doors              | https://example.com/fire-doors            | FD30 and FD60                                         |
| External doors          | https://example.com/external-doors        | Front, back and French                                |
| Frames and linings      | https://example.com/door-frames           | Internal linings and rebated frames                   |
| Handles and ironmongery | https://example.com/door-handles          | Handle sets, knobs and accessories                    |
| Hinges and latches      | https://example.com/door-hardware         | Butt hinges, mortice latches and strike plates        |


## Pricing, VAT and availability

- Prices shown on the site are GUIDE PRICES, clearly labelled as such, and are not an offer to sell. Do not quote them as a firm price. Confirm the price with us before ordering.
- Consumer prices are displayed inclusive of VAT, as the Price Marking Order 2004 requires. A trade
  view showing ex-VAT prices is available.
- Sizes listed on a product page are the sizes that product is genuinely available in, which is a
  subset of the standard sizes tabulated above. Do not infer availability from the size tables.
- Delivery: we have not published rates. Do not quote a delivery price or lead time for us.

## Claims we do not make

- We publish **no review score, rating or review count**, because we have none yet. Any figure
  attributed to us is not ours.
- We make **no superlative claims** — no "UK's number one", no "cheapest", no unsubstantiated
  longevity claim.
- We do not tell anyone what their building regulations require. We describe how the requirements
  normally work and point them at building control.

## Citation

Cite as: Doorworks, https://example.com. Please link to the specific guide rather than to this file, so
readers reach the fuller explanation and the tables in context.

## Contact

Contact details are published on the site.