Fire door access: specify the clear opening, not just the leaf size

A fire-door order says “900 mm door”. Before accepting that description, ask what the dimension means: the leaf itself, the outside of the frame, or the space available for someone to pass through?

Those dimensions are not interchangeable. JELD-WEN's ReadyFit sizing sheet, for example, separates leaf size, overall doorset size, structural opening and clear opening. It illustrates the distinction, not a universal sizing formula for other products. (jeld-wen.co.uk)

For your next project, make the required passage width an explicit part of the conversation before the doors are ordered.

Existing guidance, not a new deadline

This article concerns buildings other than dwellings in England. The government publication page provides Approved Document M Volume 2 incorporating the 2024 amendments. It is guidance supporting building regulations, not a new September 2026 fire-door rule. This article does not extend its provisions to Wales, Scotland or Northern Ireland. (gov.uk)

The practical issue is dimensional coordination: making sure the proposed door and its location deliver the intended access.

Understand the usable opening

Effective clear width means the available passage, allowing for obstructions such as the open leaf or projecting door furniture. Approved Document M's Diagram 9 shows the measurement across the opening, rather than along the leaf. (assets.publishing.service.gov.uk)

Its Table 2 distinguishes approach arrangements and new from existing buildings. For internal doors, paragraph 3.10(b) refers to the clear width through a single door or one leaf of a double door. The combined width of a pair is therefore not the only consideration. (assets.publishing.service.gov.uk)

Rather than choosing a familiar minimum from memory, ask the designer to identify the appropriate requirement for that particular location. Then ask the supplier to show how the proposed configuration achieves it.

For specifiers: describe the outcome before choosing the size

Our suggested approach is to put the required effective clear width alongside the proposed doorset dimensions. Ask for a drawing showing the frame, open leaf, relevant projecting hardware and surrounding layout. Keep the dimension names explicit: “door width” is too ambiguous for a decision that depends on which width is meant.

Consider an illustrative community-centre refurbishment. The buyer receives a leaf-size quotation, while the designer is expecting a specified clear passage. Both documents contain a width, but nobody has checked whether they describe the same thing. A short dimensional review before ordering is the opportunity to resolve that misunderstanding.

Bring access and fire-door design into the same discussion. GEZE's planning resource recognises that door design involves multiple considerations, including accessibility and fire safety; its commercial advice is not approval of a particular solution. (geze.co.uk)

Ask the project team to resolve the complete arrangement, rather than accepting a size in isolation.

For installers: check the setting-out information

Before starting the affected opening, consider a brief walk-through with the person responsible for setting out. Compare the proposed door position and surrounding construction with the coordinated drawing. Include the approach from both directions in the discussion, not just the opening viewed square-on.

If the site arrangement differs, describe the discrepancy precisely. For example: “The return wall is closer to the proposed frame position than shown on the drawing; please confirm the intended layout before installation.” That is more useful than reporting that the door “looks tight”.

Agree when the finished arrangement will be checked and who will assess any shortfall. Do not treat this article as permission to alter a fire-door assembly or redesign its surrounding construction on site.

One useful check before the next order

Take one proposed fire door and ask three questions:

• Which dimension is the supplier quoting?
• What effective clear width has the designer specified?
• Has the proposed arrangement been checked in its actual approach layout?

These are suggested coordination questions, not a complete compliance checklist. The aim is straightforward: settle the available passage before committing to a door size.

Sources checked: 19 September 2026. Source links appear alongside the relevant statements.