Approved Document B Explained: What It Requires for Fire Doors and Curtains

Approved Document B (Fire Safety) is the single most referenced document in UK passive fire protection specification, but it is worth being precise about what it actually is. It is not the law itself — it is statutory guidance issued to demonstrate one way of complying with the legal requirement, which is Part B of Schedule 1 to the Building Regulations 2010. A design that follows Approved Document B is deemed to satisfy Part B, but a design can also comply with Part B by other means, typically through a fire engineered approach under BS 7974. In practice, the vast majority of UK buildings are designed against Approved Document B directly.

Volume 1 and Volume 2

Approved Document B is published in two volumes. Volume 1 covers dwellings — houses and flats. Volume 2 covers buildings other than dwellings — offices, hotels, hospitals, retail, industrial and everything else a specifier working on non-residential projects is likely to encounter. The two volumes share the same underlying principles but differ in detail, particularly around escape distances, travel distances and compartment sizes, because the assumed occupant characteristics and evacuation strategies differ between a private dwelling and a large public building.

What It Says About Fire Doors

Approved Document B does not prescribe fire door products by brand or model — it sets out where fire-resisting doorsets are required, and to what standard of performance, expressed in the E/EI notation derived from EN 13501-2. Broadly, it requires fire doors at compartment walls, at the boundaries of protected escape routes such as stairway enclosures, and at openings into rooms or areas that present a particular fire risk, such as plant rooms or storage areas with a higher fire load. The specific period required depends on the building's height, its purpose group, and where the door sits in the overall means-of-escape strategy — which is why generic 'this door needs to be X minutes' answers are unreliable without reference to the specific building.

What It Says About Fire Curtains

Fire curtains are addressed less prescriptively than fire doors in Approved Document B itself, in part because they are typically specified in situations — large atria, wide unobstructed spans — that fall outside the document's simpler tabulated guidance and instead rely on a fire engineered assessment referencing BS 9999 or a bespoke fire strategy. Where fire curtains are used to complete a compartment line or to form a smoke reservoir boundary, they are expected to be tested to the same EN 1634-1 and EN 12101-1 standards referenced for other compartmentation elements, and classified under EN 13501-2 in the same E/EI/EW notation used for fire doors.

The 2024 Amendments

Approved Document B has been amended several times since its last full republication, most recently with amendments that take effect from 30 September 2026. These amendments remove several references to the legacy BS 476 series for reaction-to-fire and roof coverings, continuing a long-running transition towards the harmonised European EN 13501 series as the primary basis for classification referenced in UK guidance. Specifiers working on projects that will complete after this date should confirm which edition of Approved Document B applies to their building control submission, as transitional arrangements typically apply around amendment dates.

Using Approved Document B in Practice

• —Treat Approved Document B as guidance to a legal requirement, not the requirement itself — a fire engineered alternative is always possible, but needs to be justified and agreed with building control.
• —Confirm which volume applies — Volume 1 for dwellings, Volume 2 for everything else — and use the correct one for the building type.
• —Always express the required fire door or curtain rating in EN 13501-2 notation (E, EI, EW plus minutes) rather than a legacy classification, to avoid ambiguity with building control and other consultants.
• —Check the current amendment status before finalising specifications on long-running projects, particularly those spanning the 30 September 2026 transition date.
• —Where a fire curtain or unusual compartmentation solution falls outside Approved Document B's tabulated guidance, reference BS 9999 or commission a fire engineered assessment rather than assuming a default period applies.

BÖLDT's fire doors and fire curtains are tested to EN 1634-1 and EN 12101-1 and classified to EN 13501-2, giving specifiers a directly comparable basis for demonstrating compliance with Approved Document B on UK projects. Our technical team can map a specification against the current edition for a specific building on request.