BS 476 vs EN 1634: UK Fire Door Testing Standards Explained

Why are there two fire door testing standards in the UK?

A fire door only earns its rating through a furnace test on a full-size doorset. In England, two test standards have run side by side for decades: BS 476-22, the national fire resistance test dating from 1987, and BS EN 1634-1, the European test whose results are classified under BS EN 13501-2. The BWF Fire Door Alliance confirms that fire resistance is determined by testing full-sized constructions to "the appropriate fire test standard, BS 476: Part 22 or BS EN 1634-1" at UKAS-accredited laboratories.

Approved Document B — the statutory guidance supporting the Building Regulations 2010 in England — currently accepts either route for fire resistance. That dual system is ending. The government has confirmed a phased withdrawal of the national BS 476 classes, and the fire resistance stage takes effect on 2 September 2029. Understanding both regimes, and how FD ratings map onto E and EI classes, is now essential for anyone specifying, buying or approving fire doorsets.

How do the BS 476-22 and EN 1634-1 tests differ?

Both tests mount a complete doorset in a supporting construction in front of a furnace that follows the standard time-temperature curve, then observe how long the assembly holds back flames and hot gases. The differences lie in how the furnace is instrumented and pressurised — and they matter, because the European method is generally the more punishing of the two.

The BWF Fire Door Alliance explains the two headline differences: BS 476-22 uses unshielded thermocouples while "EN 1634-1 uses shielded thermocouples which are less responsive to changes in temperature, resulting in increased heating energy" early in the test, and "the neutral pressure plane is positioned lower in BS EN 1634-1 tests (500mm from the notional furnace floor level, compared to 1000mm in BS 476-22)". Industry testing experience, summarised by UK Testing & Certification, suggests these differences produce roughly a 5-20% reduction in measured performance when the same doorset design is tested to EN 1634-1 rather than BS 476-22.

The practical consequence: a doorset that passes EN 1634-1 will almost certainly satisfy the BS 476-22 criteria, but the reverse cannot be assumed. A BS 476-22 test report cannot simply be converted into an EN classification — demonstrating an E or EI class requires EN test evidence.

What do E, EI and EW mean under EN 13501-2?

BS EN 13501-2 is the classification standard that turns EN 1634-1 test data into a class. For fire doors, three performance criteria matter — integrity (E), insulation (I) and radiation (W) — and each class carries a number giving the minutes achieved.

E — integrity only

An E-classified door prevents the passage of flames and hot gases for the stated period, judged by criteria such as sustained flaming on the unexposed face, gap gauges and ignition of a cotton pad. It does not limit how hot the unexposed face becomes, so combustible materials close to the door could still ignite from transmitted heat. E30 and E60 are the nearest European counterparts to FD30 and FD60, because FD ratings are also integrity-based.

EI — integrity plus insulation

An EI-classified door satisfies the integrity criteria and additionally limits heat transfer through the doorset: the mean temperature rise on the unexposed face must not exceed 140°C for the classified period. Two variants exist — EI1 and EI2 — which differ in where thermocouples are placed near the edges and frame and in the maximum local rises permitted; EI1 is the stricter of the two, and EI2 is the variant normally used for doorsets. EI classifications are typically specified where people could be close to the door for a sustained period — protected stairways and lobbies in taller residential buildings, sleeping accommodation, and specifications written to BS 9991:2024 or project fire strategies that demand insulation performance.

EW — integrity plus radiation control

An EW-classified door satisfies integrity and also limits radiated heat, which as EBD Steel Doors summarises, "limits the radiant heat transfer to below 15 kW/m2 at a measured distance from the door" (measured 1m from the unexposed face). EW sits between E and EI: it protects people passing the door from radiant heat without providing full insulation. It appears more often in European specifications than in UK ones, but you will increasingly meet it on internationally specified projects.

Sa and S200 — the smoke classes

Smoke control is tested separately (BS EN 1634-3) and expressed as Sa — smoke leakage limited at ambient temperature only — or S200 — leakage limited at both ambient temperature and 200°C, the medium-temperature condition. These are the European counterparts of the UK's 's' suffix: FD30s broadly corresponds to E30 Sa or E30 S200, with the class chosen by the specification. Smoke-classified doorsets need effective smoke seals and controlled threshold gaps, exactly as an FD30s door does.

FD ratings to EN classifications: the mapping table

The table below gives the accepted working equivalence between the national FD ratings and the European classes. Treat it as indicative, not as a conversion: because the EN test is generally more onerous, an FD-rated design must still hold EN test evidence before it can claim the corresponding E class.

Two rules of thumb follow. First, when reading an EN classification, the letters tell you what is controlled and the number tells you for how long. Second, when comparing routes, equivalence only ever runs FD-to-E: there is no FD rating that demonstrates EI or EW performance.

What does Approved Document B currently accept?

As of mid-2026, Approved Document B in England accepts fire resistance demonstrated by either the national route (BS 476-22, FD ratings) or the European route (BS EN 1634-1 classified to BS EN 13501-2). For reaction to fire — surface linings, not fire doors — the national classes (Class 0, Class 1) have already been removed: that change took effect on 2 March 2025.

The government's amendment circular sets out the full phased timetable, which is confirmed and published, not a proposal:

The transition works on building control applications: work covered by an application deposited before a commencement date benefits from the stated transition period, after which the new guidance applies. In the circular's words, the update "removes the national classification system (BS 476) for fire resistance from Approved Document B" with effect from 2 September 2029.

One important nuance: design codes are moving ahead of the regulations. BS 9991:2024, the fire safety design code for residential buildings published in November 2024, already specifies fire doors by EN 13501-2 classification including smoke performance. For new residential design work following that code, the European era has effectively begun — three years before the Approved Document B deadline.

Does the 2029 phase-out make existing fire doors illegal?

No. Approved Document B is guidance for new building work. The 2029 change means that fire resistance for work approved under the Building Regulations will need European classification evidence; it does not retrospectively condemn doors already in service. The BWF Fire Door Alliance puts it plainly: "there is no need to replace fit-for-purpose fire doors that comply with the British Standard."

Existing doors continue to be governed by the occupied-building regime: the fire risk assessment and the maintenance duty under Article 17 of the Regulatory Reform (Fire Safety) Order 2005, plus — in residential buildings over 11m in England — the routine checks required by Regulation 10 of the Fire Safety (England) Regulations 2022 (communal fire doors at least every three months, flat entrance doors at least every twelve months on a best-endeavours basis). A well-maintained BS 476-tested door that passes its checks remains a compliant fire door.

Where the change does bite is on replacement and new supply as 2029 approaches: manufacturers are re-testing ranges to EN 1634-1, and legacy designs supported only by BS 476-22 evidence will progressively drop out of new work in England.

What should specifiers do today?

The sensible strategy in 2026 is to specify for where the regime is going, not where it has been. Every doorset we supply will carry third-party certification, and our advice to specifiers follows the same logic: buy evidence, not assertions.

1. Prefer EN evidence for new projects. Specify the classification you need to BS EN 13501-2 — for example E30 Sa, E60 S200 or EI30 — especially for residential work designed to BS 9991:2024 and any project that could complete near or after September 2029.
2. Decide deliberately between E and EI. Check the fire strategy: if insulation performance is required, say EI and require EN classification reports; if integrity is sufficient, do not over-specify EI where the market and the strategy support E.
3. Ask for the classification report and field of application, not just a certificate number. The field of application tells you whether your sizes, glazing, hardware and frame details are actually covered.
4. Use third-party certificated doorsets (for example Certifire, BM TRADA Q-Mark or IFC schemes) and confirm the certification scope includes the EN test route where you need it.
5. Keep the evidence. File test and classification reports, certificates and the installation records with the Regulation 38 fire safety information and, on higher-risk buildings, the golden thread.
6. For existing buildings, do not panic-replace. BS 476-22 evidence remains valid for doors in service; let the fire risk assessment and inspection findings — not the 2029 date alone — drive replacement decisions.