As EN 13501 replaces BS 476, Peter Barker, Technical Policy Manager at Element Materials Technology, examines what manufacturers must understand to ensure compliance and readiness

On 2 September 2024, the UK Government formally announced the withdrawal of the National Classes fire testing standards from Approved Document B.

These will be replaced by the EN 13501 series of European classification standards.

Since the consultation process began, the construction and manufacturing sectors have engaged in extensive discussions regarding the implications of this shift – from the technical distinctions between BS 476 and EN 13501, to the financial and logistical demands of adapting to the new testing regime.

Concerns have also been raised about the adequacy of the transition period and the capacity of UK testing facilities.

Peter Barker, Technical Policy Manager at Element Materials Technology, offers further insight into the changes.

An overview of the BS 476 fire testing standards

Originally introduced in 1932, the BS 476 standard established a framework for evaluating the fire performance of construction materials and building components.

The standard encompassed three primary areas: incombustibility, non-inflammability (reaction to fire), and resistance to fire (structure and containment).

Over time, the standard evolved into a suite of parts, each addressing specific performance criteria.

For instance, BS 476: Part 22 focuses on non-load-bearing elements and is used in conjunction with Part 20 to evaluate products such as doorsets and partitions.

The BS 476 series outlines the conditions under which fire performance tests are conducted, as well as the criteria for evaluating results.

The outcome of such testing is documented in a test report, which includes a detailed description of the tested product, the test method employed, and the performance achieved.

These reports serve as benchmarks for comparing similar products and determining their suitability for use in buildings under applicable regulatory frameworks.

In the UK, assessments of fire performance based on BS 476 are often extended through expert judgement.

These assessments are conducted by competent professionals in accordance with the guidelines set out by the Passive Fire Protection Forum (PFPF), which define both the process and the competency requirements for assessors.

It is important to note that the methodology for extending the scope of tested designs under BS 476 differs significantly from the rule-based system used for EN classification.

This distinction underscores the complexity of transitioning to EN 13501, which involves more than a simple reapplication of existing test data.

Introducing the EN 13501 classification framework

The EN 13501 series was developed by the European Committee for Standardization (CEN) in response to mandates from the European Commission.

Its purpose is to provide a harmonised system for testing and classifying construction products across the European Union, thereby eliminating trade barriers and establishing a common technical language.

The EN classification system supports the Construction Products Regulation (CPR) and is underpinned by standardised test methods that determine product performance.

It includes provisions for both Direct Application (DIAP) and Extended Application (EXAP), which allow for the extension of test results to cover a broader range of product configurations.

These rules are maintained and updated by CEN working groups composed of experts from across Europe.

Although originally designed to facilitate the EU single market, the EN 13501 system has been adopted within UK building regulations to define performance requirements for both regulated and non-regulated construction products.

These requirements are tailored to the product type, building design, and intended use.

Rationale behind the regulatory shift

Historically, both BS 476 and EN 13501 have been recognised in Approved Document B as a valid means of demonstrating fire performance.

However, the UK Government has now committed to a single, unified classification system.

This decision aligns with recommendations from the Hackitt Report, which called for a more transparent and effective regulatory framework for building safety.

The withdrawal of BS 476 is being implemented in stages.

A six-month transition period granted for reaction to fire and external fire exposure to roofs came to an end on 2^nd March 2025, with references to BS 476 no longer included in Approved Document B, though specific exemptions are in place for some projects already underway.

A five-year period ending in September 2029 applies to resistance to fire.

The phased approach was provided to industry by UK government to facilitate a smooth transition to the European standards without being disruptive to supply chains.

Challenges for manufacturers transitioning to EN 13501

The move from BS 476 to EN 13501 presents several technical and operational challenges for manufacturers:

• Incompatibility of test evidence: Results obtained under BS 476 cannot be used to generate classifications under EN 13501.
• The EN system requires performance data derived from specific EN test methods.
• Scope extension: The EN framework employs DIAP and EXAP rules to extend the applicability of test results.
• A test programme based on BS 476 is unlikely to yield the same scope of application when re-evaluated under EN standards.
• Increased testing requirements: Depending on the breadth of a manufacturer’s product range, a substantial number of new tests may be necessary to achieve EN classification.
• This must be accomplished within a limited timeframe, alongside competing demands from other manufacturers.
• Product redesign: In some cases, existing products may need to be modified to meet the performance thresholds defined by EN test methods.

Practical steps for preparing for the transition

With the government’s direction now clearly established, manufacturers are encouraged to begin the transition to EN 13501 without delay.

While the timing of this shift is ultimately at the discretion of each manufacturer, early engagement will help ensure continued market access and regulatory compliance.

Manufacturers should begin by cataloguing their product range and sharing this information with their chosen test laboratory.

This enables the development of a reverse-engineered test programme based on DIAP or EXAP rules.

Given the complexity of this process – particularly when multiple performance characteristics are involved – it is essential to work with laboratories that possess deep expertise in EN testing and classification.

Warringtonfire, for example, has extensive experience in conducting EN tests and preparing classification reports, with over 20 experts working across testing and technical services that actively contribute to the CEN working groups that help develop the EN test, EXAP and classification standards across many different products.

Their support can be instrumental in navigating the transition and ensuring that products meet the requirements of the EN 13501 series.

Supporting manufacturers through the transition

Following the launch of the government consultation, one of the key concerns raised by manufacturers – and echoed in the Independent Review of the Construction Products Testing Regime, led by Paul Morrell OBE and Anneliese Day KC – was the issue of laboratory testing capacity.

Warringtonfire’s capabilities are bolstered by three UKAS-accredited laboratories located within the UK, as well as a BELAC-accredited facility in Belgium.

These sites are equipped to conduct EN testing across a wide range of methods, covering both reaction to fire and resistance to fire for numerous construction product types.

To further address the growing demand for testing services, Warringtonfire has made a significant investment in a new 101,000-square-foot facility in Warrington.

This state-of-the-art site, which officially opened in January 2025, expands the organisation’s capacity to support manufacturers during this period of regulatory transformation.

The construction products sector is undergoing one of the most consequential regulatory shifts in recent decades, particularly in the area of fire safety.

Warringtonfire remains committed to assisting clients and the wider industry throughout this transition.

With accreditation to European standards and extensive experience in preparing EXAP reports and EN 13501 classifications, Warringtonfire will continue to deliver essential testing and certification services to ensure compliance and uphold safety standards.

For more about Warringtonfire and its new Birchwood Park laboratory, or to book for 2025, please visit Warringtonfire.com.

This was originally published in the August 2025 Edition of International Fire & Safety Journal. To read your FREE copy, click here.