BS 476 Part 22 Explained: The Standard Behind Fire Resistance Testing in the UK

Published on 06/10/2025

What You Need to Know About BS 476 Part 22

Fire protection in buildings isn’t just about alarms and sprinklers — it’s also about how walls, doors, and partitions hold up when exposed to flames. One of the key standards that has guided fire testing in the UK for decades is BS 476 Part 22, a benchmark for assessing how long non-loadbearing elements can resist fire.

Although the UK is transitioning toward European testing methods, this standard remains widely referenced and forms the basis for understanding how passive fire protection systems are evaluated.

The Role of BS 476 Part 22

This section of the BS 476 series focuses on non-structural components — elements that do not carry the weight of a building but are crucial to containing fire and smoke. These include:

• Fire doors and shutters
• Internal partitions
• Glazed screens and windows
• Ducts and dampers

BS 476 Part 22 works hand-in-hand with Part 20, which defines the furnace conditions, temperature curves, and pressure parameters for testing. Together, they allow laboratories to replicate realistic fire exposure scenarios and assess how long a product can maintain its performance before failure.

How the Test Is Conducted

When a specimen is submitted for testing, it’s installed in a furnace designed to replicate a growing fire. The furnace follows a controlled heating curve, rising rapidly to temperatures exceeding 1,000°C within minutes.

During the test, CFR technicians monitor:

• The structural behaviour of the element (cracking, warping, collapse)
• The temperature on the unexposed surface
• Any passage of flames or hot gases
• Radiation levels from the heated surface

Each specimen is tested until it no longer meets one or more performance criteria.

Understanding the Key Performance Criteria

BS 476 Part 22 classifies performance based on time to failure against two main measures:

1. Integrity (E) — The ability of a barrier to prevent the passage of flames or hot gases.
2. Insulation (I) — The ability to limit temperature rise on the side not exposed to the fire.

If either of these thresholds is breached, the test is stopped, and the failure time is recorded to the nearest minute. The resulting fire-resistance rating — such as 30, 60, 90, or 120 minutes — indicates how long the element performed effectively under the test conditions.

Why These Tests Matter

Fire-resistance testing serves multiple purposes:

• Public safety – ensuring that critical barriers can contain fire and give occupants enough time to evacuate.

• Building regulation compliance – meeting the performance requirements set out in Approved Document B.

• Product certification – helping manufacturers demonstrate that their products meet recognized safety standards.

• Design confidence – giving architects and engineers data they can rely on when specifying fire-rated assemblies.

Reading and Applying Test Reports

Every valid test generates a detailed report outlining the construction details, furnace performance, temperature readings, and visual observations. It’s vital to note that results only apply to the tested configuration.

Even small changes — such as the type of glass, seal material, or door frame — can affect the result. For variants or system changes, a new test or formal technical assessment is required to confirm equivalence.

Moving Toward European Standards

The UK is progressively shifting from BS 476 to EN-based standards, such as EN 1364 (for non-loadbearing walls) and EN 1634-1 (for doors and shutters). These tests use the same temperature curve but have different pressure profiles and instrumentation.

The government has already outlined transition dates:

• BS 476 references for reaction to fire will be withdrawn by March 2025.
• Resistance to fire testing under BS 476 will remain valid until September 2029.

After that, EN test evidence will be the accepted route to compliance under UK Building Regulations.

What the Industry Should Be Doing Now

1. Audit your test evidence – Check which of your current certificates are based on BS 476.
2. Plan retesting – Schedule EN tests ahead of the 2029 cut-off to avoid certification gaps.
3. Maintain installation quality – Even the best-tested system can fail if it’s not installed correctly.
4. Stay informed – Keep up with updates from BSI, UKAS, and the Department for Levelling Up, Housing and Communities (DLUHC).

Final Thoughts

BS 476 Part 22 has been the foundation of fire-resistance testing in the UK for decades, ensuring that non-structural components perform reliably during fire events. As the country transitions toward harmonised European standards, it remains essential for manufacturers, designers, and contractors to understand what this test measures — and how its principles continue to inform modern fire safety design.