British Standard tests: BS 476 series

Area of performance

Test used

Results expressed as

Fire resistance (to provide structural protection)

BS 476 Part 20 to 24

21: load bearing elements

22: non load bearing elements

23: components

24: ventilation ducts

Number of minutes for each of the characteristics:

  • Stability
  • Integrity
  • Insulation

Roofs’ resistance (to prevent fire spread from an adjoining building)

BS 496 Part 3

Two letters rating:

The roofs’ surface spread of flame

The roofs’ resistance to penetration by fire

AA is the best result achievable. DD is the worst

Surface spread of flame (to prevent fire spread to adjoining buildings)

BS 476 Part 6 and 7

Class varying from 0 to 4. The best result achievable is class 0


This test measures the performance of a wall when exposed to heat from one face. Firstly, its integrity. That is, the ability of a system to prevent the penetration of hot gases and flames. Secondly, the insulation of that wall. The test looks at the ability of the system to reduce the temperature rise on the unexposed side of the fire and therefore prevent fire spread through radiated heat.

The test may be carried with the wall section in either a load- or non load-bearing condition.

This is an external fire exposure test for roofs which simulates the effect of burning material falling on to a roof from an adjacent building. The test specimens consist of a representative section of roof. Testers record the length of time which the sample continues to burn, the spread of flame and the degree of penetration. They then grade the materials for surface spread of flame (from A to D) and the roof system for resistance to penetration by fire (from A to D).

A coal-gas flame is applied to the sample under three different conditions:

  • 1 minute stationary, with no additional heaters.
  • 3 minutes stationary with 2 radiant heaters.
  • 1 minute, moving flame, with 4 radiant heaters.

The air pressure underneath the test panel is reduced during the test.

The building regulations provide a notional designation of grade AA for roofing systems using Colorcoat® products.

This test measures the rate of heat release during combustion. Heat release during combustion will affect the rise in temperature of surrounding unburnt material and subsequent rate of spread of fire.

The sample is mounted and subjected to 14 gas jet flames at intervals across the sample width. Two electric heaters generate a high background temperature. The temperature rise is measured using thermocouples and compared with the rise obtained with a standard asbestos cement board specimen.

This test shows how the spread of flame across the surface of a material gives an indication as to its ability to spread fire.

The sample is mounted in a water-cooled holder and exposed to the radiant panel for 10 minutes with a pilot flame applied for the first minute of the test.

The progression of the flame front is measured aftern 11/2 minutes and at the end of the test. The test grades material from 1 (best) down to 4 (worst).

All Colorcoat® products achieve class 1 in this test.


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The Building Regulations - Fire

The basic concepts are the same in all the regions of the UK and Ireland, but it is worth noting that, because of its inherent strength, pre-finished steel roof and wall cladding complies very easily with the fire regulations in most situations.

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