Also online at: www.dijonline.co.uk 106 THE door industry journal spring 2025 Doorsets, Fire Doors, Safety & Security What is Happening to BS 476? Introduction to BS 476 The first version of BS 476 appeared as a single volume in 1932. It covered the testing of both reaction to fire (combustibility, surface spread of flame, etc.) of construction products and resistance to fire (mainly aimed at structural and compartmentation products, including doors). Reaction to fire focuses on events in the room where the fire starts, while fire resistance deals with the spread of fire outside the compartment where it originated. Following World War II, the experience of the Blitz in cities across the UK prompted further development of BS 476, which was revised and split into three parts. Part 1 covered fire resistance tests on doors, among many other things. The next major revision began in the late 1960s, resulting in the withdrawal of part 1 and its replacement by new parts 4 to 8. Part 8 covered the fire resistance testing, including for doors. In 1987, part 8 was withdrawn and, so far as door testing was concerned, replaced by the new part 22, or to give it its full title: BS 476-22:1987 Methods for determining the fire resistance of nonloadbearing elements of construction. By the early 1990s, the total number of parts of BS 476 had risen to 33, of which 14 are still current today, including part 22. This standard is, in many respects, similar to the European standard EN 1634-1, Fire resistance tests for door and shutter assemblies. Part 1: Fire doors and shutters. The two main differences between BS 476-22:1987 and BS EN 1634-1:2014+A1:2018 are the pressure regime (the EN requires a lower neutral pressure axis in the furnace) and the thermocouples used to measure the furnace temperature during the test (the EN uses plate thermocouples and the BS uses bead thermocouples). The result is that EN 1634-1 can be a slightly more severe test than BS 476-22, depending on the doorset being tested. Since BS 476-22 has a wider scope than EN 16034-1 and was also referenced in building regulations in the UK and Ireland, it was not withdrawn by BSI. The impact of Grenfell Following the Grenfell tragedy in 2017, in which 72 people lost their lives, attention was understandably centred on the way in which cladding and insulation materials had been tested and classified. This included reaction to fire (as opposed to fire-resistance) testing under BS 476. Consequently, references to the parts of BS 476 dealing with reaction to fire testing and classification are being removed from the English building regulations approved document B, with effect from 2nd March 2025. Unfortunately, fire door testing and classification to BS 476 have not emerged unscathed, although, in this case, the references are to be removed only in September 2029. It is difficult to see how fire-resisting testing and classification of doors to BS 476-22 might have contributed to the disaster. As noted above, the difference in recorded performance between a 30-minute door tested to BS 476-22 and the same door tested to EN 1634-1 is generally not significant. The move to EN 13501 classification The deletion of references to BS 476 will be important in one further respect, however. It is not just a question of re-testing products to a slightly different standard. The BS 476 test report does not extend the scope beyond the product tested. Any variation to the tested scope should be assessed by a test laboratory with the necessary level of expertise. Technical assessments in the UK use expert judgment to provide a scope of application using sufficient and relevant test evidence for the design. Assessing bodies in the UK follow the principles and guidance set out in the PFPF (Passive Fire Protection Forum) Guide to Undertaking Technical Assessments, which provides information on the process and the competency requirements for the product assessors responsible for preparing and checking the reports. This differs fundamentally from the requirements of the EN 13501 classification system accepted in Europe. This uses direct application (DIAP) and extended application (EXAP) rules (excluding expert judgment) to extend the scope of the tested designs. The result of moving to the EN 13501 system will typically be that either a reduced scope of product designs must be accepted or more testing will be needed to achieve a similar scope. Although September 2029 seems far away, testing capacity is finite and fire door manufacturers would be well advised to speak to relevant test houses to consider their options. The Door & Hardware Federation (dhf)’s General Secretary, Michael Skelding, discusses the origins of BS 476 and its continuing impact almost 100 years after its first publication.
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