External Walls and Cladding
27. Although the functional standards remain fundamentally correct there was an identified need for minor changes to the wording for "Cavities" (2.4), to close a potential loop hole which is very occasionally being exploited around the words "unseen" and "concealed". One solution which might be considered is to use of the word "cavity" itself. It was also considered worth reviewing the functional standard for "Spread on External Walls" (2.7) to see if the wording should be modified to specifically include "rate of spread".
28. Considering the guidance within the Technical Handbooks it was agreed that there was no longer the need to retain both British Standards and European Harmonised tests in respect of "reaction to fire" in the guidance. When first published in 2004 an annex (annex 2.B in Domestic and annex 2.E in Non-domestic) had to be included to relate classes of "reaction to fire" performance in terms of both sets of standards. This is no longer necessary and does mean that some of the British Standard tests are still being used to assess materials, when the European Harmonised tests offer a better and more cohesive structure for testing "reaction to fire". In coming to this decision and considering the applicability of the current "reaction to fire" tests cited in the Technical Handbooks the Review Panel had been assisted by having seen the final draft of the Research on Regulatory Appropriateness of Currently Cited Reaction to Fire Tests in Technical Handbook – Section 2: Fire – Standards 2.4 – 2.7. undertaken for Building Standards Division by Brian Meacham.
29. The Review Panel recognised that consideration would have to be given to those products, which are approved under the currently cited British Standard "reaction to fire" test methods, but which have not been tested under the applicable European Harmonised "reaction to fire" test methods. Therefore such a change needs to be signalled to Industry as soon as possible and careful thought given to the possible need for a transition period, possibly say two years.
30. One benefit of only using the European Harmonised tests would be that this annex with the comparison table on "reaction to fire" for standards 2.4-2.7 would no longer be required. Instead the test classes could be cited directly in the relevant parts of the guidance. The specific classes denominators (A, A, B etc.,) could be used instead of more generic nomenclature (low risk, medium risk, etc.).
31. If the principle of having alternative guidance for compliance was adopted then for the prescriptive set of guidance, available for all to use, the following changes would also be made:
- In the guidance on "Cavities (2.4)" the guidance requires the use of A2 or better products under the Harmonised European reaction to fire test classes. This will have the consequence of reducing the distance between cavities barriers in cavities where there is category B material exposed from 20m to 10m.
- In "Spread on external walls" (2.7) the current table 2.9 in the Non-domestic Technical Handbook, and the relevant sections in Domestic, would now change so that in any building with a storey at over 11m above the ground it would require A2 or better.
- Further, for all entertainment and assembly buildings, residential care homes and hospitals it should only be A2 or better at any height.
- The requirement on insulation in high rise buildings (under 2.4.4 / 2.7.1 in the domestic and 2.4.6 / 2.7.2 Non-domestic Technical Handbooks) would be retained and take effect from 11m, rather than 18m.
32. The new 11m height is related to the height which might be able to be covered by a ground mounted water jet from fire-fighting operations.
33. The alternative guidance would still permit compliance with the functional standards to be shown by use of the tests set out in BS8414 (and BR135) as at present. In this manner innovation would still be possible, but the onus and expense of proving compliance would lie with the design team.
4. Changes are needed to the simple guidance on external
cladding, cavities and fire spread on external walls (2.4 –
4.1 Any building with a storey at over 11m above the ground should require A2 or better.
4.2 All entertainment and assembly buildings, residential care homes and hospital of any height should also be A2 or better.
4.3 BS8414 (and BR135) would remain as an alternative method of providing evidence to show compliance.
4.4 It is unhelpful and unnecessary to retain the British Standards as well as the European Standards in the guidance for "reaction to fire" tests.