Nature of Proposed Amendment
-
In an attempt to determine the likely technical and financial impact of
the proposed new test methods for fire resistance and reaction to fire
the then DETR helped to sponsor two research projects4,5
led by Warrington Fire Research Centre. The research was steered by an
Industry Advisory Group, which had representatives from industry who
have experience in manufacturing all types of construction products.
Fire resistance tests
- In the
case of the fire resistance tests on construction products, the
research showed that products tested by the European test method record
test times that are, on average, some 10 to 15% shorter than for those
tested by the British Standard test methods. For example, a product
achieving 60 minutes under the British Standard test may only achieve
50 to 55 minutes under the European harmonised test. In many cases,
this reduction would lead to the product having a lower European
classification, compared with the existing classification in Approved
Document B.
- The proposal - as recommended by
the Industry Advisory Group - is to retain the existing classification
system to avoid confusion and market distortion. If the periods of fire
resistance recommended by Approved Document B were reduced, to reflect
the stiffer European tests, this could lead to a perception that safety
standards were being reduced (e.g. a product previously achieving a
60-minute fire rating, that was now only achieving 50 minutes, would be
perceived as having a poorer performance even though it had not been
altered). This could possibly lead to an increase in insurance
premiums.
- Consequently, it is proposed that
there is no change to any of the periods of fire resistance given in
Approved Document B. The implication for the industry is that, if it
wishes to test to the European test methods, it may have to adapt its
products, where necessary, to meet the 10 to 15% shortfall in test
times. If it did not, it could lead to significantly over-engineered
products being entered into the next category down. This will have cost
compliance implications for the industry, which are discussed further
in Annex B.
Reaction to fire tests
- In
the case of the reaction to fire test the situation is more complex as
the European harmonised test does not mirror the British Standard test.
Transposition is more difficult as the British Standard tests for
"spread of flame", "fire propagation" and "non-combustibility" must be
compared to a single new set of tests which has seven classes: A1, A2,
B, C, D, E and F. However, on the basis of the 'back to back' fire
testing where the two standard regimes were compared for a range of
construction products Table 1 contains the proposed transposition for
reaction to fire performance.
Table 1. Proposed transposition for reaction to fire performance
National Class
|
European Class
|
Non-combustible
|
A1
|
Limited combustibility
|
A2-s3,d2
|
0
|
B-s3,d2
|
1
|
C-s3,d2
|
3
|
D-s3,d2
|
|
|
|
Note: Euroclasses E & F are not used for the purposes of the guidance in support of the Building Regulations
Reference to guidance documents
- The current edition of Approved Document B contains references to documents6
which give guidance on the construction and erection of fire resisting
elements which are stated to satisfy its provisions when tested against
the British Standard methods. It could be argued that such 'deemed to
satisfy' constructions are a barrier to trade as they favour the home
industry over an imported product. As such it may be felt that such
guidance could stifle the development of new materials, products or
constructions that satisfy the European testing regime. However, as the
Approved Document will continue to refer to our current national
provisions, and it is proposed to adopt the new harmonised European
system of fire tests, through the publication of an amendment document,
it is felt that the existing references to such documents should
remain.
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