Building standards - (fire safety) external wall systems: consultation analysis

4. Part 3 - Large Scale Fire Test, BS 8414

4.1 Introduction

4.1.1 Following the interim change to the Technical Handbook in April 2021 to remove reference to BS 8414 (and associated BR135) as alternative guidance, BSD have requested notification from local authority verifiers under Section 34 of the Building (Scotland) Act 2003 where BS 8414 (and associated BR 135) and extended field of application assessments (BS 9414) have been used to demonstrate compliance with the mandatory building standards.

4.1.2 The consultation set out four options relating to large scale fire test BS 8414 as follows:

• Option 1 – April 2021 Addendum: This option re-affirms the decision to remove reference to BS 8414/BR 135 from the Technical Handbook and to notify BSD when used as an alternative approach.
• Option 2 – Managed Use of BS 8414 to Address Risk: This option will cite reference to BS 8414/BR 135 in the Technical Handbook with tighter controls on the use and height of the building.
• Option 3 – Regulatory Ban: This option proposes a regulatory ban i.e. A1 or A2 only in regulation for residential buildings with any storey more than 18m.
• Option 4 – Any Alternative Proposal: This provides the opportunity for respondents to suggest alternative proposals for the Scottish Government to consider.

4.1.3 Table 5 provides a summary of the details of Options 1-3. The following points should be noted when interpreting the options:

• Any reference to storey height means the height of the topmost storey above the adjoining ground.
• For the purposes of this consultation ignore rules of measurement around sloping sites and topmost storeys consisting solely of plant rooms.
• Reference to European classification A1, A2, B, C, D and E means reaction to fire classification as set out in BS EN 13501-1.
• Supplementary guidance on the competence of designers, installers and verifiers of cladding systems as well as interpretation and use of fire test results will form part of a future consultation on compliance and contained within a new compliance handbook.
• The options exclude proposals for the ban on MCM (Category 3) as this is covered in Part 2 of this consultation.

Table 5: Summary of Options Relating to Large Scale Fire Test, BS 8414

	Option 1		Option 2		Option 3
	Performance2	Commentary	Performance5	Commentary	Performance5	Commentary
Domestic Buildings1
Any storey at a height of not more than 11m	B, C, D or E	Status quo	B, C, D and E	Status quo	B, C, D or E	Status quo
Any storey at a height of more than 11m	A1 or A2 or FSE approach3	Supplementary guidance in compliance h'bk
Any storey at a height of more than 11m and not more than 18m			A1 or A2 or BS 8414/BR135 or FSE approach3	Supplementary guidance in compliance h'bk	A1 or A2 or BS 8414/BR135 or FSE approach3	Supplementary guidance in compliance h'bk
Any storey at a height of more than 18m			A1 or A2 or FSE approach3	Supplementary guidance in compliance h'bk	A1 or A2 only (in regulation)	Supplementary guidance in compliance h'bk. No assessments in lieu of tests (AILOT) and/or FSE approach3
Entertainment, Assembly Buildings, Residential Care Buildings & Hospitals1
All buildings regardless of height4	A1 or A2 of FSE approach3	Supplementary guidance in compliance h'bk	A1 or A2 of FSE approach3	Supplementary guidance in compliance h'bk
Any storey at a height of not more than 18m					A1 or A2 or BS 8414/BR135 or FSE approach3	Supplementary guidance in compliance h'bk
Any storey at a height of more than 18m					A1 or A2 only (in regulation)6	Supplementary guidance in compliance h'bk. No assessments in lieu of tests (AILOT) and/or FSE approach3
All Non-Domestic Buidlings1 (Other than Entertainment, Assembly, Residential Care &Hospitals1)
Any storey at a height of not more than 11m	B, C, D or E	Status quo	B, C, D and E	Status quo	B, C, D or E	Status quo
Any storey at a height of more than 11m	A1 or A2 or FSE approach3	Supplementary guidance in compliance h'bk
Any storey at a height of more than 11m and not more than 18m			A1 or A2 or BS 8414/BR135 or FSE approach3	Supplementary guidance in compliance h'bk	A1 or A2 or BS 8414/BR135 or FSE approach3	Supplementary guidance in compliance h'bk
Any storey at a height of more than 18m			A1 or A2 or FSE approach3	Supplementary guidance in compliance h'bk	A1 or A2 or FSE approach3	Supplementary guidance in compliance h'bk

Notes:
1 Assume building more than 1m from boundary i.e. if < 1m to boundary cladding should achieve European classification A1 or A2 in accordance with BS EN 13501-1.
2 Any reference to A1 or A2 or FSE approach assumes that supplementary guidance will be provided in the new compliance handbook (to be developed).
3 Alternative FSE approach from first principles using BS 7974 or International fire engineering guidelines (IFEG). guidance in compliance handbook to restrict use of this approach to chartered / incorporated engineer registered with engineering council having skills, knowledge and [experience/expertise] of façade fire testing and construction.
4 Excludes small buildings as defined in the Non-Domestic Technical Handbook (NDTH) provided no storey more than 11m.
5 Any reference to A1 or A2 or BS 8414/BR 135 assumes that supplementary guidance will be provided in the new compliance handbook (to be developed).
6 May be extended to other residential buildings including hotels

4.2 Question 3 – Which of the Four Options is your Preferred Choice?

4.2.1 Question 3 asked respondents which of the options shown in Table 5 above was their preferred choice. Respondents could only select one option. Table 6 shows the results. Option 1 was favoured by 16% of respondents, but this option attracted the least support. Options 2 and 4 were preferred by 24% and 27% of respondents with Option 3 garnering the greatest support (33% of respondents).

4.2.2 Table 6 shows that support for the different options is broadly split across the different respondent categories. The main observations include:

• A slight majority (57%) of respondents from the consultancy category favoured Option 4.
• Half (50%) of individual and local authority respondents favoured Option 3.
• A slight majority (53%) of respondents from trade associations favoured Option 2.
• There was no clear support for one specific option across the other categories.

Table 6: Which of the Four Options is your Preferred Choice?

	Opt. 1	Opt. 2	Opt, 3	Opt.4	Not Answered	Total
Construction Industry	1	2	2	1	-	6
Consultancy	1	-	2	4	-	7
Individuals	1	5	11	5	-	22
Local Authorities	3	-	4	1	-	8
Manufacturers	1	2	1	2	1	7
Other	3	-	3	2	1	9
Research Estab./Fire Test House	-	-	-	1	1	2
Trade Association	1	8	-	3	3	15
Total	11	17	23	19	6	76
% respondents answering question	16	24	33	27		100

4.2.3 There were 56 comments made in response to this question. Comments are presented separately for each individual option.

Option 1 – April 2021 Addendum

4.2.4 Option 1 re-affirms the decision to remove reference to BS 8414 and BR135 from the Technical Handbook and to notify BSD when used as an alternative approach. It was preferred by eleven respondents from all categories except research establishments/fire test houses.

4.2.5 A few respondents favoured this option as it was felt to be clearer and less complex than Options 2 and 3. It was stated that Option 1 provides clear height related standards and clear cladding performance options whereas Options 2 and 3 re-introduce separate guidance for buildings with a storey height over 18m. One respondent felt that Options 2 and 3 had some merits^[4] but also some adverse effects^[5] and, as a compromise, Option 1 was the best solution.

4.2.6 A few respondents also referred to BS 8414 and the negative perceptions and lack of confidence in the test. It was suggested that while BS 8414 provides an idea of how external wall materials might react in a fire, testing perfectly constructed samples does not reflect real world construction practices. Given the reservations about the application and efficacy of the test and classification methodologies, one respondent suggested there was an ongoing need for greater control over the use of BS 8414 and BR135 as an alternative approach at this time.

4.2.7 One respondent felt there was a need to "differentiate between any genuine technical pointers for improvements in the effectiveness of the test and classifications, and criticism of the test and classification that may have been encouraged/influenced by the alleged gaming of the test and classification rules". It was suggested that excluding system testing for reaction to fire was contrary to the wish for assemblies to be considered holistically rather than individual product testing and BS 8414 should be retained with any improvements to the test and classifications from the BSi review committees.

Option 2 – Managed Use of BS 8414 to Address Risk

4.2.8 Option 2 would cite reference to BS 8414 and BR135 in the Technical Handbook with tighter controls depending on the use and height of the building and was favoured by 17 respondents. The majority of respondents preferring this option were trade associations and individuals.

4.2.9 Many of the respondents supporting this option felt that there was a role for large scale system testing as it was the only way to establish whether the chosen components work together in their end use application. The following quotes illustrate the points raised:

"..it is important that we look at the testing of any building materials and their performance based on how they are used and perform in a built-up system. Test evidence can demonstrate combustible materials used in external wall systems can perform and meet the desired performance. Large scale testing should always be preferred over just specifying a non-combustible material".

"..the best way to achieve this [fire safe design] is through the use of large-scale system testing to establish both the performance of the materials to be used and the configuration in which they are to be used. Relying on a simple material classification based largely on small scale tests is unhelpful and does not guarantee a good level of fire safety, whatever the type or height of building involved. Instead, it could lead to a dangerous level of complacency and over-reliance on the fact that materials are classed as A1/A2 to compensate for poor building design and construction".

"..a ban on the use of combustible materials in external wall systems brings no guarantees that buildings will be safer. Instead a regime where whole systems are tested to an agreed methodology to give assured performance is the more appropriate approach. We would advocate the use of BS 8414/BR135 test as the best route to ensure such compliance. There is no advantage in testing individual materials in isolation, since their behaviour when combined with other products can be quite different".

4.2.10 A number of respondents provided links to articles or studies of large scale tests and real life case studies, including:

• The MHCLG^[6] tests^[7] in England on various façade systems in the large-scale BS 8414 test rig which provided an indication of what was acceptable and unacceptable performance and related compliance.
• A Tenos report^[8] which considers whether data from real fires suggests there is a need to review reliance on BS 8414/BR 135.
• Case studies^[9] analysing the performance of insulated panels.

4.2.11 Several respondents felt that this option enabled BS 8414 to be used but that it should be assessed/controlled by local authority building standards verifiers or third parties. It would allow the use of different materials in appropriate situations.

4.2.12 A few respondents clarified that they understood that Option 2 would still allow BS 8414 for buildings over 18m, but that this would be under the current managed approach via notification to BSD. This was supported as it provides an added layer of verification for high-risk buildings. It was also suggested (by a few respondents) that this position is clarified in the Technical Handbook with links to supplementary guidance for advice on the process.

Option 3 – Regulatory Ban

4.2.13 Option 3 proposes a regulatory ban (i.e. A1 or A2 only in regulation) for residential buildings with any storey more than 18m and was favoured by 23 respondents. Support for this option came from all categories except trade associations and research establishments/fire test houses.

4.2.14 Several respondents felt that this option removed any ambiguity and provided the greatest clarity for buildings over 18m. An outright ban was suggested to be the only way that safer cladding could be achieved. Without a ban one respondent stated that "there are too many things that can go wrong in relation to the specification of this type of material i.e. testing of the product, promotion of the product by industry, not actually knowing what the fire test data will show and confusion by the verifier as to what is actually allowed".

4.2.15 A few respondents emphasised some of the points from Part 2 (paragraphs 3.3.4 – 3.3.5 above) in terms of a regulatory ban being a stronger option and one respondent highlighted that Option 3 would allow a move towards consistency with England.

4.2.16 One respondent suggested that fire risk considerations should include a wide range of factors beyond height e.g. building use and the vulnerability of those using the building. Buildings over 11m were identified as being particularly challenging for evacuation and adequate fire-fighting. Related to the last point, a further respondent highlighted that ground access to the elevation of a building was not taken into account in the event of a fire and suggested that where a podium/lower level building abuts the elevation and prevents direct access for fire fighting and evacuation of occupants, the full elevation should be non-combustible A1 or A2 material. Although the regulations mention distance from boundary, they do not take account of the approximation of other buildings, limited access due to sloping land, rivers and other obstacles.

Option 4 – Any Alternative Proposal

4.2.17 Option 4 provided the opportunity for respondents to suggest any other alternative proposals and was supported by 19 respondents across all categories.

4.2.18 As expected from an option that asks for "any alternative proposal", there were many suggestions made. The analysis has tried to group the suggestions into similar themes.

Building Categories and Associated Risk

4.2.19 A few respondents proposed an alternative option which creates three distinct categories of buildings based on their particular risk. The alternative proposal was:

1. Domestic buildings and hotels

a. No taller than 11m: performance B-s1, d0 or better
b. Taller than 11m: performance A2-s1, d0 or better (with regulatory ban)

2. Entertainment and assembly buildings, residential care buildings and hospitals; and schools

a. Of any height: performance A2-s1, d0 or better (with regulatory ban)

3. All other buildings

a. No taller than 11m: performance B-s1, d0 or better
b. Taller than 11m: performance A2-s1, d0 or better (with regulatory ban)

4.2.20 This proposal was made on the basis that "BS 8414 and the associated BR135 classification criteria do not provide information that can be relied upon to either assure or inform the fire safety of real-life buildings. We therefore consider that BS 8414 testing and/or any likely, related FSE are unfit for use as a route to compliance for high-rise and other high-risk buildings".

4.2.21 A few respondents proposed that there is a statutory ban on the use of combustible products (products not classified A2-s1, d0 or better) in the external walls of all buildings taller than 11m (or having more than three storeys) and high-risk buildings such as hospitals, schools etc. of any height.

4.2.22 Reasons were provided to support this proposal including:

• Regulations being well within the fire-fighting capabilities rather than being at the outer limits of fire service capacity.
• The extended time it takes occupants to evacuate tall buildings, regardless of the mobility of the occupant.
• The vulnerability of high-risk buildings due to their size, function and the make-up and density of their occupants.

4.2.23 It was also suggested that this proposal should be amended to reduce the potentially fatal risk posed by the development of smoke and toxic gases during a façade fire. The proposal to ban the use of combustible products in the façade of high rise and other high-risk buildings substantially addresses concerns around both the spread of fire and the potential development of smoke and toxic fire gases.

Modifications of Other Options in the Consultation

4.2.24 Several respondents identified a number of proposals which could be considered as modifications of some of the options presented in Table 5 above. These are:

• Option 1 with regulatory ban on combustible cladding on domestic based buildings over 18m.
• Option 1 with a regulatory requirement for A1 or A2 performance for new buildings with sleeping accommodation on a storey exceeding 18m.
• Option 1 with a ban on FSE on high-rise buildings (top storey at a height greater than 18m) where there is a sleeping risk e.g. domestic buildings, hotels, residential care, hospitals.
• Option 1 where footnote 4 is removed or clarified^[10].

Technical Handbook Proposals

4.2.25 A few respondents suggested proposals which referenced the Technical Handbook:

• Return to the 1 October 2019 Technical Handbook where BS 8414/BR135 were acceptable as options anywhere. The respondent considered BS 8414 to be an aggressive test which allows comparison between one product and another in a repeatable and reproducible manner.
• Retain the current presentation in the Technical Handbook and add a statement "no FSE approach is permitted for any domestic building at a height of more than 18m".

Other Proposals

4.2.26 There were also some other proposals including:

• BS 8414 plus testing which includes combustibility of components and smoke and toxicity testing.
• Insist universally on Class A2-s1, d0 and suspend the acceptability of BS 8414 testing until its technical deficiencies have been resolved.

4.2.27 The latter point reflects the view that BS 8414 in both Parts 1 or 2 is not an acceptable alternative approach. A couple of studies were referenced to support this point^[11]. The respondent suggested the technical deficiencies of BS 8414 should be resolved by a programme of research across the four devolved nations (or Scotland if that were not acceptable to other administrations). Another respondent would also welcome parity across the devolved administrations and encourage co-operative research and a consistent approach for those applying the regulations across the UK.

4.2.28 One respondent felt there should be no allowance for alternative approaches that would justify the use of combustible products in external wall construction and suggested a phased proposal:

• Short-term: Retain Option 1 which still allows for a fire engineering approach for buildings with a storey more than 18m above ground.
• Medium-term: establish a technical advisory review group of special advisors who can comment/review fire safety engineering/ alternative approaches.
• Long-term: Invest in an independent scientific group to undertake/collaborate on research into long terms improvements in building safety.

Other Comments

4.2.29 A few respondents also stated that the terminology "FSE approach" is not clear. Respondents questioned what this approach would involve as they were not aware of any approach which would allow for a "fully fire engineered design" for an external wall. It was suggested that a fire engineer would require detailed understanding of material and system behaviour and experience of large-scale testing. As such it was felt that a fully fire engineered approach was not credible given the competence available in the fire engineering field.

4.2.30 It was also suggested that the footnote to FSE in Table 5 was counterproductive. All fire safety engineering work should be carried out by competent professional with appropriate skills, knowledge and experience, but the footnote suggests that other (i.e. not related to the performance of external walls) alternative fire engineering solutions would not need to be carried out by someone with appropriate skills, knowledge and experience.

4.3 General Points

4.3.1 One respondent made a point about Class F not being referred to in the Technical Handbook which means that these materials cannot be accepted in Scotland. The respondent was looking for clarity on why Class F is not included in the Technical Handbook.

4.3.2 One respondent had reservations about the use of reaction-to-fire classification systems such as BS EN 13501-1 as a tool for determining compliance/ non-compliance of construction products. It was suggested that BS EN 13501 is not designed or intended to be used in isolation for the purposes of determining fire risk/safety. It enables products to be ranked under specific small scale fire conditions and provides experts with information for further analysis. Large scale system tests (e.g. BS 8414) are the logical route for evaluating complete structures.