Textbook Technical Travesty
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Each FPRF project is guided by a technical panel that provides expertise with input from sponsors. The FPRF initiated Fire Hazards of Exterior Wall Assemblies Containing Combustible Components. They were concerned with the speed of a breach in compartmentation when fire can “roll-over” the exterior of buildings:
‘It is recognized from past experience that fire spread from floor to floor and over the fa?ade in buildings can be a catastrophic event. The regulatory and test-based methodology to address behaviour of fires in facades for different facade systems varies significantly for different countries.’
Nathan White and Michael Delichatsios, Document Number: EP142293, Fire Hazards of Exterior Wall Assemblies Containing Combustible Components - Final Report, Quincy, Massachusetts, Fire Protection Research Foundation, 1 June 2014, posted on
Phase I of this FPRF study was led by Nathan White and Michael Delichatsios.
Nathan White worked for the Commonwealth Scientific and Industrial Research Organisation, Victoria, Australia. Michael Delichatsios worked for the School of Built Environment, FireSERT, University of Ulster, Jordanstown, Northern Ireland until 2016. Between 2007 and 2010 he undertook grant funded research for the Engineering and Physical Sciences Research Council on Fa?ade Fires, prior to his work with CSIRO Australia. Delichatsios continues as the University of Ulster Fires and Material Flammability Associate, and maintains a website https://delifire.com.
Phase I work appears to have been underway in February 2013, but research work probably commenced earlier in 2012, and certainly stands on the earlier 2010 research by Michael Delichatsios for the ESPRC. There were notable external fires that an internationally focused Fire Engineer would have been aware of. The Phase I Final Report was freely published by NFPA for the FPRF in June 2014.
As White and Delichatsios explained the goal of Phase I was:
‘To compile information on typical fire scenarios which involve the exterior wall, compile relevant test methods and listing criteria as well as other approval/regulatory requirements for these systems, and to identify the knowledge gaps and the recommended fire scenarios and testing approach for possible future work… The USA, UK, and some European countries specify full-scale fa?ade testing but then permit exemptions for specific types of material based on small-scale fire testing.’
A possible Phase II was envisaged by the authors that would include experiments to evaluate performance of exterior walls with combustible materials.
Nathan White, Michael Delichatsios, Marty Ahrens and Amanda Kimball, Fire Hazards of Exterior Wall Assemblies Containing Combustible Components, London, EDP Sciences, 2013, posted on https://www.matec-conferences.org/articles/matecconf/pdf/2013/07/matecconf_isfsf13_02005.pdf
There appears not to have been any Phase 2 work published, to my knowledge.
In the Report Appendix B Regulations – Detailed Summaries there is Section B.3 UK Approved Document B on Page 105 to 106. Within that is B.3.1 Reaction to Fire Requirements for Exterior Wall Materials, in which the authors claimed:
‘UK National Class 0 materials are either non combustible when tested to BS 476‐4 or Limited combustibility when tested to BS 476‐11.’
This was incorrect at the time of the Report publication. Class 0 was only defined in Paragraph 13 of Appendix A of Approved Document Part B Volume 2 (2013). In 13a. Class 0 could mean Limited Combustibility to Table A7, or better, such as Non-Combustible to Table A6. However, Class 0 could also mean any Material or the Surface of a Composite Product that could pass the criteria in 13b. There is “or” between 13a. and 13b. clauses.
The clause 13b. definition of Class 0 (National) was achieved using a two-part small-scale test to BS 476: Part 7, for Class 1 surface spread of flame, and BS 476: Part 6, for fire propagation index (I) of less than 12 and sub-index (i1) of less than 6.
There were four ways to obtain Class 0 in Approved Document Part B Volume 2 (2013):
- Material - a. Limited Combustibility to Tests in Table A7
- Material - b. Tested to BS 476: Parts 7 and 6 as Paragraph 13
- Composite Product Surface - a. Limited Combustibility to Tests in Table A7
- Composite Product Surface - b. Tested to BS 476: Parts 7 and 6 as Paragraph 13
Having obtained Class 0 a homogeneous Material or a Composite Product could be used as the Surface of External Walls as Diagram 40 in Approved Document Part B Volume 2 (2013). This had long been the case, and I shall come back to Diagram 40.
Errors in an Appendix of a Report read by Fire Engineers may have not been too problematic since they might have known Class 0 meant something more combustible.
But the White and Delichatsios Report for the FPRF was more widely published by Springer in 2015 as part of their Briefs in Fire Series.
James A. Milke Editor, Nathan White and Michael Delichatsios, Springer Briefs in Fire - Fire Hazards of Exterior Wall Assemblies Containing Combustible Components, copyright the Fire Protection Research Foundation, New York, Springer-Verlag, 2015, available on https://www.springer.com/gp/book/9781493928972
Appendix B: Regulations – Detailed Summaries of their 2015 Textbook similarly considers UK Approved Document B on Page 118 to 120. On Page 119 they erroneously repeat:
The 2015 Textbook and the 2014 Phase I Report contain exactly the same content, though the Textbook has dropped the Section Report numbering. Section B.3 UK Approved Document B in the 2014 Phase I Report says the same thing as the Section titled UK Approved Document B in the 2015 Textbook:
‘The Building Regulations 2010 for England and Wales state the performance requirements with regards to fire safety. Approved Document B is a guidance documents (Sic) which states prescriptive requirements for fire safety which achieve compliance with the Building Regulations 2010. Alternative solutions supported by fire engineering analysis are permitted.’
That is true. The legal significance of the Approved Documents as guidance to compliance with the 2010 Building Regulations is given in Section 6 and 7 of the 1984 Building Act. In 2006 Approved Document Part B was divided into Volume 1 for Dwellinghouses and Volume 2 for all buildings other than Dwellinghouses. That arrangement was changed by 2019, after Grenfell Tower fire on 14 June 2017, but it is Approved Document Part B Volume 2 (2013) that matters. The Textbook and Report continue to consider Reaction to Fire Requirements for Exterior Wall Materials:
‘Approved Document B, Section 12 states external wall construction should either meet the limited combustibility requirements in Table B5 or should meet the performance requirements given in BRE Report BR 135 using full scale test data from BS 8414-1 or BS 8414-2.’
This is how that incorrect statement looks in print in the Textbook:
By Table B5 White and Delichatsios refer to their Table, repeated in the Textbook and the Report, with five Cases (a) to (e) that describe the same five cases of Overall Height and Distance from Relevant Boundary in Diagram 40 of ADBv2 (2013). As with Diagram 40 the authors transpose Class 0 (National) with Class B (European).
But White and Delichatsios incorrectly describe their Table B5 as meaning:
‘UK National Class 0 materials are either non combustible when tested to BS 476‐4 or Limited combustibility when tested to BS 476‐11.’
Not true.
The authors are correct that for Case (b), which is Diagram 40b., there are “No requirements”. Diagram 40 has that as “No provision”. That sounds like “anything-goes”, but of course all buildings must comply with 2010 Building Regulation, Schedule 1 Requirement B4-(1).
But White and Delichatsios should have known that BS EN 13501-1 Class B is in the combustible range. They should have known that it is possible for Class 0 (National) to be achieved by Products that could be Class B, C, or D when classified to BS EN 13501-1.
Moreover, White and Delichatsios should have known that Limited Combustibility when tested under BS 476-11 to specific criteria in Table A7 is transposed as Class A2 to BS EN 13501-1. Also, that Non-Combustible either classified under BS 476-4 or tested under BS 476-11 to specific criteria in Table A6 is transposed as Class A1 to BS EN 13501-1.
The authors also wrongly refer to Class 0 (National) or Class B (European) in Case (c) Assembly or Recreation buildings of less than 18m Overall Height and more than 1m Distance from the Relevant Building, which is Diagram 40c. Case (c) should be Class C (European), which the Key on Diagram 40 transposes to a fire propagation index (I) of less than 20 when tested to BS 476: Part 6.
White and Delichatsios give an inaccurate and unreliable summary of the Section 12 requirements in Approved Document B Volume 2 Part B (2013). They also claim their summary applies to the whole of the UK, when Scotland does not rely on the Approved Document that applied to England and Wales. Northern Ireland has another document.
Their 2014 Phase I Report and 2015 Textbook looks convincing. But only if the reader has not checked Section 12 requirements in Approved Document B Volume 2 Part B (2013). The precursor of Diagram 40, which originated in 2000, was Diagram 36 of 1991.
I have seen no correction by White and Delichatsios of either 2014 Phase I Report or 2015 Textbook in their Section titled “UK Approved Document B”. Neither have I checked whether all the summaries in that Appendix are correct for other countries.
It might be that White and Delichatsios do not know their understanding of Class 0 from the 2014 Report repeated in the 2015 Textbook is a technical travesty as published.
Would Nathan White and Michael Delichatsios stand by their Section titled “UK Approved Document B” today?
People listen to the NFPA. What White and Delichatsios have said in print might have influenced a constituency of Fire Engineers in 2014 and 2015, who in turn have advised various non-specialists. The misrepresentation of Class 0 may have had repercussions.
Has anyone advised the British Ministry for Housing, Communities and Local Government that White and Delichatsios were correct to say Class 0 = Limited Combustibility?
I would like to find out. They would also be wrong.
Just read that again...
White and Delichatsios incorrectly describe their Table B5 as meaning:
‘UK National Class 0 materials are either non combustible when tested to BS 476‐4 or Limited combustibility when tested to BS 476‐11.’
That is wrong, but they had all the means to correct the Report and Textbook at their disposal. In 6.1 Reaction to fire requirements they give another account of Approved Document B in Section 6.1.2 UK. Repeated in the Report on Page 41 and the Textbook on Page 50, with useful references consistent to both:
‘The UK Building Regulations and Approved Document B [78] requires either compliance with BRE Report BR135 using full scale fa?ade tests BS8414 part 1 [79] or part 2 [80], or requires materials to be noncombustible or limited combustibility materials based on either BS 476 part 6 [81] and part 11 [82] tests or Eurocode classification [83] (Class B‐s3,d2 or better). These requirements apply to buildings 18 m or more high or less than 1 m from a relevant boundary.’
By Reference [78] the authors are referring to ‘HM Government. (2013) "The Building Regulations 2010, Fire Safety Approved Document B". UK.’ They specifically refer to the 2013 Edition of Approved Document Part B, which has two Volumes, both now archived on the Government’s dedicated webpage, which address the law of the 2010 Building Regulations, Schedule 1, Part B. Documents current at their time of writing. In the next two References White and Delichatsios refer to:
79. BSI. (2002) "BS 8414‐1:2002 Fire performance of external cladding systems. Test methods for non‐loadbearing external cladding systems applied to the face of a building". UK.: British Standards Institute; 2002.
80. BSI. (2005) "BS 8414‐2:2005 Fire performance of external cladding systems Test method for non‐loadbearing external cladding systems fixed to and supported by a structural steel frame". UK.: British Standards Institute; 2005.
Approved Document Part B Volume 1 (2013), then concerned with Dwellinghouses, does not refer to either part of BS 8414. Those two “System” Test Methods are only referred to in Paragraph 12.5 of Approved Document Part B Volume 1 (2013) for Buildings other than Dwellinghouses. Then they are referred to as options to Paragraphs 12.6 to 12.9.
Of course, BS 8414-1 for non-loadbearing external cladding systems applied to the masonry face of a building and BS 8414-2 for non-loadbearing external cladding systems fixed to and supported by a structural steel frame were both revised in 2015 and amended in 2017, after White and Delichatsios had published.
Section 7.1.2 BS 8414 Part 1 and Part 2, on Pages 45 to 48 of the Report and Pages 57 to 59 of the Textbook, there is an account of the “System” tests and recognition that the pass/fail performance criteria is given in BRE Report BR135, which is Reference [17].
17. Colwell, S., Baker, T. (2013) "Fire performance of external thermal insulation for walls of multistorey buildings". Garston, Watford, UK: IHS BRE Press, Report No.: 978‐1‐84806‐234‐4 Document No.: BR 135.
The authors refer to the Third Edition of BRE 135 Fire performance of external thermal insulation for walls of multistorey buildings was published on 15 March 2013, because it was available at the time White and Delichatsios were writing. However, the Third Edition was not referred to in Paragraph 12.5 of ADBv2 (2013), which only referenced the 2003 Second Edition with the same title in Appendix H.
Differences between Parts 1 and 2 of BS 8414 are noted, with White and Delichatsios noting that the test simulates ‘… the scenario of flames emerging from a compartment fire via a window at the base of the wall.’ The wall above is blank, as is as the “L” shaped side wall, without other window and door openings, balconies or other attachments. It is an onerous test even without aspects of architectural fenestration as a “System”, though the omission of mechanical performance in the pass/fail criteria is a problem.
The 2014 Report of Fire Hazards of Exterior Wall Assemblies Containing Combustible Components was written before the dubious invention of “Desk Top Studies” by the Building Control Alliance in Technical Guidance Note 18 Use of Combustible Cladding Materials on Residential Buildings, now in its third version after Grenfell Tower fire. There is no mention of BCA TGN 18 in the 2015 Textbook, but that might not have alerted White and Delichatsios to the meaning of Paragraph 12.7 in ADBv2 (2013). Their Report and Textbook was certainly published before the development of BS 9414:2019 Fire performance of external cladding systems. The application of results from BS 8414-1 and BS 8414-2 tests. The wisdom of which requires separate attention.
But there is a simpler point. Since the use of BS 8414 “System” testing to pass/fail criteria in BR 135 was not mandatory it was important to appreciate that Class 0, required in Diagram 40, cited in Paragraph 12.6, was not onerous. It was easier to small scale Material or Product test for Class 0 than undertake a BS 8414 “System” test.
The “System” testing option was mostly used by those wanting to circumvent the onerous requirements for Limited Combustibility Insulation in Paragraph 12.7, affecting buildings with Storey Heights over 18m. Many Cladding Materials and Products that were not Limited Combustibility to Class 0 Paragraph 13a. could otherwise achieve Class 0 Paragraph 13b. of ADBv2 (2013). The optional “System” testing mattered more to the manufacturers of Insulation because of Paragraph 12.7 than it did to the manufacturers of Cladding concerned far more with Class 0, Diagram 40 and Paragraph 12.6.
White and Delichatsios seem not to have appreciated that the Paragraph 13b. definition of Class 0 based in BS 476 Parts 6 and 7 undermined the option of “System” testing. But they also seemed blind to the need for BS 476 Part 7, when they say:
‘… requires materials to be noncombustible or limited combustibility materials based on either BS 476 part 6 [81] and part 11 [82] tests’
81. BSI. (1989) "BS 476‐6:1989+A1:2009 Fire tests on building materials and structures Method of test for fire propagation for products ". UK.: British Standards Institute; 1989.
82. BSI. (1982) "BS 476‐11:1982 Fire tests on building materials and structures Method for assessing the heat emission from building materials ". UK.: British Standards Institute; 1982.
It is true that BS 476 Part 11, which was last revised in 1982, is referred to in Table A6 for Non-Combustible Materials and Products and Table A7 for Limited Combustibility. But here White and Delichatsios do not mention BS 476 Part 4, which was last revised in 1970, as a test for Non-Combustibility. They refer to BS 476 Part 4 beneath Table B5 of their Report and Textbook. Instead in Section 6.1.2 UK they seem more aware of BS 476 Part 6, which was last revised in 1989 and amended in 2009. But BS 476 Part 6 is about Fire Propagation. It is used to achieve the second set of criteria in Paragraph 13b. in Appendix A of ADBv2 (2013) as the definition of Class 0.
BS 476 Part 6 is the test method used to determine on small scale Specimens of a Material or Product a Fire Propagation Index of (I) of not more than 12 and a Sub-Index of (i1) of not more than 6. White and Delichatsios seem to know about BS 476 Part 6 but do not explain its significance in Paragraph 13b. as the alternative to Limited Combustibility in 13a.
The Class 0 definition in Paragraph 13b. additionally requires Class 1. That is the lowest Surface Spread of Flame classification achieved using BS 476 Part 7, which ranges from Class 1 to Class 4. BS 476 Part 7, also using small scale Specimens of the same Material or Product being tested under BS 476 Part 6 to obtain a Class 0, and which was last revised in 1997. Class 0 requires two test methods. This meaning of Paragraph 13b. criteria was not explained in ADBv2 (2013), but it was not hard to ascertain.
Indeed under 7.4.4 British Classification Tests, on Page 67 of the Report and Page 83 of the Textbook, there is 7.4.4.1 BS 476 Part 6, again with Reference [81], but also 7.4.4.2 BS 476 Part 7, with Reference [136].
136. BSI. (1997) "BS 476‐7:1997 Fire tests on building materials and structures Method of test to determine the classification of the surface spread of flame of products ". UK.: British Standards Institute; 1997.
White and Delichatsios did know about BS 476 Part 7 Class 1, but had not associated it with the ADBv2 (2013) Paragraph 13b. definition of Class 0. That is a blindness.
In the prior Section 7.4.3 Euroclass Tests, on Pages 66 to 67 of the Report and Pages 80 to 83 of the Textbook, there is an account of BS EN 13501-1 as Reference [83].
83. CEN. (2007) "EN13501‐1:2007: Fire classification of construction products and building elements‐Part1: Classification using data from reaction to fire tests ". European Committee for Standardization; 2007.
BS EN 13501-1 was revised in 2018, and prior to that had been amended in 2009 to the 2007 Revision. White and Delichatsios clearly state in Section 7.4.3 Euroclass Tests that Class B Products are Combustible. In Table B5 White and Delichatsios should then have known that BS EN 13501-1 Class B is in the combustible range. They should have known that it is possible for Class 0 (National) to be achieved by Products that could be Class B, C, or D (European) when classified to BS EN 13501-1.
Of course, it is not possible to equate Class 0 to criteria in BS 476 Parts 6 and 7 to the Classification of B‐s3,d2 or better that White and Delichatsios refer to in Section 6.1.2 UK and Table B5 of their 2015 Report and 2015 Textbook. Diagram 40 in ADBv2 (2013) warns against equating Class 0 (National) with Class B (European) but then makes exactly that transposition. That should have alerted White and Delichatsios to the errors in Section 6.1.2 UK and Table B5 of their 2015 Report and 2015 Textbook.
All this is such a pity, because Fire Hazards of Exterior Wall Assemblies Containing Combustible Components is an otherwise instructive read.
Technical Designer
3 年Nathan White published an Errata and Addendum to his FPRF initiated?"Fire Hazards of Exterior Wall Assemblies Containing Combustible Components" via the NFPA on 14 December 2020. No comment to my knowledge on the Errata in particular was received from Michael Delichatsios, Nathan White's co-author in 2014. "The Errata primarily relate to an incorrect summary of Class 0 for England and Wales as defined by Approved Document Part B Volume 2 (2013)." "It is noted that the 2013 Approved Document B Volume 2 reaction to fire provisions for external surfaces are less stringent than for insulation." The authors had previously thought Cladding had to be Limited Combustibility, when at least Nathan White now recognises, as do the NFPA, that only Insulation had to be Limited Combustibility as Paragraph 12.7 in ADBv2 (2013) as written. Moreover they state that: "Approved Document B Volume 2 (2013) does not appear to clarify if the combustible core of an Aluminium Composite Panel (ACP) should be regulated as an insulation material or as “composite product” which would only require the external surface to be exposed when tested in BS 476:Part 7 and BS 476:Part 6, without testing the exposed core material." This of course relates to the Ministry lie in Footnote 4. of Advice Note 1. on 30 June 2017, which insisted that Cladding Product, and specifically Aluminium Composite Material (ACM) was included in Paragraph 12.7. The published Approved Document had never said that. The hesitant language of the Errata is at least a clarification that the Ministry has to substantiate Footnote 4. It can't. It lied. https://www.nfpa.org/News-and-Research/Data-research-and-tools/Building-and-Life-Safety/Fire-Hazards-of-Exterior-Wall-Assemblies-Containing-Combustible-Components Errata: https://www.nfpa.org/-/media/Files/News-and-Research/Fire-statistics-and-reports/Errata/ErrataFireHazardsOfExteriorWallAssembliesContainingCombustibleComponents.ashx Addendum: https://www.nfpa.org/-/media/Files/News-and-Research/Fire-statistics-and-reports/Building-and-life-safety/AddendumFireHazardsOfExteriorWallAssembliesContainingCombustibleComponents.ashx It is expected that Springer will also publish an Errata and perhaps an Addendum.
Professor of Fire Science | Science, Heat Transfer, Engineering
3 年Nice in-depth study of this report. I believe this review was the very first of its kind. I value that. I think that NFPA is producing an erratum to correct for they issues you have found Ian. Well done to NFPA as well for being so responsive.
FIFSM
4 年I thought BRE 135 document highlighted this potential fire spread much earlier that NFPA or other post 2000 reports mentioned here ?
Technical Designer
4 年The NFPA's Amanda Kimball has confirmed that the Errata produced by Nathan White and in the process of review will shortly be published on "Fire Hazards of Exterior Wall Assemblies Containing Combustible Components". I have no idea if Michael Delichatsios has had a hand in the Errata, but I hope so. Both authors need to make their correction about Approved Document Part B Volume 2 (2013) in the UK, pre-Grenfell Tower fire. https://www.dhirubhai.net/pulse/textbook-technical-travesty-ian-abley/ Thanks to Doug Evans. https://www.dhirubhai.net/posts/douglasevansfsfpe_the-persistent-problem-of-facade-fires-activity-6668695651343331329-I7no The sooner the better, and in due course...
Technical Designer
4 年I'm told by author Nathan White and Birgitte Messerschmidt at the NFPA that a correction is "in the works". Looking forward to reading it.