Grenfell Tower Inquiry: Phase 2 Report · 2024
Chapter 57: Cavity barriers
Chapter 57: Cavity barriers
Introduction
¶57.1 In this chapter we examine the use of cavity barriers on the Grenfell Tower refurbishment project, including the formulation of a cavity barrier strategy by Studio E and Harley and the installation of the cavity barriers themselves by Osborne Berry. We have concluded that none of the construction professionals gave adequate consideration to the use of cavity barriers at any stage of the design process. Moreover, it was also an aspect of the design that received scant attention from building control, either in the course of reviewing the drawings or during inspections on site. Although there were a number of detailed discussions between the design professionals about cavity barriers, none of them paid sufficient attention to the need for an overall strategy or gave sufficient consideration to the purpose of cavity barriers in preventing the spread of fire. As a result, cavity barriers were not installed in the correct positions and were entirely missing around the windows. In addition, many of the cavity barriers which were fitted were poorly installed.
¶57.2 Although the failure to ensure that cavity barriers were properly installed within the cladding probably had little effect on the ultimate development of the fire,1851 Grenfell Tower Inquiry Phase 1 Report, Chapter 23, paragraph 23.60. it demonstrates a worrying lack of attention to fire safety which we think it is important to record as part of our analysis of the events which led to the tragedy. Moreover, it is possible that the absence of cavity barriers around the windows played a part in enabling the fire to escape from Flat 16 and gain unrestricted access to the combustible insulation and ACM PE cassettes.1852 Grenfell Tower Inquiry Phase 1 Report, Chapter 22, paragraph 22.40. For those reasons we explain below how it came about that the cavity barriers at Grenfell Tower were so poorly designed and installed.
¶57.3 Two types of cavity barrier were used in the external wall at Grenfell Tower. The horizontal cavity barriers were "open state", meaning that they were designed to be installed with a gap between the face of the barrier and the rainscreen to allow the passage of air and moisture. On the edge of the barrier facing the panels was an intumescent strip that expanded to close the gap when exposed to heat. The vertical cavity barriers were described as "full fill", meaning that they consisted of a solid piece of material spanning the entire cavity, thus forming a permanent vertical barrier against the horizontal spread of fire.
Consideration of Cavity Barriers at or before RIBA Stage D
¶57.4 Although Studio E began talking to building control at an early stage in the project, there was no discussion about the cladding or the requirement for the installation of cavity barriers within the facade.1853 The first meeting with building control took place on 7 November 2012. Adrian Jess' email notes of that meeting dated 7 November 2012 {SEA00006526}; Sounes {Day21/132:23}-{Day21/133:3}; there was a further meeting on 17 September 2013 but, again, there was no focus on cladding or cavity barriers: Sounes {Day21/135:1-25}; Sounes {SEA00014273/129} page 129. There was no mention of cavity barriers or of the need to maintain compartmentation in Studio E's Stage D report1854 {SEA00008054}. dated 20 August 2013,1855 Sounes {Day21/76:16-19}. nor was there any reference to the installation of cavity barriers in any version of Exova's Outline Fire Safety Strategy, including Issue 3 dated 7 November 2013.1856 See Chapter 54.
176Tender documentation: August 2013 – January 2014
¶57.5 The first person at Studio E to give any serious consideration to the need for cavity barriers was Tomas Rek. He had been asked to develop the NBS Specification and tender drawings to send to potential contractors.1857 Rek {Day12/11:17-20}. Part of that task involved revising the existing tender drawings to show the location of cavity barriers.1858 Rek {Day12/98:4-6}.
¶57.6 Although some preliminary design work on cavity barriers had been undertaken before September 2013, it was limited. Mr Rek could not recall the extent of the work that had already been done but said that the NBS Specification had not been completely blank when he started working on it.1859 Rek {Day12/12:7-17}. Mr Sounes' belief was that Studio E had done some work on cavity barriers between December 2012 and June 2013.1860 Sounes {Day21/77:5-21}.
¶57.7 At the time of his work on the tender documents, Tomas Rek was aware of Diagram 33 in Approved Document B, which set out the requirements for cavity barriers in specified locations,1861 Rek {Day12/94:7-15}. but could not remember whether he had reminded himself of it at the time.1862 Rek {Day12/95:6-7}. Although Bruce Sounes, who was supervising him, was aware of the guidance in Approved Document B he did not review Diagram 33 at any stage.1863 Sounes {Day21/70:22}-{Day21/71:3}; {Day21/71:16}-{Day21/72:3}.
¶57.8 The tender pack which Studio E prepared to send to potential contractors included several drawings depicting the "Employer's Requirements", which set out the basic principles of the design. Between 24 and 25 September 2013 Mr Rek revised one of the drawings1864 Studio E's drawing entitled "Employer's Requirements - Proposed Typical Bay Plans, Section & Elevation"; Rek {Day12/107:20}-{Day12/108:5} to show cavity barriers and their locations. The original version of the drawing (dated 24 September 20131865 {SEA00002155} with Studio E reference 1279 (06) 110 Rev 00.) contained a label which read, "Provision of cavity fire barrier TBC". The version produced by Tomas Rek the following day, 25 September 2013,1866 {SEA00002163} with the same Studio E reference. contained some information about the location of cavity barriers. In particular: a. Hatching had been applied to the Proposed Plan and Proposed Section drawings showing where cavity barriers were to be placed.
¶b. Cavity barriers were shown along the line of compartment floors, in particular, i. The sections entitled "Proposed Plan – Cill Level" and "Proposed Plan – Window
177Level" had annotations reading, "Cavity fire barrier in line with compartment wall structure. Leave no gap to cladding."
ii. The section entitled "Proposed Section – Typical Bay" contained annotations reading, "Ensure horizontal and vertical cavity barriers meet tightly" and "Cavity fire barrier in line with compartment floor structure. Leave max 25mm gap to cladding for ventilation and drainage."
¶c. Cavity barriers were not shown around the windows. Mr Crawford accepted that Studio E's cavity barrier strategy did not require the installation of cavity barriers around the windows.1867 Crawford {Day10/192:1-5}.
¶57.9 Although the drawing contained some unlabelled hatching next to the window reveal, Mr Rek was not sure whether he had intended to specify a cavity barrier in that position; the hatching was not labelled as such (unlike other cavity barriers shown in the drawing) and he accepted that a subcontractor looking at the drawing would not have interpreted the hatching as a cavity barrier in the absence of some other indication that that was intended.1868 Rek {SEA00014278/30} page 30, paragraph 126; Rek {Day12/110:2-4}; {Day12/112:1}-{Day12/113:2}. In our view, on a fair reading of the drawing it did not clearly indicate a cavity barrier in that position.
¶57.10 Neither Mr Sounes nor Mr Rek could remember what had been the source of the information about the location of cavity barriers that had been used to create those drawings.1869 Sounes {Day21/83:8}-{Day21/84:6}; Rek {Day12/100:14-23}. Mr Rek was unable to recall any discussions when he revised the drawings1870 Rek {Day12/108:19-21}. but said that it had been his practice to discuss drawings with Mr Sounes when he made any material changes.1871 Rek {Day12/108:7-10}. Mr Sounes recalled Mr Rek's having told him that he had consulted others who had specialist knowledge about such things, but he could not remember the names of any particular individuals or companies he had contacted.1872 Sounes {Day 21/82:17}-{Day21/83:3}; {Day21/73:20}-{Day21/74:6}. There is no record of any such conversations and we think it unlikely that any took place.1873 Sounes {Day21/83:4-7}.
¶57.11 The drawings that Tomas Rek revised were at 1:20 scale and he was not asked to produce more detailed drawings at a 1:5 scale. He accepted in his evidence that drawings on a 1:5 scale would have clearly shown where cavity barriers were to be located.1874 Rek {Day12/115:7-15}.
¶57.12 On 1 November 2013, Tomas Rek sent an email to Terence Ashton of Exova asking him to confirm that the rainscreen cavity barriers should have 60 minutes' fire resistance to match that of the compartmentation.1875 {EXO00000586/1}. He did not ask Mr Ashton where cavity barriers ought to be placed or send him any drawings showing where he proposed to place them. A few days later Mr Ashton replied, saying that cavity barriers needed to have only 30 minutes' fire resistance.1876 {EXO00000586/1} dated 4 November 2013. Mr Rek did not recall having spoken to Mr Ashton about the positioning of cavity barriers1877 Rek {Day12/105:3-7}. and although Mr Sounes thought that the guidance in Section 9 of Approved Document B was unclear, he did not seek advice or assistance from Exova.1878 Sounes {Day21/81:2-20}.
¶57.13 At no point did Studio E produce detailed drawings of typical elevations or sections for use at tender stage showing precisely where cavity barriers were to be positioned.1879 Sounes {Day21/84:20-24}.
178¶57.14 The tender drawings were accompanied by the NBS Specification, which contained details of the types of cavity barriers to be installed in the horizontal and vertical positions.1880 In section P10 "Sundry insulation/ proofing work" at Clause 435. All three versions of the NBS Specification (21 November 2013 {SEA00000152/263}, 29 November 2013 {RYD00001712/245} and 30 January 2014 {SEA00000169/246}) contained the same clause 435 in Section P10 in respect of ventilated cavity barriers. Although there was an inconsistency in the specification, one part requiring 60 minutes' integrity and insulation and another only 30 minutes' integrity and insulation,1881 The products specified were "Lamatherm CW-RSH60" and "Lamatherm CW-RSV60" which could have been interpreted as a reference to 60 minutes' integrity. However, the clause also stated: "Fire resistance rating: 30/30 to BS 476, Part 20:1987 and BS EN 1366-4:2006. See also the witness statement of Stephen Swales (Siderise) which sets out the coding conventions for Siderise cavity barriers at the time. Swales {SIL00000306/9-10} pages 9-10, paragraph 38. both exceeded the minimum requirement in Approved Document B of 30 minutes' integrity and 15 minutes' insulation.1882 Table A1 of Approved Document B: {CLG00000224/125}.
Studio E drawing design after tender
¶57.15 Studio E did not revise its drawings in relation to cavity barriers after the invitation to tender had been issued on 29 November 20131883 This was done by email to Studio E on 29 November 2013 {SEA00010081}. Five main contractors were invited to tender: Mullaley, Durkan, Keepmoat, Rydon, and Wates. and as a result Harley based its design for the facade on the tender drawings.1884 Lamb {HAR00010419/5} page 5, paragraph 22. Studio E continued to be involved in the project until Harley began its detailed design work in late August 2014,1885 Lamb {HAR00010419/6} page 6, paragraphs 22-24. but there is no evidence that it carried out any further work on the cavity barrier strategy during that time.
Harley's initial design
¶57.16 Harley's design work started in earnest after Kevin Lamb was appointed on 12 August 2014.1886 {HAR00010418}. Mr Lamb said that he had based his work on the plans, sections and elevations produced by Studio E for the key aspects of the external facade.1887 Lamb {HAR00010419/5} page 5, paragraph 20. He also made use of a set of preliminary drawings of a typical window detail prepared by Samuel Anketell-Jones and Ray Bailey before his involvement. They did not show any cavity barriers.1888 {HAR00010432}.
¶57.17 Kevin Lamb accepted that the requirements of the NBS Specification relating to cavity barriers took precedence over the tender drawings.1889 Lamb {Day38/123:22}-{Day38/124:21}. The NBS Specification required compliance with Approved Document B and the Standard for Systemised Building Envelopes published by the Centre for Window and Cladding Technology (CWCT).1890 Dated September 2008 {CWCT0000046}. Both documents clearly called for cavity barriers around windows.1891 Approved Document B at {CLG00000224/83} paragraph 9.3; {CLG00000224/96} paragraph 12.8; the CWCT Standard {CWCT0000046/14} section 6.4.4.2 under the heading "Cavities in rainscreen walls".
¶57.18 On 22 August 2014, Kevin Lamb produced some preliminary drawings to establish the basic principles of the design which he sent to Simon Lawrence of Rydon and copied to Studio E and Daniel Anketell-Jones of Harley.1892 {HAR00010426}. Those drawings did not indicate where cavity barriers would be placed within the facade.1893 {RYD00016100}. Neil Crawford commented on the drawings on 27 August 20141894 {HAR00010423/2}. but did not draw attention to the absence of cavity barriers.1895 Crawford {Day10/185:2-5}. He could not recall having raised the absence of cavity barriers with Harley at that time.1896 Crawford {Day10/185:11-14}.
179¶57.19 Mr Crawford provided further comments on Harley's drawings on 3 September 2014 following a design team meeting1897 {HAR00010413}. but did not refer to the absence of cavity barriers.1898 {HAR00010423/2}; {HAR00012086}. On 12 September 2014, he confirmed that he had no further comments to make.1899 {HAR00010423/1}.
The Request for Information
¶57.20 On 17 September 2014, for reasons which remain unclear, Daniel Anketell-Jones sent a formal Request for Further Information to Rydon and Studio E, with a copy to Kevin Lamb, seeking instructions on the provision of horizontal cavity barriers within the area of the cladding.1900 Email dated 17 September 2014 {HAR00003638/4}; RFI attachment {EXO00001291}. He suggested that cavity barriers were required at every floor level on the vertical columns, but not in the area between the windows because there was no "chimney" effect there so the cladding would not exacerbate the spread of fire.
¶57.21 On 18 September 2014 Mr Crawford sent the request on to Mr Ashton at Exova asking for his comments.1901 {HAR00003638/4}. In response, Mr Ashton asked for a set of drawings, which were provided to him by Mr Crawford, who told him that they represented an attempt to establish the basic approach.1902 Email: {HAR00003638/3}; Studio E Drawings attached: {EXO00000710}; {EXO00000711}; {EXO00000712}; Harley Drawing attached: {EXO00000713}. They included a drawing produced by Harley, which did not show any cavity barriers,1903 {EXO00000713} Title: Typical Bay Levels 1 to 20 West Elevation Reference: C1059-200, drafted by Kevin Lamb and dated 20 August 2014; Crawford {Day10/82:13-20}. and drawings produced by Studio E,1904 {EXO00000710}; {EXO00000711}; {EXO00000712}. which showed cavity barriers around each flat but not around the window frames.
¶57.22 Mr Ashton's response was that if the insulation in the cavities was combustible it would be necessary to provide cavity barriers in order to prevent fire from spreading from one flat to the flat above. That advice was wrong, however, because cavity barriers were required regardless of the nature of the insulation.1905 Ashton {Day18/39:1-18}. Mr Anketell-Jones did not ask Mr Ashton why cavity barriers were required only if the insulation was combustible1906 Anketell-Jones {Day36/162:4-8}. and Mr Ashton did not comment on the absence of cavity barriers from Harley's or Studio E's drawings.
¶57.23 Later that same day, Mr Crawford sent Mr Ashton's response on to Mr Anketell-Jones with copies to Simon Lawrence, Simon O'Connor and Kevin Lamb.1907 {HAR00003638/2}. In response, Mr Anketell- Jones asked Mr Ashton to confirm his own view that since the insulation was rated Class 0, a "fire barrier" was not required between the windows and attached the datasheet for Celotex RS5000.1908 {HAR00012104}. Simon Lawrence did not pay much attention to the exchange because he expected Harley to carry out the design work and Studio E to check it before it was referred to building control1909 Lawrence {Day24/124:4-13}. for approval.1910 Lawrence {Day24/123:17-22}.
180¶57.24 Mr Ashton replied to Mr Anketell-Jones on 18 September 2014 without having looked at the datasheet.1911 Ashton {Day18/46:15-23}; {Day18/47:3-19}; {Day18/49:1-8}; {Day18/55:6-8}. He pointed out that a material that had a Class 0 rating was not necessarily non-combustible, although the reverse was invariably true. He said that it was not clear from the information he had been given whether there was a continuous cavity from top to bottom in any part of the cladding, thereby inviting him to provide further information.1912 {HAR00003638}. Mr Anketell-Jones sent Mr Ashton's email on to Mr Crawford the same day asking him for his view on Mr Ashton's comments about combustibility and continuous cavity paths.
¶57.25 The matter was allowed to rest there, however. Mr Ashton did not chase Mr Anketell-Jones for further information1913 Ashton {Day18/59:5-22}. and Mr Anketell-Jones did not pursue the matter with either Mr Crawford or Mr Ashton.1914 Anketell-Jones {Day36/167:22-24}.
Harley's work on the design of the windows: September 2014–March 2015
¶57.26 On 22 September 2014 Kevin Lamb sent Simon Lawrence a set of drawings for final approval reflecting comments made by Studio E at their previous meeting.1915 {SEA00011759}; Attached drawings at {RYD00018436}. None of them contained any details of cavity barriers.1916 {RYD00000431}. Although both Bruce Sounes1917 On 22 September 2014 {RYD00018537}. and Neil Crawford1918 On 24 September 2014 {RYD00018687}. both commented on the design of the windows, neither of them referred to the absence of cavity barriers around the windows. Mr Lamb expected details of the cavity barriers to be provided at a later date,1919 Lamb {Day38/89:4-7}. so he could not have considered the drawings to be final.
¶57.27 Mr Lamb issued a revised set of drawings on 14 January 2015,1920 {RYD00027692}; Attached drawings at {RYD00027693}; {RYD00027694}; {RYD00027695}; {RYD00027696}; {RYD00027697}; {RYD00027698}; {RYD00027699}; {RYD00027700}; {RYD00027701}; {RYD00027702}; {RYD00027703}; {RYD00027704}. all of which were marked as "Approved for Construction" although they did not show any cavity barriers. No one in the design team at Harley noticed the omission, possibly because Harley did not have a fully effective procedure for reviewing the status or progress of the design at particular points in the life of the project or for reviewing the design as it developed. Mr Lamb was not directly supervised1921 Anketell-Jones {Day36/176:4-23}. and he confirmed that no one had checked the revised drawings before they had been issued.1922 Lamb {Day38/90:6-12}.
181¶57.28 Despite the fact that the drawings were marked as having been approved for construction, on 16 January 2015 Mr Crawford responded with his comments.1923 {SEA00012531}; Annotated drawings at {SEA00003040}. They had been marked using Studio E's stamp as being either "Status A: Conforms to Design Intent" or "Status B: Conforms to Design Intent subject to incorporation of comments. Revise and resubmit for Category A status." No mention was made of cavity barriers.1924 Lamb {Day38/92:5-7}; Crawford {Day10/196:13}-{Day10/197:2}; {Day10/197:15-22}. Although Mr Lamb said that there had been discussions within the design team in relation to cavity barriers, he was certain that he had never discussed the detailed guidance in Approved Document B on where cavity barriers ought to be placed to comply with functional requirement B4.1925 Lamb {Day38/92:16}-{Day38/93:9}.
The fire at Taplow House
¶57.29 On 16 January 2012 a fire occurred in a flat on floor 17 of Taplow House, part of the Chalcots Estate in Camden.1926 Ray Bailey {HAR00010184/4} page 4, paragraph 15. The facade had been installed by Rydon and Harley using mineral wool insulation (probably Rockwool) and riveted Reynobond PE 55 rainscreen panels.1927 Ray Bailey {Day33/141:13-20}; {Day33/60:15-25}. Timothy Lovell of Harley inspected the building on 17 January 2012 and prepared an initial incident report, which was distributed to Ray Bailey and Daniel Anketell- Jones, amongst others.1928 {HAR00010169}. In it he recorded that, despite the fire and the amount of flammable items in the flat, the fire breaks had still been intact and had prevented the fire spreading between flats.1929 {HAR00010169/4}. Above that paragraph was a photograph showing a "fire break" at the head of the window, although Ray Bailey thought that it was in fact a firestop rather than a cavity barrier.1930 Ray Bailey {Day33/143:20-25}.
¶57.30 Mr Lovell made a further inspection on 18 January 2012 and set out his findings in a report dated 23 January 2012, copies of which were given to Stephen Blake at Rydon, Ray Bailey and Daniel Anketell-Jones, amongst others.1931 {CEP000003223}. The report again drew attention to the containment of the fire by "fire breaks" located at the head and sill of each window.1932 {CEP000003223/2-3}. Mr Anketell-Jones said that he had not been aware that "fire breaks" had played an important part in preventing the spread of fire and did not recall anyone at Harley discussing the importance of cavity barriers or firestopping around windows following that fire.1933 Anketell-Jones {Day35/149:1-8}. He confirmed that, when Harley came to design the facade of Grenfell Tower, the fire at Taplow House appears to have been forgotten.1934 Anketell-Jones {Day35/149:14-19}. Ray Bailey accepted that Harley's failure to implement the lessons from Taplow House was an error.1935 Ray Bailey {Day33/146:11-16}.
¶57.31 Stephen Blake of Rydon agreed that the use of cavity barriers around the windows of Taplow House had been a critical factor in preventing the spread of fire.1936 Blake {Day29/126:25}-{Day29/127:8}. He also agreed that he had first-hand knowledge of the importance of cavity barriers around windows,1937 Blake {Day29/127:17-19}. but despite that, he did not think it necessary to check with Studio E or Harley that proper cavity barriers had been included in their designs.1938 Blake {Day29/130:3-10}.
182¶57.32 The experience at Taplow House ought to have made clear to Harley (and to a lesser extent, Rydon) the importance of installing fire protection measures around the windows at Grenfell Tower. But Harley and Rydon did not bear those lessons in mind when considering the design in the areas surrounding the windows of Grenfell Tower. Ray Bailey accepted that it was a mistake not to have done so.1939 Ray Bailey {Day33/146:11-16}.
March 2015 emails
¶57.33 On 3 March 2015, Kevin Lamb sent a set of drawings to Rydon which had been revised to include cavity barriers.1940 Email {SEA00012850} sent to Simon Lawrence, copying Neil Crawford, Bruce Sounes, Daniel Anketell-Jones, Mark Stapley, Mr Robert Maxwell and Mr Ben Bailey. Drawings attached: Specification Notes C1059-100 Rev A {SEA00000256}; Drawing Register {SEA00012855}; Typical Bay Levels 1 to 20 South Elevation C1059-202 Rev C {SEA00012851}; Typical Bay Levels 1 to 20 West/East Elevation C1059-201 Rev D {SEA00003155}; Typical Bay Levels 1 to 20 East & West Elevation C1059-200 Rev I {SEA00003156}; Jamb Joint Upper Levels and Typical Joint Upper Levels C1059-305 Rev C {SEA00012856}; and, Window Head Upper Levels C1059-301 Rev E {SEA00012857}. He also sent copies to various persons in Harley. Mr Lamb said that he had included cavity barriers in the drawings because the cladding was going to be installed soon and so completing the design had become urgent.1941 Lamb {Day38/97:5-14}. Mr Lamb had looked at some industry guidance in relation to cavity barriers,1942 Lamb {HAR00010419/13} page 13, paragraph 50 gives the following list of the guidance Mr Lamb recalls consulting: Approved Document B, the Centre for Window and Cladding Technology ("CWCT") Standard for Systemised Building Envelopes Part 6 – Fire Performance, the CWCT Technical Note 73 and Siderise technical literature. but only to find out what rating was required, rather than to where they should be placed.1943 Drawings 200 {SEA00003156}; 201 {SEA00003155}; 202 {SEA00012851}; 301 {SEA00012857}; 305 {SEA00012856} Lamb {HAR00010419/13} page 13, paragraph 50; Lamb {Day38/99:3-8}.
¶57.34 Each of the drawings bore a revision date of 3 March 2015. Cavity barriers were marked as broken lines surrounding compartments and were labelled as "firebreaks". Mr Lamb said that "firebreak" was a generic term and that at the time of his work on the Grenfell Tower refurbishment project he would probably not have used the term "cavity barrier".1944 Lamb {Day38/100:8-12}. There were no cavity barriers shown immediately around the heads, sills or jambs of the windows.1945 Lamb {Day38/101:7-10}. Mr Lamb's explanation for their absence was that Studio E's drawings and Harley's instructions were to show cavity barriers only around the compartment.1946 Lamb {Day38/102:4-10}. The positioning of horizontal cavity barriers above the windows and supposedly in line with compartment floors was different from that which had been shown at the tender stage by Studio E.1947 The Employer's Requirements - Proposed Typical Bay Plans, Section & Elevation drawing {SEA00002163}. Studio E's drawings showed a cavity barrier immediately at the head of the window, whereas Harley's drawings showed it at some distance from the head of the window in the spandrel section.1948 Lamb {Day38/102:11-21}. That change was never expressly brought to Studio E's attention, despite Mr Lamb's acceptance that it was a development of the design made by Harley.1949 Lamb {Day38/110:15-20}; {Day38/111:13-15}.
¶57.35 The detail of the window head1950 Harley drawing 301 {RYD00000220}. showed a horizontal cavity barrier at some remove from the window frame, marked with honeycomb hatching and labelled "Firebreak cut around cladding rails. All joints taped on top face." When he gave evidence Mr Lamb suggested that the cavity barrier was positioned above the head of the window because the window hung down below the structure and the concrete did not provide a flat surface.1951 Lamb {Day38/104:9-23}. However, he conceded that something would have to be added if the cavity barrier were positioned above the head of the window as he had suggested.1952 Lamb {Day38/106:12-18}. Mr Lamb never considered how the integrity of the horizontal cavity barrier would be maintained if it were cut to fit around the vertical cladding rail1953 Lamb {Day38/112:8-13}. and he gave no thought to whether the gaps created by the cladding rails should be filled to maintain the integrity of the cavity barriers.1954 Lamb {Day38/151:7-17}; {Day38/152:6-8}.
183¶57.36 On 3 March 2015, shortly after he had sent the drawings to the design team,1955 Lamb's email to the design team {SEA00012850} was timed at 12:58. His email to Carrick was at 13:06. Kevin Lamb sent an email to Barnaby Carrick, the Technical Applications Engineer at Siderise seeking his advice on using the horizontal barriers in a cavity which was wider than the maximum dimension shown in Siderise's literature.1956 {HAR00004013} the cavity was 316mm which was wider than the maximum cavity of 300mm shown by Siderise. Mr Carrick replied the same day,1957 {HAR00004013}. confirming that the information that Mr Lamb had provided was consistent with Siderise's recommendations and that the proposed cavity barrier fell within their standard test data.1958 The void size was less than 325mm and a 25mm air gap was present. He also confirmed that the fixing details shown in Harley's drawings1959 Drawing C1059-305 {HAR00009737}. were acceptable. Mr Lamb did not ask Siderise for any further advice on the cavity barrier strategy.1960 Lamb {Day38/95:10-15}.
¶57.37 Neil Crawford responded to Kevin Lamb's email on 6 March 2015.1961 {SEA00012906}. He confirmed that he had sought advice from Exova, but that his own interpretation was that the fire rating of the cavity barriers would have to follow that of the adjacent walls. He attached the Fire Strategy drawing.1962 {SEA00003101}. Bruce Sounes confirmed that he had not looked at the drawings that Mr Lamb or Mr Crawford had sent him as, by that stage, although he was still nominally leading the design team, Mr Crawford was "fronting it".1963 Sounes {Day21/90:13-25}. When he commented on Harley's revised drawings1964 {SEA00003160}. Mr Crawford did not draw attention to the absence of cavity barriers around the windows as, according to him, the strategy had been simply to have cavity barriers at the junctions between compartments.1965 Crawford {Day11/2:20-25}; {Day11/3:1-5}. Similarly, Mr Crawford did not comment on Harley's note that the cavity barrier was to be cut around the cladding rail because he regarded it as a specialist item and he expected Harley to know what it was doing.1966 Crawford {Day11/6:1-9}.
¶57.38 On 11 March 2015 Kevin Lamb sought further advice from Siderise about the rating of the cavity barriers.1967 Email from Mr Lamb to Mr Carrick dated 11 March 2015 {HAR00003999}. He did not ask where to place the barriers as, in his mind, it was clear where they were going to go and their positioning had been approved in discussions with Harley.1968 Lamb {Day38/118:11-22}. Christopher Mort (Technical Officer for Fire at Siderise) replied on 12 March 20151969 {SIL00000038}. advising that to meet the guidance in Approved Document B the area between the compartment wall and outer cladding needed only to be a cavity barrier (not a firestop) with just 30 minutes' integrity and 15 minutes' insulation. He included in his message a copy of Diagram 33 of Approved Document B,1970 {SIL00000038/7}. which showed cavity barriers around the windows and contained a label reading "Close around openings" with arrows pointing to the top and bottom of the window.1971 {BSD00001779}.
184¶57.39 Mr Mort did not give Mr Lamb any advice about the risks associated with using cavity barriers in a rainscreen system.1972 Mort {Day103/16:19}-{Day103/17:10}. Nor did he provide any information about the limitations of the testing that Siderise had carried out on its cavity barriers.1973 Mort {Day103/17:11-24}. Despite having Diagram 33 expressly drawn to his attention and himself noticing that cavity barriers were marked around the windows, Kevin Lamb took no steps to revise the cavity barrier strategy for Grenfell Tower.1974 Lamb {Day38/120:4-24}.
¶57.40 On 18 March 2015, Ben Bailey sent an email to Neil Crawford telling him that Siderise had given advice about the required rating of the cavity barriers that differed from that received from RBKC building control.1975 {SEA00012953} The email was copied to Daniel Anketell-Jones, Mark Stapley, Robert Maxwell, John Hoban, and Kevin Lamb. Shortly afterwards, Mr Crawford spoke to Mr Hoban, who, on 20 March 2015, sent him an email informing him that the fire rating for any new elements of structure (including the cavity barriers) should be 120 minutes' insulation and integrity and drawing attention to Diagram 33.1976 {RBK00048734}. Mr Hoban was unable to recall the content of his conversation with Mr Crawford.1977 Hoban {Day46/112:10-14}.
¶57.41 On 25 March 2015, Mr Lamb sent revised versions of Harley's drawings1978 Harley drawings 100 {HAR00017787}, 301 {HAR00008901}, 304 {HAR00017785}, 305 {HAR00017784}, 325 {HAR00017783} and 326 {HAR00017782}. to Simon Lawrence with copies to members of the design team.1979 {HAR00017781}. Bruce Sounes, Neil Crawford, Daniel Anketell-Jones, Mark Stapley, Ben Bailey and Robert Maxwell were copied in. The drawings contained revised details of the "firebreaks", the ratings of which had all been increased to 120 minutes' integrity and 60 minutes' insulation.
¶57.42 Following a discussion they had had the day before, on 26 March 2015 Ben Bailey sent an email to Richard Kay, National Facades Manager at Siderise, asking him to identify the regulations which supported Siderise's opinion that cavity barriers with 30 minutes' integrity and 15 minutes' insulation were all that was required.1980 {HAR00004002/3}. He asked Mr Kay to do that because he was not familiar with them himself and was wholly dependent on Siderise for advice.1981 Ben Bailey {Day40/61:21}-{Day40/62:3}. Mr Kay replied the following day, copying in Kevin Lamb and others at Harley.1982 {HAR00004002/2}. He included in his email an extract from Approved Document B1983 Table A1 from Appendix A. which showed that 30 minutes' fire integrity and 15 minutes' insulation were recommended. Mr Bailey was unable to recall the conversation he had had with Mr Kay.1984 Ben Bailey {Day40/61:1-5}.
¶57.43 Ben Bailey forwarded that email to Simon Lawrence and Simon O'Connor on 26 March 2015 with the comment that there was quite a large difference in cost between the cavity barriers that Siderise had recommended (and the project specification required) and the 120 minute cavity barriers suggested by building control.1985 {RYD00037117/2}. According to Neil Crawford, there was pressure from those on site not to specify cavity barriers with 120 minutes' fire resistance due, at least in part, to the additional cost and delay that might be caused.1986 Crawford {Day11/45:1-10}.
185¶57.44 Subsequently Neil Crawford referred the question of the rating of the cavity barriers back to Mr Hoban.1987 {HAR00003947/7}. On 27 March 2015, he sent the email from Siderise to Mr Hoban and asked him to review the position. However, Mr Hoban adhered to his original view and Mr Crawford reported that to the design team later that day.1988 {RYD00037117}.
¶57.45 On 27 March 2015 Ray Bailey sent an email to Simon Lawrence, Neil Crawford and Ben Bailey with copies to Simon O'Connor, Kevin Lamb and Daniel Anketell-Jones, explaining the difference between a firestop and a cavity barrier.1989 {RYD00037117}. Ray Bailey did not comment on the absence of cavity barriers around the windows in the drawings produced by Harley.
¶57.46 Later the same day Ray Bailey sent the exchange to Daniel Anketell-Jones for his comments.1990 {HAR00006585}. Mr Anketell-Jones replied:
"Just that it's ridiculous. There is no point in 'fire stopping', as we all know; the ACM will be gone rather quickly in a fire! The whole point is to stop 'unseen' fire spreading in the cavity and moving to other parts of the building."1991 {HAR00006585}.
¶We have considered that exchange in Chapter 55 where we have set out our conclusions on the choice of ACM PE rainscreen panels for use on Grenfell Tower. Mr Anketell-Jones accepted that in his email he had been expressing an opinion about the risk of fire spreading within the cavity unseen and how that affected the cavity barrier strategy,1992 Anketell-Jones {Day37/22:2-16}. but that did not lead him to think about the importance of preventing fire from spreading from a compartment into the cavity in the first place.1993 Anketell-Jones {Day37/27:9-14}.
¶57.47 On 30 March 2015 Neil Crawford sent another email to Mr Hoban, recommending that he speak to Ben Bailey,1994 {HAR00003947/7}. but he did not check whether Mr Hoban had spoken to Mr Bailey or anyone else at Harley.1995 Crawford {Day11/52:3-7}. Neither Mr Hoban nor Mr Bailey was able to recall whether a conversation had taken place.1996 Hoban {Day46/119:10-17}; Ben Bailey {Day40/70:24}-{Day40/71:15}.
¶57.48 Shortly after,1997 Mr Crawford's email suggesting Mr Ashton contact Mr Bailey was at 12:49. Mr Hoban's response was at 14:22 on the same day. on 30 March 2015, Mr Hoban replied to the project team and Mr Kay of Siderise setting out his view.1998 {EXO00000715/2}. He referred to his email of 20 March 2015 and said that in his view Diagram 33 of Approved Document B required a firestop with 120 minutes' resistance between compartment floors.
186¶57.49 The repeated references to Diagram 33 throughout the email exchanges leaves little room for doubt that all the construction professionals involved either knew or ought to have known that a cavity barrier strategy in accordance with that diagram was required, but regrettably it appears to have been ignored.
The "weak link"
¶57.50 On receipt of Mr Hoban's email of 30 March 2015, Mr Kay asked Harley to send him drawings of the build-up of the cladding so that his technical officer could evaluate the position and provide a formal response.1999 {HAR00003947/4-5}. In response Ben Bailey sent him two drawings2000 Drawing 300 showing a section of the windowsill and Drawing 301 showing a section of the window head {HAR00019402} and {HAR00019403}. with copies to Mr Mort.2001 {HAR00019401}. Mr Kay had also asked for a section drawing through the whole window to give to Mr Mort for comment,2002 As shown on Mr Mort's annotated drawing as "C-C": {RYD00037413}. but Ben Bailey was unable to provide that drawing. That struck Mr Mort as odd, because he would normally have expected to see a full section which clarified the window details.2003 Mort {Day103/29:15}-{Day103/30:13}.
¶57.51 Mr Mort replied the same day.2004 {HAR00018971}. He said:
"I have reviewed the drawings sent over and sketch a proposal to alleviate the issues raised by the BCO, also on the second page of the attachment I have highlighted the weak link so to speak in terms of fire and I think the [building control officer] would have also noticed this. The proposal requires the installation of RH25g 90/60 product in two layers one at the head of the window aligning with the compartment floor and the other at the top of the existing up stand, therefore two layers of 60 minutes protection that overall would provide if tested over 120 minutes protection, at the window locations…"
¶57.52 Mr Mort confirmed that he had prepared two sketches, one to show the proposed solution to increase the fire resistance of the cavity barriers to 120 minutes2005 {HAR00003948}. and one to identify what he called a "weak link" for fire at the head of the window.2006 {HAR00003948/2}. According to him, they were distinct sketches with distinct purposes.2007 Mort {Day103/33:9-19}. The weak link that Mr Mort had identified was a gap at the head of the window, where there was nothing to stop a fire spreading from an internal compartment into the external cavity.2008 Mort {SIL00000298/8} page 8, paragraph 31(c); Mort {Day103/34:25}-{Day103/35:10}. It was a clear error, to which Mr Mort felt he had to draw attention. It was his opinion that Harley or building control ought to have noticed it.2009 Mort {SIL00000298/8} page 8, paragraph 31(c); Mort {Day103/37:24}-{Day103/38:7}.
¶57.53 The first of Mr Mort's sketches described his proposed means of producing cavity barriers with 120 minutes' fire resistance.2010 {HAR00003948}. It showed two pairs of cavity barriers, one pair above the window head and another pair at the sill, each made up of two individual barriers rated 90 minutes' integrity and 60 minutes' insulation to achieve a total of 180 minutes' fire resistance and 120 minutes' insulation.2011 Mort {Day103/38:15-20}. Mr Mort said that it had not been clear from Harley's drawings whether there were vertical cavity barriers at the window jambs. He accepted that the cavity barriers he had added at the sill of the window in his sketch were slightly below the sill itself, but said that the drawing was a schematic rather than a detailed design.2012 Mort {Day103/39:21}-{Day103/40:19}.
187¶57.54 The second sketch which Mr Mort had prepared was based on a drawing produced by Harley, to which he had added a bubble containing the note "weak link for fire".2013 Harley drawing 301 {HAR00003948/2}. The sketch showed the new window set back from the edge of the building, exposing a gap between the window brackets, as shown below.2014 Mort {Day103/36:11}-{Day103/37:3}.
¶Figure 57.1 – Harley drawing 301
¶57.55 Ben Bailey thought that the purpose of Mr Mort's email and sketches was to provide a solution to the dispute about whether there should be cavity barriers or firestopping2015 Ben Bailey {Day40/74:12-17}; {Day40/76:4-11}. and he noticed that Mr Mort had drawn cavity barriers at the head and sill of the window in the first sketch.2016 Ben Bailey {Day40/80:17-24}. However, he did not communicate Mr Mort's views, including about the weak link for fire, to anyone at Studio E, Rydon or building control, despite Mr Mort's having said that he thought that the building control officer would have noticed the problem.2017 Ben Bailey {Day40/75:7-21}; {Day40/86:17-25}. Nor did he ask Mr Mort to clarify exactly what he meant.2018 Ben Bailey {Day40/76:20-25}; {Day40/85:17}-{Day40/86:2}; Crawford {Day11/6:11-15}. Ben Bailey's explanation was that he had read the emails together and, as Mr Hoban had changed his position shortly afterwards, he did not feel the need to refer Mr Mort's email to him.2019 Ben Bailey {Day40/76:12-19}; {Day40/76:4-11}.
188¶57.56 That explanation is far from satisfactory. It made no sense for Ben Bailey to disregard Mr Mort's concerns about the design of the window head simply because the dispute over the rating of the cavity barriers had been resolved shortly afterwards. It was foolhardy to ignore the very clear warning about the design of the window, since it should have been plain to anyone reading Mr Mort's email and reviewing his sketches that the two issues were distinct from one another.2020 {HAR00018971} In particular, Mr Mort wrote in the introductory paragraph: "I have reviewed the drawings sent over and sketch a proposal to alleviate the issues raised by the BCO, also on the second page of the attachment I have highlighted the weak link so to speak in terms of fire."
¶57.57 Later the same day Ben Bailey forwarded the email from Mr Mort to others at Harley, including Ray Bailey and Kevin Lamb.2021 {HAR00003947}. He expected them to read its contents and also the attachments.2022 Ben Bailey {Day40/92:14-20}. Ray Bailey could not recall when he first saw Mr Mort's email and accompanying sketches, but he confirmed that it was before the end of the project.2023 Ray Bailey {Day33/158:5-15}. He did not bring Mr Mort's concerns to the attention of Studio E or building control, nor did he ask Mr Mort to clarify the position.2024 Ray Bailey {Day33/159:17-19}; {Day33/160:2-5}; {Day33/160:8-12}. His explanation was that the email needed to be read in the context of the debate about the requirement for firestopping or a cavity barrier,2025 Ray Bailey {Day33/159:20-23}. but for the reasons set out above, we do not accept that explanation, even allowing for the fact that he may not have seen the email until 1 April 2015, or even later.2026 Ray Bailey {HAR00010184/17-18} pages 17-18, paragraph 69. Whenever he read the email, Ray Bailey ought to have realised that the problem of the weak link was separate and distinct from the question about firestopping. Ray Bailey eventually accepted that the only sensible thing to have done was to raise Mr Mort's concern with building control.2027 Ray Bailey {Day33/160:13-25}.
¶57.58 Mr Lamb denied having noticed Mr Mort's warning about the weak link, despite admitting that he had scanned the email.2028 Lamb {Day38/138:8-20}; {Day38/141:24}-{Day38/142:4}. Mr Lamb did not discuss the drawing with anyone at Harley or anyone else connected with the project2029 Lamb {Day38/142:21}-{Day38/143:2}; {Day38/144:3-5}. and no changes were made to either of the drawings that Mr Mort had annotated.2030 Lamb {Day38/144:6-14}. Mr Mort's email did not prompt Mr Lamb to consider whether the weak link could be rectified by some other change to the design.2031 Lamb {Day38/146:2-15}.
¶57.59 Although Harley had been alerted in that way to the presence of a potential route for fire to spread at the head of the window, it did not take any steps to make good the defect, either by referring it to the design team for discussion, or by revising its design.
The outcome: March–April 2015
¶57.60 On 31 March 2015, Mr Crawford replied to Mr Hoban's email of 30 March 2015.2032 {SEA00000265}. He noted that the subject of fire barriers was causing concern on site, not least due to the effect on programme and cost. He asked for Mr Hoban's earliest response as the matter was beginning to hold up work.
189¶57.61 Mr Crawford sent the correspondence to Mr Ashton and asked for his comment.2033 {SEA00013044}. Mr Ashton responded by email later the same day.2034 {EXO00000715}. He explained that, in his view, a cavity barrier was all that was required, since fire stopping would not stay in place in a fire which would cause the zinc cladding to fail. Mr Ashton was unaware of the type of cavity barrier that had been proposed for use at Grenfell Tower and did not think it necessary to clarify that with the design team at that stage.2035 Ashton {Day18/100:13-21}. Attached to Mr Crawford's email was a drawing produced by Studio E showing a cavity barrier at the head of the window only.2036 Studio E drawing "Proposed Typical Bay Plans, Section & Elevation" {SEA00002499}. However, Mr Ashton did not look at the drawing at the time and therefore did not know where cavity barriers were to be located.2037 Ashton {Day18/123:7}-{Day18/124-10}.
¶57.62 On 1 April 2015 Mr Hoban replied to Mr Crawford saying that he had no objection to the proposal made by the design team, which provided for a cavity barrier with 30 minutes' integrity and 15 minutes' insulation.2038 {HAR00013719/2}.
¶57.63 Mr Crawford replied on the same day2039 {HAR00013719/2}. and sent Mr Hoban two further drawings relating to the lower levels.2040 Detail Sections Sheet 2 Main Entrance 1279 (06) 121 Rev 00 {RYD00037743}; Detail Section Sheet 1 1279 (06) 120 Rev 00 {RYD00037744}. He also attached a drawing made by Harley.2041 Harley Drawing C1059-325 Revision C which was a Walkway +1 Level Section {RYD00037745}. Mr Hoban replied to that email, thanking Mr Crawford for the further drawings and confirming that he had no adverse comments.2042 {HAR00013719}. Simon Lawrence sent that email onto Ben Bailey and Ray Bailey,2043 {HAR00013719}. copying Neil Crawford and Simon O'Connor shortly afterwards and informing them that the building control officer now agreed that the fire protection in the cladding should be a cavity barrier rather a fire stop. Ray Bailey was aware that the drawings did not show cavity barriers around the windows but did not check with Rydon or Studio E whether building control had made any comments on that omission.2044 Ray Bailey {Day33/155:20}-{Day33/156:3}. Mr Crawford did not expressly seek guidance from building control about the location of cavity barriers around the windows2045 Crawford {Day11/61:24}-{Day11/62:4}. and we have seen no evidence that he asked Mr Hoban to approve or comment on Harley's cavity barrier strategy as a whole.2046 Crawford {Day11/62:10-13}. For his part, Mr Lawrence was unaware that there ought to have been cavity barriers around the windows.2047 Lawrence {Day25/13:18-22}.
¶57.64 When Mr Lawrence was asked what steps he had taken to ensure that cavity barriers were included as required in the external wall design, he said that he had used a lead designer and a specialist subcontractor and had consulted building control.2048 Lawrence {Day24/184:8-13}. He accepted he had been largely a spectator in relation to the exchange of correspondence in March 2015 emails, as did the project manager, Mr O'Connor.2049 Lawrence {Day25/8:1-4}; O'Connor {Day26/153:11-13}. Mr Lawrence's evidence, however, betrayed a failure to understand his responsibility for ensuring that the external wall of the building complied with the requirements of the Building Regulations. There were many occasions in the course of that correspondence when it was, or should have been, clear to Mr Lawrence that Harley needed assistance2050 Email from Kevin Lamb to Simon Lawrence dated 3 March 2015 {HAR00017738}. which it was not receiving from Studio E.2051 Email from Neil Crawford to Kevin Lamb, copying Simon Lawrence and others dated 3 March 2015 {EXO00001461}. Mr Lawrence was surprised that Studio E required advice on a query of this nature, Lawrence {Day24/191:20-24}; but this did not trigger him to consider Studio E's competence, {Day24/193:2-11}. It was also clear that there was a significant degree of confusion over whether and to what extent cavity barriers were required2052 Lawrence {Day24/193:2-11}. and that consideration should have been given to obtaining specialist advice. Mr Lawrence was not alive to any of these problems.2053 Lawrence {Day24/185:13-18}. He should have been.
190Further advice from Siderise
¶57.65 Harley contacted Siderise on a number of other occasions during the life of the project seeking advice about cavity barriers.2054 Emails 6 May 2015 {HAR00004238}; 17 June 2015 {HAR00019012/2}. Despite that, it did not occur to Ben Bailey to inform himself about the guidance which was available in Approved Document B.2055 Ben Bailey {Day40/110:24}-{Day40/111:9}. The correspondence demonstrates a concerning lack of knowledge and expertise within Harley in relation to the use and siting of cavity barriers, which led to undue reliance on the advice of the manufacturer. Ben Bailey was unable to explain that lack of expertise and could not recall whether he had sought advice from Mr Anketell-Jones, Mr Lamb or Studio E.2056 Ben Bailey {Day40/113:3}-{Day40/114:3}. It was reasonable to expect Harley, as a specialist cladding contractor, to possess a degree of technical knowledge about the function of cavity barriers in ensuring compliance with the Building Regulations, but the evidence shows that it did not. The piecemeal requests to Siderise demonstrate the pitfalls in failing to articulate a clear and detailed cavity barrier strategy at the design stage before construction work began.
Installation of the cavity barriers
¶57.66 The installation of the external facade, including cavity barriers, was carried out by Osborne Berry Ltd as a subcontractor.2057 Ben Bailey {HAR00010060/3} page 3, paragraph 11. Mr Osborne had no formal training in the installation of rainscreen cladding facades.2058 Osborne {Day43/72:9-12}. The company had no experience of installing cavity barriers with intumescent strips and, as far as Mr Berry was aware, it had not previously installed cavity barriers manufactured by Siderise.2059 Berry {Day44/41:4-22}. Harley did not maintain a permanent presence on site and there was no clerk of works in the traditional sense, so there were times when Osborne Berry and their workmen were unsupervised when installing the facade.2060 Ben Bailey {Day40/120:17}-{Day40/121-3}.
¶57.67 A subcontractor progress meeting was held on 28 April 2015. The minutes record that Ben Bailey was to issue elevation drawings to Daniel Osgood, a Rydon site manager, showing the position of the cavity barriers.2061 {HAR00000414}. The minutes also recorded that windows and "firebreaks" were being fitted to the north, east and west elevations.2062 {HAR00000414/3}. It therefore appears that the work of installing cavity barriers had begun before Harley had issued a full set of drawings. Mr Osgood said that he had assumed that Osborne Berry knew from experience where to place the cavity barriers.2063 Osgood {Day30/146:25}-{Day30/147:4}.
191¶57.68 Ben Bailey did not recall having given Osborne Berry any guidance on how to install the cavity barriers.2064 Ben Bailey {Day40/134:4-18} such as the Siderise document "RH and RV cavity barriers for use in the external envelope or fabric of buildings" {HAR00008668}. Mr Osborne had never seen any such guidance, nor did he ask for any while he was on site.2065 Mr Osborne confirmed he had not seen either Siderise document shown to him {SIL00000230} or {SIL00000227}. Osborne {Day43/139:5-21}. He accepted that he should have checked that he understood how to install the product, which he had not fitted before, but apparently it did not occur to him at the time to do so.2066 Osborne {Day43/140:7-11}. Mr Berry had not seen any Siderise literature containing guidance on the installation of cavity barriers during the time he was working on the Grenfell Tower project, nor had he looked for guidance on Siderise's website.2067 Mr Berry was shown the guide at {SIL00000227} and confirmed that he did not read any guide like it while he worked on the project; Berry {Day44/45:12-14}; {Day44/49:18-22}. At the time that Osborne Berry was training their fitters, only horizontal cavity barriers were available on site.2068 Berry {Day44/46:4-9}.
¶57.69 Mr Osborne confirmed that the cavity barriers above the windows had been fitted above the level shown on Harley's drawings2069 Osborne {Day43/98:6-21}. to prevent the fixing brackets penetrating the EPDM membrane.2070 Osborne {Day43/97:5-18}. He said that the change had been specifically agreed on site after Osborne Berry had produced a mock-up of a sample cladding arrangement.2071 Mr Osborne's evidence was that this was agreed by either Daniel Anketell-Jones or Kevin Lamb at an early stage in the construction process, Osborne {Day43/97:25}-{Day43/98:5}; {Day43/98:22-24}. He also said that it had been impossible to install the vertical cavity barriers under compression, as recommended in the Siderise product literature,2072 {SIL00000227/6}: "This cavity barrier is fitted vertically under compression, completely filling the void." because the method of attaching the cassettes to the supporting rails allowed the cavity barrier to push the panel away from the building.2073 Osborne {Day43/142:13-21}. Mr Osborne did not raise the problem with anyone on site nor did he investigate a solution with Harley.2074 Osborne {Day43/142:23}-{Day43/143:7}. Osborne Berry instructed their fitters to trim the cavity barriers on site as the gap between the original concrete and the facade differed at different levels on the building.2075 Berry {Day44/51:13-21}.
¶57.70 Mr O'Connor did not attempt to check the positions of the horizontal cavity barriers against the drawings, because that was not his personal responsibility, and he therefore did not notice that they had not been positioned in accordance with the drawings.2076 O'Connor {Day26/166:25}-{Day26/167:6}. However, he accepted that placing them incorrectly constituted defective workmanship, for which Rydon (amongst others) would be responsible.2077 O'Connor {Day26/167:24}-{Day26/168:15}. He would have expected that kind of poor workmanship to be picked up under Rydon's quality assurance and inspection regime and could not explain why that had not happened.2078 O'Connor {Day26/172:18-25}.
¶57.71 Ben Bailey was responsible for supervising Osborne Berry's work on site on behalf of Harley2079 Ben Bailey {HAR00010060/3} page 3, paragraphs 11-13. but he had not received any training that would enable him to ensure that the installation of the cavity barriers complied with the manufacturer's advice, directions or guidance.2080 Ben Bailey {Day40/138:15-19}. He thought it was likely that he had reviewed Siderise's product literature and installation guidance,2081 Ben Bailey {Day40/153:24}-{Day40/154:2}. but according to Mr Berry he gave Osborne Berry no specific guidance about how the cavity barriers were to be fitted.2082 Berry {Day44/55:12-16}. Ben Bailey conducted visual inspections of the windows, insulation, cavity barriers and cladding rails before the cladding panels were installed on the north, east and west elevations, but not on the south elevation.2083 Ben Bailey {HAR00010060/4} page 4, paragraph13; Ben Bailey {Day40/148:13-19}; {Day40/149:17-20}. No formal record was kept of those inspections.2084 Ben Bailey {Day40/146:15-20}. Ben Bailey's inspections involved ensuring that the components had been installed in the same way as on the previous bays; he did not check the work against the drawings.2085 Ben Bailey {Day40/150:4-17}. He did not notice any poor workmanship or flaws in the installation during any of his inspections.2086 Ben Bailey {Day40/150:19-23}.
192¶57.72 After the fire the remaining cavity barriers were inspected and found to have various defects. In particular, a. The horizontal cavity barriers were found to have been installed with air gaps in
excess of 25mm and in some places the material had been poorly cut and fitted to the surrounding structure with gaps between adjacent barriers at joints.
¶b. Gaps had been left between the vertical cavity barriers and the cladding panels. c. Incorrect fixing brackets had been used. d. In some cases the fixing brackets had been spaced too widely. e. Some cavity barriers in the area of the columns were missing or had gaps.
¶f. Horizontal cavity barriers had been used in the vertical position, with the intumescent edge installed directly against the concrete.2087 Dr Lane, Phase 1 Report {BLAS0000008/40-48}; Swales {SIL00000306/25-26} pages 25-26, paragraphs 97-101.
¶57.73 Ben Bailey said he had been very shocked when he was shown photographs of the cavity barriers taken after the fire. He said that he had not seen workmanship like that when he had been on site or when he had conducted his checks.2088 Ben Bailey {HAR00010060/10} page 10, paragraph 32. In his witness statement he sought to explain why he had not noticed the problems with the installation of the cavity barriers by saying that the insulation boards had obscured the junction between the concrete walls and the back of the cavity barriers, making it impossible to see any defects without dismantling and causing damage to the completed works.2089 Ben Bailey {HAR00010060/10} page 10, paragraph 32. However, that is in contrast with Mr Berry's evidence that there had been plenty of opportunities to inspect the cavity barriers before the insulation was fitted.2090 Berry {Day44/59:9-14}. Ben Bailey conceded that he ought to have been conducting inspections at each stage of the installation.2091 Ben Bailey {Day40/164:1-9}. If he had done so, he would have inspected the work before the insulation obscured the rear of the cavity barriers and at a time when the problems would probably have come to light. As it was, Harley's inspections of Osborne Berry's work were insufficient to ensure that the defects we have described were identified.
193¶57.74 Mr Hoban of RBKC building control also visited the site and carried out inspections. He had not received any training on the installation of cavity barriers in cladding systems,2092 Hoban {RBK00050416/11} page 11, paragraph 34g; Hoban {Day46/126:20}-{Day46/127:4}. or indeed cladding systems more generally,2093 Hoban {Day46/126:20}-{Day46/127:4}. but a building control officer could be expected to be shown on site what to look for and to be aware of the need to check the manufacturer's instructions about how the barriers should be installed.2094 Menzies {Day60/109:24}-{Day60/111:4}. Mr Hoban did not check whether cavity barriers had been installed around the windows because most of the windows had by that time been installed and therefore it was not possible to see where the cavity barriers should have been.2095 Hoban {Day46/98:4-11}. He did not ask to look behind the windows because he had seen cavity barriers being installed in other locations and so did not think it necessary to do so.2096 Hoban {Day46/98:14}-{Day46/99:5}. Mr Hoban accepted that he should have checked whether cavity barriers had been fitted around the windows but that he had failed to do so.2097 Hoban {Day46/99:20-25}.
¶57.75 Mr Hoban's evidence was that he would know through reading cavity barrier documentation how cavity barriers were to be installed.2098 Hoban {Day46/127:13}-{Day36/128:1}. However he also accepted that the lack of training meant he had been unable to detect whether the cavity barriers within the facade had been properly cut and installed or whether the right kinds of cavity barriers had been placed in the right positions.2099 Hoban {Day46/127:6-12}. He thought that the cavity barriers that he had been able to inspect when he went up the mast climbers were acceptable, and although he saw them being installed, the workmen were covering them up as they went along.2100 Hoban {Day46/128:10-20}. At no stage did he ask for a cassette to be removed so that he could check the installation of the cavity barriers.2101 Hoban {Day46/189:21}-{Day46/190:6}; {Day46/191:24}-{Day46/192:13}. Mr Hoban was unable to recall whether he had seen cavity barriers in place before they were covered by insulation.2102 Hoban {Day46/130:11-20}. He did not notice that the horizontal cavity barrier at the head of the window was being installed at a level higher than that shown on the drawings made by Studio E.2103 Hoban {Day46/130:21-25}.
¶57.76 Mr Jonathan White of John Rowan Partners, which was engaged by the TMO to provide site supervision and inspection services, told us that it was not part of his job to check for compliance with the Building Regulations.2104 White {Day42/112:11}-{Day42/113:4}. His role, as he saw it, was to find out whether building control had expressed any concerns about the work and report back to the TMO.2105 White {Day42/165:7-13}. Mr White did not see design drawings of the windows2106 White {Day42/158:2-12}. and did not notice during his inspections that there were no cavity barriers around the windows.2107 White {Day42/165:1-3}. Although he inspected the cavity barriers and insulation, he was generally concerned only with whether the installation was consistent and the work neat and tidy.2108 White {Day42/171:4}-{Day42/172:9}. He told us that he would have picked up any obviously poor workmanship, such as poorly fitted cavity barriers, but not defects such as horizontal barriers in a vertical orientation.2109 White {Day42/176:20}-{Day42/179:24}.
194Siderise inspection at Wayland House
¶57.77 In December 2014, before Harley had begun installing the cladding at Grenfell Tower, Mr Kay of Siderise inspected the work on another of its projects, Wayland House in Brixton,2110 {SIL00000321}. which involved a curtain wall refurbishment. Mr Kay inspected the firestopping following the installation of Siderise's Lamatherm system. Following his inspection, on 19 December 2014 Mr Kay reported to Harley on the quality of the work. He found a. Installation of fire barriers in the incorrect orientation. b. Areas where the fire barriers had not been installed under sufficient compression, leaving gaps or loose material in the cavity. c. Gaps between the vertical fire barriers and the structure. Mr Kay considered it shocking to see so many defects in a cladding system2111 Kay {Day103/97:17-25}. and asked Harley to arrange for him to visit the building again when remedial works had been carried out.2112 {SIL00000321/3}.
¶57.78 Mr Kay confirmed that a similar inspection service would have been provided to Harley in relation to the Grenfell Tower project,2113 Kay {Day103/106:20}-{Day103/107:23}. but that no one from Harley had asked Siderise for it.2114 Kay {Day103/175:15-17}. Ben Bailey was unaware of the email or Mr Kay's findings when he began his work on the cavity barriers at Grenfell Tower.2115 Ben Bailey {Day40/157:23-25}. Nor did he know whether anyone at Harley had communicated those findings to Osborne Berry so that lessons could be learned.2116 Ben Bailey {Day40/158:5-10}. Harley failed to learn from the experience at Wayland House and did not make use of Mr Kay's report to ensure that standards were improved at Grenfell Tower.
Cavity barriers in the crown
¶57.79 Neither the second2117 Dated 29 November 2013 {SEA00000153}. nor the third2118 Dated 30 January 2014 {SEA00000169}. version of the NBS Specification contained any detailed information about the crown; each of them simply indicated that that part of the work was still to be completed.2119 At Clause 130 in Section H92 where it stated: "Major Nonstandard Components 'Crown': Manufacturer: TBC - Product Reference: TBC. Material: TBC. Finish: TBC…" {SEA00000153/66} and {SEA00000169/67}. Mr Sounes accepted that because the details of the crown had not yet been confirmed, little consideration had been given to where cavity barriers were to be placed within it.2120 Sounes {Day 21/92:16-22}. During Mr Rek's time working on the Grenfell Tower project (September to December 2013) no detailed design work had been carried out on the crown and questions relating to the design, material, finish and fixing were left until after the NBS Specification had been sent out to tenderers.2121 Rek {Day12/86:12-17}; {Day12/87:12-16}.
¶57.80 As part of the Employer's Requirements prepared for the tender, Studio E prepared a drawing which showed a cross-section of different floors of the tower, including the top floor and roof (or "plant") level.2122 Drawing entitled "Detail Section Sheet 1" {SEA00002551} dated 26 September 2013 with reference 1279 (06) 120 Rev 00. The drawing bore a label "Design of the crown detail TBC by architect". One cavity barrier was shown at the head of the window between the top floor and the roof level. There were, however, no other indications of where cavity barriers would be located within the crown. Mr Sounes accepted that little thought had gone into the matter at that stage.2123 Sounes {Day21/92:19-22}. Studio E never produced any elevation drawings showing how the horizontal cavity barriers at the top of the building would meet the vertical cavity barriers.2124 Sounes {Day21/93:8-16}. Mr Sounes confirmed that the risk that the crown might contribute to the spread of a fire in the external wall had not been considered because no one had been aware of the risks posed by ACM panels.2125 Sounes {Day21/101:5-20}.
195¶57.81 Mr Crawford was involved in the design of the crown after Studio E had been novated to Rydon.2126 Crawford {Day11/63:1-3}. He did not consider whether cavity barriers were required over and above those that would be fitted around compartments.2127 Crawford {Day11/63:7-12}. Since there were no compartments in the crown itself, it was his view that there was no requirement for cavity barriers.2128 Crawford {Day11/63:22}-{Day11/64:8}.
¶57.82 On 29 May 2015 Mr Lamb sent Mr Crawford an email attaching drawings of the crown and asking for his approval.2129 {SEA00013221}. On 12 June 2015, Mr Crawford replied attaching his comments on the design.2130 {SEA00013221}. His annotated drawings2131 {SEA00003242}. showed vertical cavity barriers which terminated at the base of the crown but no horizontal cavity barriers at the head of the columns.2132 Crawford {Day11/66:9-11}. Harley's drawings2133 For example C1058-216 {SEA00003242}. did not show a horizontal cavity barrier at the head of the columns or at the base of the crown, unlike the drawing produced by Studio E.2134 Entitled "Detail Section Sheet 1" {SEA00002551} dated 26 September 2013 with reference 1279 (06) 120 Rev 00. Mr Crawford agreed that that represented a worsening of the design2135 Crawford {Day11/69:20-25}. but he did not mention that when he commented on the drawings.2136 Crawford {Day11/70:3-9}. There was no discussion between Harley and Studio E about the provision of a cavity barrier at the head of the columns.2137 Crawford {Day11/71:24}-{Day11/72:4}.
¶57.83 Mr Lamb intended to revisit the question of a cavity barrier in that location and left himself a note on the CAD2138 Computer Aided Design. version of the drawing to remind him to do so.2139 {HAR00010427}; Lamb {Day38/166:17}-{Day38/167:2}. However, the note appeared only on Mr Lamb's CAD file; it did not appear on the printed versions of the drawing and therefore no one else saw it.2140 Lamb {HAR00010419/10} page 10, paragraph 36. Mr Lamb said that there had been a discussion within Harley and that it had been felt that there was no need to include a cavity barrier at the head of the columns,2141 Lamb {Day38/163:23}-{Day38/164:5}. but he was unable to recall who in Harley had been involved in that discussion.2142 Lamb {Day38/164:12-13}. At any rate, the drawing was issued for the architect's comments without a cavity barrier.2143 Lamb {Day38/162:10-17}. Mr Lamb explained that the drawing had then been overlooked and that it had never been re-issued as a drawing for construction.2144 Lamb {Day38/165:7-14}. However, that did not cause him any concern because Mr Crawford had not commented on the absence of a cavity barrier in that location. In his view, therefore, there was no need to revisit the point.2145 Lamb {Day38/165:20-24}; see Mr Crawford's annotations on the drawing at {RYD00043547/4}. Despite Mr Lamb's evidence we think it unlikely that he did discuss the matter with anyone else at Harley and that he simply overlooked it.
196¶57.84 For his part, Daniel Anketell-Jones did not give any thought to whether steps needed to be taken to reduce the risk of fire spreading at the top of the building or around the crown.2146 Anketell-Jones {Day37/52:16-23}. and no discussions took place among the construction professionals about the risk of vertical or horizontal spread of fire at the level of the crown.2147 Anketell-Jones {Day37/52:25}-{Day37/53:14}. Work on the crown was left quite late because Harley was concentrating on the large area of cladding represented by the elevations of the building.2148 Lamb {HAR00010419/9} page 9, paragraph 35. As a result, Mr Lamb based his design for the crown on very brief drawings from the architect and a design team meeting on site.2149 Lamb {Day38/162:1-2}.
¶57.85 Mr Hoban's understanding was that cavity barriers were not required at the junction between the cladding and the crown because the crown did not represent a concealed space.2150 Hoban {Day46/102:10-19}. Accordingly, despite the fact that he inspected the crown,2151 Hoban {Day46/138:1-3}. he did not remark on the absence of cavity barriers or any other fire mitigation measures in that location.
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