Taylor Woodrow Anglian Large Panel Systems - A History by Sam Webb
Sam Webb (RIBA) undertook significant research into the construction of the Ronan Point tower block and other "Large Panel System" buildings following the collapse of the flats after a gas explosion in 1968.
This piece is an open letter by Webb relating to Lannoy and Hartopp points, two TWA blocks on the Aintree Estate in Hammersmith and Fulham. The very same issues apply at the Ledbury Estate, which is also part of the ‘Morris Walk series’.
INTRODUCTION I first became aware of the problems of the breakdown of the fire compartmentation in these two tower blocks as long ago as November 1983. That is 34 years ago. From speaking to the tenants in 1983 these faults had been there since they were built c1967. I found the same faults at floor and ceiling levels in Ronan Point and the other similar 8 blocks on that estate. The problem of differential bowing of “sandwich” concrete panels has been known about since the 1950s when the Building Research Station - now the BRE - wrote a report on it. Many schoolchildren will have carried out an experiment in Physics where they heated a bimetal strip of copper and steel. As one metal expands faster than the other the strip bends. This is what happens to the non-loadbearing panels on sunny days. These two blocks were designed and built using the same structural system used for Ronan Point. While they are different in planning and appearance to Ronan Point, structurally, they are much weaker, a point I will come to later. The first Taylor Woodrow Anglian blocks built in the UK were built for the LCC at Morris Walk in Greenwich. They formed part of a serial contract of 1850 flats built in the LCC Inner London area. The erection teams were trained at Morris Walk. The faults subsequently found in Ronan Point will be found in all the blocks in the Morris Walk Series as many of these men worked on all these estates. Indeed the quality of workmanship I found in Ronan Point was found all over the country.
The Great British Housing Disaster This film by Adam Curtis was the only way, at that time, I could uncover what had really gone on in the building industry. It was based on two of my lectures I gave my post graduate students at Canterbury School of Architecture. Towards the end of the film there is a meeting that the tenants of Lannoy & Hartopp arranged with the Council. I arranged for it to be filmed. In July 1968, George Fairweather FRIBA gave the joint evidence we had both prepared to the Ronan Point Inquiry. He was the Chairman of BSCP3 Chapter IV (1962) and later BSCP3 Chapter IV (1972). Both applied to blocks of flats and maisonettes. Some days before he gave evidence it was decided that the Tribunal would not hear any evidence about fire and would just concern itself with gas explosions and progressive collapse. He was not cross examined and the Treasury Solicitor, who had asked for 55 copies of his statement of evidence, lost every copy.
In March 1970 I read the entire set files of nearly 40 files from the Ronan Point Inquiry in the Ministry of Housing & Local Government. This took me 3 1/2 weeks. It is mentioned in Hansard:
Hansard In 1984 Mrs Thatcher agreed to the release of all the files I had read in 1970. In early 1985 I went to the Department of the Environment with Nigel Spearing MP (Newham South). We found half the files I read in 1970 were missing. The files are now in the Public Records Office in Kew. FIRE RISK AND POSSIBLE PROGRESSIVE COLLAPSE:
RONAN POINT FIRE TEST 1968 Some of these defects, gaps opening up at floor and ceiling levels and at the ends of “party walls” or compartment walls between flats, are extremely serious defects. A fire in one flat could spread sideways and vertically, certainly upwards, and possibly downwards as well. The structural movement, caused by the expansion of floor and wall panels, could trigger progressive collapse. A fire could prove especially dangerous if it broke out at night and people were overcome by fumes in their sleep and became unable to raise the alarm, so there was delay in dealing with the fire. This could lead to part of the building collapsing. In July 1984, a full scale fire test in a third floor flat in Ronan Point caused so much structural movement at critical joints such as the H2, that it had to be stopped after 10 minutes. This fire test was ordered, on my advice, by Cllr Fred Jones the Chair of the Housing Committee. It was conducted under the control of the BRE, the Fire Research Station (FRS) and the London Borough of Newham’s Engineer’s Department. I insisted that West Ham FB were present at all times. It was in a flat, in what was claimed to be, a 1 hour building. The most critical joint in this system is the joint where the unreinforced nibs at the end of the floor slab rest on a narrow ledge formed at the top of the external load bearing flank wall panel. This joint is known as the H2 joint. During the fire the 3rd floor H2 joint moved so much out of plum, that the Newham engineers in charge of the test ordered the fire to be extinguished. The engineer in charge was later interviewed on BBC Newsnight in early August 1984 where he stated that he did not wish to be responsible for the second collapse of Ronan Point. Certainly when I met him, as he emerged from Ronan Point, he gave me the impression that he thought Ronan Point would collapse. He said so to me, and issued instructions to clear the area.
A recognition of this particular weakness of this form of construction is is to be found in para 216 of the Ronan Point Report which is attached. Following this the BRS did write a letter of complaint about me, to my then employers, the Board of Governors of Canterbury College of Art, the Principal of the College and the Head of the School of Architecture. I am not sure what they expected to achieve because the Board of Governors had granted me a Sabbatical in order to carry out this work. In 1983 the Chairman of the Housing Committee, Cllr Fred Jones, who became Leader of the Council in 1984, had asked me to advise him about defects in Ronan Point and 8 similar blocks on the Freemason’s Road Estate in Canning Town. These blocks consisted of 22 storeys of Large Panel System built flats, on a two storey insitu-concrete podium. Each floor had five flats and there were 110 flats per block, so there were 990 flats on the estate. All were subsequently dismantled and every joint recorded. Not one single structural joint on the entire estate was found to comply with the drawings prepared by the contractor’s own consulting engineers, Phillips Consultants. This included supposedly improved joints redesigned after the collapse. It was possible to verify this by the dates on newspapers which had been stuffed in structural joints. These proved that the same slipshod method of construction continued after the partial collapse of Ronan Point and a Public Inquiry which claimed the “standards of both workmanship and supervision have been painstakingly investigated. It is no exaggeration to say that the building has been put under the microscope”. Para 111 Ronan Point Report. This statement was patently untrue. It is a good example of what I used to describe to my students as, “solemn nonsense”. As soon as the first load bearing wall panels were removed from the top floor of Ronan Point it was found that up to 50% of the dry pack mortar, which should have been holding up the walls was missing. The joints were also full of floor sweepings, bottle tops, cigarette ends etc. This was widely reported in the press at the time. The entire weight of the flank wall of 22 storeys of flats was being carried at the bottom of one side of the building on the nuts on 12 lifting bolts. These lifting bolts were never intended to carry any load. The nuts were there to raise or lower the wall panel so that a level datum could be achieved to position the next floor. After the dry pack was rammed under the wall and had set, the nuts were supposed to be lowered. Had that been done, then Ronan Point would have collapsed during construction. These faults were found in every one of the 9 blocks dismantled starting with Ronan Point. The erection teams who built Morris Walk in Greenwich, were, as I have mentioned earlier, the same men who built all of these estates.
During the demolition of Ronan Point in 1972 a series of newspapers was given to me by the demolition team. They had been found stuffed in a H4 cross wall joint in flat 77 on the 16th floor. The significant factor, of this find, was the date of a copy of the Daily Mirror. It was 9 September 1972. This meant that the newspaper was put there in the SE corner when Ronan Point was rebuilt after the collapse and public inquiry. This was reported in piece written by a young reporter called Hugh Muir and published in the Newham Recorder 9 October 1986. Hugh Muir covered progress on a very regular basis. The story was also covered in the Technical Press, most notably Building Design (BD) by Alan Thompson and the editor Paul Finch. Having seen the evidence, Alan Thompson contacted Phillips Consultants Ltd for their comment. They had prepared all the drawings and supervised the construction in 1967. He put to them the following points: - Hand-packed mortar in the H2 joint is up to 50% less than specified by the building’s designers.
- The in-situ concrete is poorly compacted, with voids underneath the horizontal reinforcement bars.
- Levelling nuts had not been wound down after the hand packing had been carried out and a significant part of the load was being transferred via the bolts.
These points were put to the engineer Barry Russoff of Phillips Consultants Ltd who supervised the original construction. He told BD that, “ ‘the flank wall joints do not need to be fully packed’ and only 50% of the mortar specified could be sufficient.” - BD 10 October 1986 page 6. Even the hardened Newham engineers who had been in post when Ronan Point was built, and had resisted demolition from day one, were shocked by those comments. The significance of what was found in flat 77 on the 16th floor of Ronan Point is an indication of the poor standards of workmanship not just in Ronan Point and the 8 other blocks on the Freemasons Road in Canning Town, but is indicative of the work throughout the TWA Morris Walk Series. TWA had a pool of men to call upon to erect these buildings. As the same gangs of men were moved from site to site around London, they would have left examples of the same shoddy workmanship. It was their stock in trade, even after Ronan Point had fallen down. Put simply it was in the DNA of Ronan Point. INVESTIGATIONS AT HARTOPP & LANNOY POINTS WITH DAVID ADLER, CHIEF STRUCTURAL ENGINEER LBH&F 1983-1984 I was first invited to visit Lannoy and Hartopp Points in November 1983, by David Adler, then the Chief Structural Engineer for the London Borough of Hammersmith and Fulham. In 1983, Mrs Thatcher had announced that her government was going to abolish the Greater London Council. Although these buildings were built in Hammersmith and Fulham, they were designed and built by the LCC/GLC as part of a serial contract with Taylor Woodrow Anglian to produce some 1800 flats for the LCC. This contract and the flat’s design was known as the Morris Walk Series after the first estate built in Greenwich by the London County Council or LCC. Before these two blocks, Lannoy and Hartopp Points were handed over, David Adler was asked to carry out a structural assessment and conditions survey of them. At that time, they were less than 20 years old and Hammersmith and Fulham would become liable for the considerable burden of that loan repayment for the next 40 years at least, or possibly more. They would also have to pay for maintenance. So it was very important that David Adler gave an accurate forecast as to the condition of the buildings in 1983 and their future behaviour. In doing that he was safeguarding not only the tenants living there at the time but future tenants, the council and all the future residents of Hammersmith & Fulham who would have to pay off the loan and continue to pay for it now. When I first met David Adler he was carrying out investigations in at least two void flats. David Adler had been investigating voids in the H2 joints by means of a single lens reflex camera fitted with a flexible attachment which he was able to feed a considerable distance into the H2 joint. This indicated there were continuous voids where there should have been concrete or drypack mortar. I had found similar defects in an estate called Hunslet Grange in Leeds. This was built in a LPS called Yorkshire Development Group or YDG. It has been demolished.
RONAN POINT INQUIRY INVESTIGATIONS BY BERNARD CLARK & PTNRS ENGINEERS FOR
THE NORTH THAMES GAS BOARD AND THE IMPERIAL COLLEGE TEST ORDERED BY TWA IN 1968 During inquiries made after the partial collapse of Ronan Point following a minor gas explosion, it was discovered just how weak the structure of these buildings were, and still are, especially if a lateral force is applied. Two days after the collapse, Cleeve Barr the Chief Architect of the National Building Agency, and Dr Chan its Chief Structural Engineer, visited Ronan Point. They reported back directly to James Callaghan MP, the Home Secretary, who sent them. Their report stated: “..............The gable loadbearing wall being the most likely to have failed at an initial pressure in the order of 200 lb per square foot or 1.4 lb per square inch.” The Minister then ordered work to cease on every LPS scheme in the UK. Taylor Woodrow immediately had a test rig set up at Imperial College which was conducted for them by Dr Chapman. This test was observed by Bernard Clark a Consulting Engineer and Expert Witness for the North Thames Gas Board. These are his observations from his preliminary report of 27th May 1968: "The test comprised of setting up two vertical heights of wall each approx. 2’6” high (0.762m) above and bellow a piece of floor slab extending outwards from the wall by 4’0” (1.200mm) approx. A vertical load was applied by jacks….Horizontal jacks were positioned equidistant above and below the slab……." Clark concluded: “The value of this test is nil for the following reasons:- 1. The wall heights used gave a height over thickness value 3 times as strong as on the actual wall… 4. ….The test set up contributed nothing valuable as it did not simulate the actual dimensions and conditions on site. To assimilate actual conditions a wall thickness of 2” (50mm) should have been used if only 2’6” (0.762mm) is used, since if some dimensions are scaled down then logically all must be scaled down.” This was signed L.G.Clark. He was Bernard Clark’s brother. Nevertheless these test results were accepted by HMG and when they were announced to the public inquiry the ban on LPS was immediately lifted. The result of that was between May 16 1968 - the partial collapse of Ronan Point - and 8 November 1968 - the publication of the official report, the number of LPS blocks doubled. The government found itself in a delicate situation. It had gone along with and accepted the findings of the Imperial College test. That test was now revealed to be worthless and the government now found itself faced with twice as large of a problem as it had on 16 May when the SE corner of Ronan Point collapsed in the first place. If it had ordered the demolition of these buildings it would have found itself embroiled in many claims.
THE GLC, MINISTRY OF PUBLIC BUILDINGS & WORKS, THE BRE AND CIRCULARS 62/69 & 72/68
Eric Bunn was the Chief Engineer at the GLC. He took up his post on 1 May 1968 two weeks before the collapse. He produced a statement, then had second thoughts. He then had a further meeting on 3 July 1968 with a Mr Humphries of the Treasury Solicitors Department. In his note Humphries said: “Bunn said his enquiries which he would have to make before writing another statement may well cause alarm since the Larsen Nielsen System introduced by Taylor Woodrow Anglian had undoubtedly been modified as the years went by and it could be said that the earlier buildings were not as stable as the present ones.” Bunn never produced his second statement. He was going on holiday from 12 July until 1 August. He gave evidence on the previous “safe” report, ie it was safe in that it was non-contentious and then went on holiday. None of this was ever given in evidence. The Treasury Solicitor then asked the two most senior engineers directly employed by the Government for their opinion. This is the Report of L.R.Creasy Chief Engineer of the Ministry of Public Buildings and Works dated 15 July 1968: “Following the more detailed studies which have since been made - I would not now “feel safe” in living in the end and corner rooms of a T.W. building even if gas were prohibited.” On 17 July 1968 Dr Thomas the Head of the Building Research Station reported: “Even if gas were forbidden I should feel less safe living in a building of the Ronan Point type of construction than I would in a building of most other forms of construction.”
Neither of these two senior Government experts were ever called to give evidence. If they felt unsafe, with their superiour knowledge, why were the tenants just moved back in? In mid August 1968, the full sized test rig of the H2 joint set up at the BRS failed at 1.8psi. This coincided with the calculations made by the NBA two days after the collapse. At this point the Minister of Housing and Local Government the Rt Hon Anthony Greenwood MP ordered all piped gas supplies to be shut off in every LPS block of flats in the UK.
The report of the public inquiry was published in November 1968. The LPS industry suddenly demanded a standard to build to. The government issued Circular 62/68. This said every block should be able to withstand an explosive force of 5psi (34kN/m2). Every block was tested to that standard and every block failed. The government was very unwilling to pay large damages. So it issued a new Circular 72/68. This said if piped gas was removed the explosive force could be reduced to 2.5psi (17kN/m2). On 1 April 1970 the Government announced the introduction of the 5th Amendment to the Building Regulations. This is also known a disproportionate collapse. Originally it applied to all buildings above 5 storeys (including a basement). Since 2004 it has applied to all buildings. Grenfell Tower would have been constructed in line with the 5th Amendment 1970. That was the reason why it did not collapse in the fire. THE GLC AND THE BLAST ANGLES
The GLC engineers, together with many other engineers, became very worried about the brittle end conditions of the floor slabs, particularly in the H2 joint. In mid 1969 they announced a programme bolting continuous steel angles underneath the floor slabs at all load bearing junctions - flank walls (H2) and cross walls (H4). They also fixed short angles on top of the floor slab and back to the wall at skirting level. This upper part of the floor, particularly in the H2 joint was the weakest part of the entire structure. An explosion would lift this H2 end of the slab and cause the other end to act as a hinge (H4 crosswall joint). This released the weight of the floor slab from the wall it was bearing on and the one above. The blast would then move the two panels out and the weight they were carrying above would then cause progressive collapse. This is what happened in Ronan Point and is what would happen in the TWA blocks in an explosion. Indeed this would happen in other LPS blocks of flats. In 1969 I wrote to Sir Hubert Bennett FRIBA, the Chief Architect & Planner at the GLC, and also to the CEO of the London Borough of Newham, to inquire why these angles were not fireproofed. I was told that because they were not carrying any load this was considered “an unnecessary expense”. David Adler and I decided to test this out. If these angles, described by the GLC as “blast angles” were not carrying any load, then it should be possible to release the nuts. Even with a sixteen stone engineer hanging on the end of a very long spanner it was impossible to loosen any nuts either in Lannoy and Hartopp or Ronan Point. What this showed was that since they were built, these buildings had settled and due to the lack of drypack and all the loads being taken as point loads on the lifting bolts, instead of uniformly distributed loads as they were designed for, then catastrophic collapse could have happened in high winds, in peak gusts of 105mph. When Ronan Point was dismantled and the bottoms of the wall panels were inspected, star shaped cracks were found around these nuts. In 1984 the BRE proposed removing 8 storeys from the top of Ronan Point to reduce the load. They also proposed removing 4 storeys from the top of the 14 storey TWA Morris Walk buildings. At a session that was held with the tenants of the Ledbury Estate one tenant mentioned this. She had no idea of the significance of what she was saying or how important it was. I had not mentioned what was proposed by the BRE at Ronan Point. Reference to Ronan Point can be found in the 1984 BRE Report: “The structure of Ronan Point and other Taylor Woodrow Anglian Buildings” page (v) para 3. CONCLUSIONS Following all the research I carried out from 1983 onwards I never expected to find all these same problems re-emerge half a lifetime later. From 1967-1971 I worked as a principal project architect in the London Borough of Camden where I designed a Section 20 building under the London Building Acts (Amendment) Act 1939. This involved taking my scheme to the District Surveyor for approval and then going to the LFB on the Thames Embankment for approval from the LFB. I never found this difficult to do, in fact I found it was a learning process. On 12 October 1984 David Adler wrote the following memo to the Assistant Borough Architect (Housing): “As structural engineer to this Council I consider that, following information coming out of the Ronan Point report (this is the BRE report attached) the tenants of Hartopp Point and Lannoy Point may be in great danger from the collapse of all or part of the buildings in certain, admittedly remote, circumstances. However, it is possible that the chances of a death occurring from this cause are greater than those from smoke penetration through the openings regarding which you are so concerned. It is therefore my considered opinion that the investigation of the flank walls to ensure ourselves that the defects are not significant must be undertaken without undue delay. Should an incident occur as a result of delay occasioned by our bureaucratic procedures we should all be held responsible. Signed: David Adler Chief Structural Engineer."
David Adler was taken off this work and moved sideways. Had H&F acted upon his advice they would not find themselves in the position they find themselves in today. In 2010 I was appointed as advisor to the families of the deceased at the Lakanal House Fire Inquest and I worked closely with Ronnie King. We both advised the legal team led by John Hendy QC and Louise Christian of Christian Khan. After the Lakanal House Inquest finished, Ronnie King asked me join the All-Party Parliamentary Fire Safety & Rescue Group as an advisor I am one of the five members of the RIBA Expert Panel set up and chaired by Jane Duncan PPRIBA following the Grenfell Tower Fire. Both Ronnie King and I, and many others, had warned that such a fire would happen if nothing was changed. I wish it had not cost 71 innocent people their lives and destroyed the lives of so many other innocent people. Sam Webb RIBA