HT-2022-000311 & HT-2022-000254 - [2024] EWHC 3179 (TCC)

Mr Ebbatson is a structural and civil engineer at HKA who was called to give evidence on structural matters. In particular he had been instructed to address the structural issues raised by Mr Rivett. He had inspected the property on 7 October 2021. His colleague, Mr Rousakis, returned on 13 April 2023 and produced a site investigation report supported by many photographs. Mr Ebbatson recited and adopted Mr Rousakis’ observations which were supported by the photographic evidence. For the purposes of preparing his report, Mr Ebbatson had been provided with design drawings for the structure prepared by Michael Barclay Projects Ltd., consulting engineers.

It is not a criticism of Mr Ebbatson but he produced a lengthy report which addressed issues such as the cause of water ingress and some matters relating to fire safety which were not properly the matters on which there was permission to adduce his evidence. The relevance of my observation is that the bulk of the cross-examination of Mr Ebbatson addressed these issues and there was otherwise little or no challenge to his evidence and in the absence of such challenge, I accept the conclusions of Mr Ebbatson.

The primary focus of Mr Ebbatson’s evidence was on the adequacy of the existing structure to support the steel grillage, that is the steel substructure intended to support the modular units and transfer the load to the existing loadbearing walls of the Property. He noted that the steel grillage bears onto the existing structure through steel spreader beams onto the internal walls and timber ladder frames onto the perimeter walls. Mr Ebbatson produced a diagram showing and numbering the spreader beams and I adopt his numbering.

Mr Ebbatson placed particular reliance on the design standards in BS 5628, BS-EN 1996-1-1, BS-EN 1996-2 and the Institution of Structural Engineers Manual for the design of plain masonry in building structures, 2^nd ed, all concerned with safety in the design of masonry structures.

On the adequacy of the existing structure to support the steel grillage, Mr Ebbatson’s opinion was as follows:

Mr Emmett, in cross-examination, summarised this evidence, rather dismissively, as being that Mr Ebbatson had highlighted 4 beams that needed attention. Although it is fair to say that it was in respect of four beams that he identified a breach of the relevant design standards Building Regulations and of clause 5.2, the breach was a serious one which potentially affected the structural stability of the building. As Mr Ebbatson said the concern was that the shortening of the spreader beams increased the concentration of the load on the masonry walls which were more brittle and which was likely to cause at least local issues. There was no immediate concern at this stage but any risk would increase as the building aged.

I note as well that Mr Chick, who gave evidence on remedial works, is also a civil engineer of many years experience. Although it was not within the scope of this report, he was asked in cross-examination what would happen if the remedial work was not done. His answer was that the beams had introduced concentrated loads on the masonry below. Over time the masonry would tend to fracture which would reduce their ability to bear the load leading to a local failure in the masonry. That was entirely consistent with Mr Ebbatson’s evidence.

I am satisfied that there are breaches of the FPA in respect of these beams and any beams that were not adequately packed and that these give rise to a relevant liability for the purpose of the Building Safety Act 2022. It does not seem to me that it would be right not to so characterise a failure to comply with design standards concerned with structural safety on the grounds that the risk has not yet manifested itself and may not do so and is capable of being addressed. That is the nature of risk and that is what the “relevant liability” is concerned with. It also follows that these matters amounted to a breach, or placed Click St Andrews in breach, of the covenant of quiet enjoyment.

The Particulars of Claim also included a specific allegation that the modular units were not properly aligned to the sub-frame such that one of them was not properly supported and was unstable. Mr Levenstein repeated this allegation of breach in Opening Submissions. In Closing Submissions he submitted that the rooftop flats were not level and gave as the relevant evidential reference Mr Rivett’s condition report on flat 17 dated 22 February 2023. I have already observed that, in his first report, Mr Rivett noted that, at the time of his inspection, the modular units were not properly aligned and were being levered into alignment. In the condition report on flat 17, he noted that the floor of the kitchen, dining and hall areas sloped and said that he “suspected” that that was because the modular units were not properly aligned. He advised that the structural support and alignment issues should be checked by a structural engineer. However, Mr Ebbatson, in his report and evidence, said nothing about alignment. The high point of this allegation is, therefore, Mr Rivett’s suspicion. I do not consider that sufficient for me to conclude, on the balance of probabilities, that one or more of the units are not properly aligned. Having said that, it would not seem to impact the claim for damages as there is no distinct claim for remedial works in this respect.

A further specific issue relied on by the claimants and addressed by Mr Ebbatson was compliance with the Building Regulations in respect of disproportionate collapse, that is a collapse that occurs in a building when the failure of one component leads to the failure of a series of other components. Requirement A3 in Approved Document A states that “The building shall be constructed so that in the event of an accident the building will not suffer collapse to an extent disproportionate to the cause.”

The Approved Document at Table 11 sets out different Building consequence classes for which different levels of robustness are required. In the present case, the addition of a further storey took the building from class 2a to class 2b. Mr Ebbatson identified that two alternative approaches might be applicable to a penthouse extension of this nature. One is the incorporation of a strong floor above the roof of the existing building designed to act as a crash deck unless it can be demonstrated that an impact from the collapse of the penthouse structure does not need to be accounted for. The other is to demonstrate that the extension is only marginally more unsatisfactory than before. Each of these strategies needs to be agreed with the local authority.

In this case, the grillage was designed to conform with class 2b. Ties were designed to deal with transfer to the steel grillage. From Mr Ebbatson’s review, no consideration had been given to the load from falling debris but he said that the penthouse structure was not likely to collapse onto the existing structure due to loss of support and thus the steel grillage did not have to be designed to resist an impact load arising from falling debris. Further the design had not been implemented to accommodate tying forces in satisfaction of the disproportionate collapse requirements. As he said, that did not mean that the modules could not accommodate the tying forces but that it needed to be proved by calculation. In other words these are the matters referred to in the quotation above from the report. In any case, the disproportionate collapse strategy had to be agreed with the local authority and he was not aware that it had been.

Mr Ebbatson’s conclusion in his report was that the disproportionate collapse strategy was acceptable provided it conformed to the A3 requirement in respect of consequence class 2b. That seems to me to say nothing and certainly not that it did not conform. Referring to the earlier part of his report, it appears to be a reference back to the fact that the grillage was unlikely to be impacted by falling debris and Mr Ebbatson added that that confirmation was required from the local authority.

In cross-examination, Mr Ebbatson agreed that the detailing of the design (in terms of the disproportionate collapse strategy) was adequate. He said that he had seen nothing to show that it was agreed with the local authority but that that was a technical non-conformance.

On the basis of this evidence, I am unable to conclude that there was any breach in respect of the disproportionate collapse strategy. If I am wrong about that on the basis that there was no agreement with the local authority, the remedy is reaching that agreement and there is no basis on which I could find that the strategy was not adequate and that remedial works were required. Whether that might be the case is speculation.