The claim that the Commonwealth Institute's existing drainpipes are 'probably a bit too small' (AJ 13.7.06) would appear to be a bit of an understatement. The Arup report states that, as part of Avery Associates' replacement roof works, 'modifications were made to the roof drainage arrangement. These included increasing the size and number of drainage outlets. However, the original pipework, which is cast into the roof support columns, limits the capacity of the revised system. The drainage ow capacity of the revised arrangement has been assessed to be 21.4 litres/sec, corresponding to a rainfall intensity of 60mm/hr. . . well below both a minimum criterion for any building and an appropriate criterion for an exhibition building. The return period for an event of 60mm/hr is only 8 months.' The minimum design standard for drainage in any building today would be 179mm/hr. How puzzling, then, that Avery's 'simple and cheap solution' to the rainwater disposal problems was not implemented at the time of re-roofing.
Backing-up of the rainwater system is indeed part of the problem. As for the sensors and alarms, these will only signal that ooding is imminent: apart from standing by with buckets and mops, there is nothing the building users can do.
English Heritage's claim, after their brief visit in August 2005, that the building was 'weatherproof and watertight' is baffling. Several times during that summer, parts of the building ooded during ash storms (see pictures, above). The Twentieth Century Society's implication that the Institute did not look after the executed work also bafes. How is a building owner supposed to 'look after' a building which has been the subject of major remedial works and yet continues to ood?
I would like to emphasise that I have always given credit to Avery Associates' skilful re-roofing of the exhibition hall. But rainwater still penetrates the building - just one of many problems.
Your article could be read as implying that I am a 'supporter' of the move to de-list through legislation. As a member of an earlier working party which studied current listed building legislation I have never expressed a view on the appropriateness of either the subsequent de-listing application or the latest proposal of a parliamentary bill. My concern has been to try to place this unusual building in a historical and technical context so that the root causes and implications of its crippling defects can be better understood.
Finally, your readers may be interested to know that the building was an economic failure as a conference and exhibition centre; the subject of three failed Millennium and Lottery bids; and, in a year-long marketing exercise in 2003, attracted not a single credible purchaser intending to use and operate the building.
Peter Carolin, by email