Conservinga 20th centurycollege John Preston puts forward the case for the preparation of a Conservation Plan for New Hall, Cambridge. New Hall, Cambridge was built by Chamberlin Powell and Bon from 196266, in white calcium silicate brick and concrete; the central feature is the 8leaved ferrocement dome over the Hall. The New Hall buildings were listed II* in 1993. lem was that repairs to the ring beam's inner surface (exposed in the Hall) could have resulted in ugly scars in the College's most significant space. It was only on detailed examination that the original surface was found to be a slurry finish; this will be reinstated (concealing the scars) as part of the refurCONSERVING TWENTIETH CENTURY BUILDINGS In recent years the College and its architects have been dealing with a series of structural and other issues, notably the impact of environmental health and safety requirements. These have led to a series of applications for listed building consent. Most of the structural issues have arisen from problems with original materials and/ or design details. So far, each application has had to be considered on an individual basis, with no clear overall picture or context within which to consider the wider significance of any single decision. bishment of the Generalviewof New Hall,CambridgebyChamberlin.Powell & Bon Some of the many structural issues have included: iJ Failure of the Hardrow synthetic slates (which had been laid at an inadequate pitch) on the residential blocks. Listed building consent was granted for replacement in terne coated zinc; this was visually acceptable (the pitch is so low that the roofs are barely visible from ground level) but involved an unanticipated requirement for additional lightning conductors which had some impact on the elevations. □ Rotting of the timber screens to the balconies. The original detailing was flush, with no drips orweatherings. The outcome involved a difficult balance between reinstating the original material (timber), but with the detailing altered to provide weathering, or dunging the material and reinstating the detailing. Ian Steen, the architect, argued strongly for the latter; after strong resistance from English Heritage, the approved solution involves timber balcony screens with weatherings. □ Problems with the reinforcement of the aprons supporting the ferrocement dome. Philip Cooper of Harris and Sutherland contacted the original structural engineers; their photos showing the erection of the dome were extremely helpful in assessing the problem and finding a solution. One potential prob30 Hall. The College Hall is a dramatic space, with a servety which rises directly out of the floor as its most theatrical feature; RH Partnership are the architects for major refurbishment proposals which will give it back much of its original impact. Reinstatement of the full character is compromised by the combined impact of Environmental Health and Health and Safety at Work requirements. The former require replacement of the original kitchen installation (unRepairsto ring beamin hall ·derneath the Hall), and, most problematically, provision of separate 'clean' and 'dirty' lifts between the kitchen and Hall; the original servery (which rises from the flush floor with no protective edging) seems to have no chance of complying with the latter. RHPartnership carried out a detailed analysis of the original design concept and the relative significance of its different elements. This helped guide the choice between providing new lifts within the envelope of the existing Hall (but compromising the internal space) or providing new external facilities (compromising the hermetic form of the dome and its four comer half cylinders). Listed building consent has now been granted for an external solution, with a new low-key form being added to the least conspicuous side of the dome (facing the kitchen access). RHPartnership's approach, encouraged by the Council and English Heritage, was something close to a 'mini Conservation Plan'. We have been encouraging the College to prepare a full Conservation Plan, which seems the only way to provide a sound agreed basis for an ongoing series of difficult decisions, in which they will have to make the case for changes. Problems to be tackled include the original windows in the main elevations and a major refurbishment/renewal of services. John Preston is Conservation and Design Officer, Cambridge City Council; and the !HBC Education Officer. Context65 March2000
RkJQdWJsaXNoZXIy MjgyMjA=