Context 154 - May 2018

14 C O N T E X T 1 5 4 : M A Y 2 0 1 8 CLARA WILLETT and CHRIS WOOD Finding stone Historic England’s Strategic Stone Study’s county-by-county, nationwide survey identifies building stones used, and maps their sources and representative buildings and structures. Sourcing the right stone to conserve historic buildings can be extremely challenging. Lack of an appropriate supply is not only a matter of aesthetics but also of technical compatibility, because any new replacement stone should match the original in its mineral composi- tion and physical properties, in particular its porosity and permeability. An inappropriate new stone can accelerate the decay of the older adjacent stone and is likely to weather differentially. In addition, many new buildings and extensions, particularly those in conservation areas, will have to be constructed using materials matching those of the buildings around them. The rich diversity of England’s geology means that thousands of different stones have been used over the centuries for building. But until now accurate information on the original quarries, and the number and distribution of buildings constructed from these stones, has been elusive. The Symonds Report Planning for the Supply of Natural Building and Roofing Stone in England andWales (2004) identified the problems of sourcing appropriate stone to repair historic buildings. It recommended that a national database of the building and roofing stones be established, and that mineral planning authorities should identify and protect ‘heritage quarries’. In response to this, the Department of Communities and Local Government produced guidance for mineral planning Totternhoe Quarry, Bedfordshire. Stone, locally known as clunch, has been mined and quarried here for centuries.This important building stone can be found in historic buildings within the county and beyond. (Photo: ClaraWillett, © Historic England) Selecting replacement stone that is less permeable than the original can exacerbate deterioration of the original. (Photo: ClaraWillett , © Historic England) authorities and others by publishing Minerals Policy Statement 1 . Annex 3 on Natural Building and Roofing Stone, recommended that: ‘English Heritage and the industry are encouraged to make mineral planning authorities aware of important sources of building and