8 C O N T E X T 1 1 9 : M A Y 2 0 1 1 Periodically The tensions between conserving as much significant historic fabric as practicable while adapting a building to changing circumstances and reconciling these two potentially competing objectives is clearly demonstrated in the opening article of the latest Journal of Architectural Conservation (Vol 17, No 1, March 2011). The building in question is the Grade II* listed Middlesex Guildhall in central London, designed by JS Gibson and built 1911–13, and converted to the UK Supreme Court and opened in 2009. The architect Hugh Feilden describes the complexity of the brief in aiming to resolve issues such as public access and high security with sustainability objectives by seeking a BREEAM Excellent rating. The philosophy of approach was not without controversy. Both the Victorian Society and SAVE objected to the removal of the historic fixtures, the latter resorting at one point to judicial review. Feilden sets the project within the context of the conservation plan drafted before the briefing stage of the project, and the guidance applying at that time, PPG15. The stabilisation of ruined masonry structures is the subject of a very informative article by the conservation engineer Jon Avent. He sets out the process of initial survey to understand the behaviour of the structure, through to the implementation of the remedial works.What makes the paper particularly interesting and useful is the clear guidance on recognising the site risks; a resume of the survey techniques; elucidation of the constraints on site practices beyond normal health and safety practices; the clear illustrations; and the four excellent case studies, one each in England and Northern Ireland and two fromWales. Richard Ireland and David Gundry discuss Headford House, the last remaining house in the Republic of Ireland with a suite of interiors designed by Robert Adam. In 2004 there were sufficient concerns about the building for it to appear on the World Monument Fund’sWatch List, but once the external envelope had been conserved, attention turned to the important interiors. After a short history of the house and a description of the historical evidence from Adam’s surviving drawings, the authors explain how archaeological analysis informed the conservation process. They describe the survey work and paint analysis undertaken, and conclude by putting the significance of Headford into its wider historical and decorative context. Understanding of the project is significantly enhanced by reproduction in colour of Adam’s drawings, examples of the photomicrographs of the paint cross-sections (with explanations), and photographs of the restored interior to the sumptuous Eating Parlour. The international dimension in the journal of the development of ever more sophisticated and constantly evolving survey techniques is provided by John Smits of Corinthian Data Capture in NewYork. Smits explains how high-definition laser scanning is used as a non-invasive, non-destructive method for recording a 3D digital image of buildings. He advocates its use because of the exponential increase in its accuracy, speed and data collecting capacity over the past five years, as computing power has grown. Smits cites some good case studies and examples, and draws attention to how the technology can be used to map planar variations in ceiling and floor surfaces, and masonry facades. This can provide evidence of possible structural shifts or deterioration not apparent by traditional visual inspection and measurement methods. One example shown is a 12-storey, 49.3m-high bank building of around 1906, whose owners sought a quick and accurate way of documenting the extent of spalling and loss of bricks to the upper facade. The final paper in this issue looks at hot-lime mortar, slaking quick lime direct with sand to repair and conserve the facades of Läckö Castle in western Sweden. The castle’s present form dates from 1622–86. It is an important national monument and tourist attraction. The last major restoration of the facades took place in the 1960s. It is a rare example of this method being used in conservation practice. Ewa Sandström Malinowski and Torben Seir Hansen propound the view that hot lime could provide the key to replicating the qualities of the original lime-rich, historic mortars as the basis for making compatible contemporary mortars. The authors’ experiences of the use of hot lime mortars compared with traditional wet-slaked mortar has been encouraging. They summarise www.engineeringhistoryandheritage.com
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