C O N T E X T 1 3 9 : M A Y 2 0 1 5 5 Periodically The latest issue of the Institution of Civil Engineers Proceedings on Engineering History and Heritage (Vol 168, issue EH1, February 2015) presents three papers from different research groups concerning robust engineering processes required to answer questions of structural decay caused by increased environmental loading. The papers explore different structural materials and types, and widely different levels of exposure. They explain differing techniques of assessment, ranging from on-site monitoring, to numerical modelling and the microscopic analysis of materials. The first paper, by a team at University College London, involves a traditional timber-framed and brick infill 16th-century building in Tewksbury (a town not unfamiliar with the problems of flooding), and the lessons to be learned from monitoring internal variations in temperature and moisture over a 12-month period. The team used dynamic vapour sorption (DVS) to determine how hygrothermal damage might occur with a resulting loss of strength and physical integrity of the structure. By measuring the temperature and relative humidity at the external surface and within the thickness of the walls, the temperature gradients show that micro-cracking can occur. This leads in turn to the uptake of moisture and water penetration. The conclusion reached is that tests should be undertaken before the installation of dry-lining where the prevention of heat loss is desired, as the insulation material can substantially alter the temperature profile within the wall, increasing both moisture movement and relative humidity, and therefore the risk of fungal attack. The second paper looks at vernacular Scottish mud-wall construction and its vulnerability to water penetration and freeze-thaw cycles. Examples in and around Errol in the Carse of Gowrie were selected, as this represents the greatest regional concentration of such buildings. Two representative case studies demonstrate the typical issues that can be encountered and how the monitoring of each building was undertaken, with reference to climate models, current weather data and the local climatic context. Temperature and humidity data were collected from within the walls for a year from April 2012 (during which the area experienced a range of extreme weather events). The data collection and analysis has enabled some conclusions to be drawn about the potential impact of climate change and the formulation of recommendations on how an integrated approach to the analysis of other historic mud-wall structures can be achieved. The third paper looks at buildings in the much more extreme environment at the Prince of Wales Fort, Manitoba, northern Canada. Originally built to secure the fur trade, the surviving 18th-century masonry walls were partially frozen for much of the year when built, but recent climate change has raised average yearly temperatures. Consequently the pattern of freezethaw cycles has altered significantly, resulting in a breakdown of the mortar within the stonework; washout from melting snow and rain; and lateral deformation of some sections of the walls and collapse of others. Micromodelling techniques were employed to assess the in situ condition of the damaged walls, and establish the general susceptibility of such historic fortifications to failure due to changing environmental conditions that practicing engineers should be aware of. The latest ASCHB Transactions (Vol 37, 2014 [sic]) has six major papers, all of which are of interest and well illustrated in colour. They start with an exposition of the recent repair and refurbishment of Harvey Court, Gonville and Caius College, Cambridge, listed Grade II* in 1993. Matthew Goulcher of Levitt Bernstein describes works that began by addressing pre-existing defects and water leaks, and widened to include modernisation of the student accommodation, and better security and access. Harvey Court is considered to be a seminal late 20th-century collegiate building, noticeably influenced by the work of Alvar Alto. When designed by Sir Leslie Martin and Colin St John Wilson in 1960–62, the building form reinvented the traditional Oxbridge transactions volume 37 for 2014 ASSOCIATION FOR STUDIES IN THE CONSERVATION OF HISTORIC BUILDINGS
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