Context 164 - May 2020

C O N T E X T 1 6 4 : M A Y 2 0 2 0 11 The war on damp Editorial It started with a blocked gutter The IHBC’s position statement on Sustainability and Conservation of the Built Environment, published in April 2020, highlights the inherent sustainability of conserving old buildings due to the retention of the energy embodied in their fabric and the carbon they contain. ‘Maintenance and repair,’ it states, ‘are fundamental to longevity.’ Aside from any considerations of significance and value, the maintenance and repair of historic fabric is at the heart of all conservation work. Damp, the theme of this issue of Context , is arguably the principal villain in the piece. Salts mobilised by water ingress can cause masonry surfaces to disintegrate. Frost expansion has a similar effect where masonry is saturated. Moisture penetration may cause hidden metal cramps to rust, cracking the masonry. And by excludingmoisture we prevent all forms of insect and fungal activity fromdamaging structural timbers, joinery, textiles and other natural components. Even seemingly inert materials such as stained glass can be destroyed by organic growth where condensation is a problem. But by no means is all maintenance and repair work conservation. An entire industry has emerged making money from the incorrect diagnosis of damp, from the replacement of damaged components that could have been repaired, and from supplying new products and services that may only work in the short term. To be considered conservation, the long-term effects of a repair or maintenance strategy must be understood, underpinned by science. This is a field that is constantly evolving as new technology emerges or as new information is discovered about practices. Soki Rhee-Duverne outlines research being carried out at Oxford University for Historic England into the various methods of measuring moisture content of porous building materials. For decades the go-to device for free damp surveys was the resistivity meter. It was cheap, quick to use and scientific-looking, and it could almost always be used to justify damp treatment. Nevertheless, in laboratory tests these and a variety of more recent non-destructive technologies were all found to give good, semi-quantitative estimates of moisture levels, provided that they were used appropriately, taking into account their shortcomings. Repair and maintenance is also the focus of Kinlay Laidlaw’s article on conserving the Burns Monument, and of Matthew Slocombe’s on curated decay, a philosophical approach that is not entirely at odds with the SPAB’s. Robyn Pender’s article, on the other hand, looks at how we heat historic buildings. From a perspective of sustainability, it is not only the embodied carbon of historic buildings that is dependent on proper repair andmaintenance. As the IHBC’s position statement makes clear, ‘poor maintenance not only hastens the demise of buildings, it also makes them less comfortable and causes users to consume more energy, for example to combat draughty windows and walls made damp by blocked gutters or leaking roofs. Repair is a fundamental consideration in improving energy efficiency.’ THE WAR ON DAMP Opposite: Tell-tale evidence of a blocked gutter: the consequences of rainwater trickling down through the wall structure behind are likely to extend far beyond the decay of roof and floor timbers (Photo: Jonathan Taylor)