The Building Conservation Directory 2024

PROTECTION & REMEDIAL TREATMENT 4.1 125 CATHEDRAL COMMUNICATIONS THE BUILDING CONSERVATION DIRECTORY 2024 DAMP TOWERS an overview LIZ LAYCOCK and MARIA-ELENA CALDERÓN RAIN PENETRATION is a problem for many buildings; it can mobilise harmful salts and support the growth of unsightly algae and biofilms that can pose health risks. As well as damaging internal surfaces, damp makes buildings cold and sometimes even unusable. Throughout the late 20th century, it had been noted that many church towers in south-west England suffered from rain penetration but that the often-costly attempts at remediation had failed to solve the problem and, in some cases, had made it worse. With the annual average rainfall for south-west England over twice that of the rest of the country (BS8104:1992), the towers were already facing challenges from the weather and they also needed to be resilient against climate change. There were clearly some common factors; many of the towers had lost their original external surface finish (the fashion for stripping masonry walls of limewash and render that began in the 1820s, spearheaded by Pugin and the Ecclesiologists, has persisted to the present day); and there were other issues such as voiding in the core of the wall, poor specification, poor workmanship and the use of inappropriate materials and techniques. However, neither causes nor best practice for remediation were clear. In 1989, English Heritage (now Historic England) initiated the Damp Towers research project to investigate these problems. The integrated programme of laboratory testing, field trials and site monitoring that followed continues to this day and is the longest on-going building conservation research project undertaken by Historic England. During the early phases of the research, the ability of lime render to reduce driving rain penetration was clearly demonstrated. However, this finding has – on the whole – failed to change the attitude and approach of many building owners and custodians who prefer the appearance of exposed masonry, and even some conservation professionals support this view. There is of course, a small minority of buildings where the masonry was not originally intended to be covered, and where applying render or limewash would unacceptably harm significance. But there is an increasing body of evidence (both documentary and from surviving building Paths by which liquid water can enter into and travel through a masonry wall. (Diagram: authors’ own) The tower of Holy Trinity Challacombe, Devon, was so damp that ferns were growing on the interior and the church was unbearably cold and damp. (Photo: Historic England) St John the Baptist, Stowford, Devon, showing the severe rain penetration common to the exposed towers under consideration. (Photo: Historic England) fabric) that the majority of solid-walled masonry buildings in the UK were either rendered or limewashed historically; for such buildings, reinstating a traditional finish is likely to bring technical benefits and restore the original appearance. As some parts of the UK are experiencing more intense rainfall