Patrick Robson
Review of Structural Appraisal of Traditional Buildings as published in the Journal of Architectural Conservation
It is axiomatic that successful building conservation demands understanding of the various forms and materials of construction, and awareness of the symptoms and causes of defects to which they are liable (not least 'bodging', during or after construction). These must be complemented by investigation methods yielding the facts to allow a reliable diagnosis. This logical approach, persuasively argued here, applies equally to any type or age of building that does not (and maybe never will) attract the conservator. All buildings need to be looked after, work that occupies about half of the building industry's capacity.
The traditional buildings considered are those of timber and masonry construction in the UK, from medieval times to the present day. Modern steel and concrete structures are accordingly excluded, although concrete used in foundations and ground-bearing slabs is considered. The focus is mainly on domestic construction, with some mention of other building types including early nineteenth-century industrial buildings using cast iron.
This book takes a much broader view of the term 'structural appraisal' than may be found in more numerically-based texts written principally for engineers, regarding it as the informed examination of a traditional building structure so as to understand its construction, identify defects, and diagnose their causes. It offers a good grounding to architects, surveyors, builders, and indeed structural engineers with little experience of such buildings. Repairs are not covered, for the good reason that Mr Robson has already written Structural Repair of Traditional Buildings (Donhead, 1999).
The text is in five parts of roughly equal length. The first provides an introduction to structural appraisal, with a useful outline of structural behaviour (no mathematics!) and a review of the development of building forms and materials. The second part looks at causes of damage, such as wind and snow, poorly-conceived construction and ill-judged alterations, movements due to temperature and moisture changes, decay, and ground movement.
The third part describes various investigation techniques. Documentary sources such as maps and aerial photos, and study of the building's surroundings, often reveal factors that help to explain the causes of problems. Investigations should then build up a thorough picture of the symptoms. The fourth part addresses the diagnosis, with a lengthy table of causes and their various clues - from visual to the results of opening-up and distortion surveys.
The final part focuses on particular problems: buildings founded on 'lively' clay; sudden events such as vehicle impact, gas explosion, and fire; and - in this increasingly-litigious world - issues of liability, stressing the importance of agreeing a clear brief and careful wording when reporting. A useful glossary is followed by a list for further reading, a bibliography and index.
Numerous examples are given of the often quite 'casual' way in which traditional buildings have been put together (but usually still stand up), such as stacked half-bricks comprising the flimsy structural core of a bay window mullion, evident only after thick render and plaster had been removed.
This book first appeared from another publisher in 1991. This second edition can justly claim to be 'revised and expanded', being nearly double the length and now with photographs (as well as line drawings), vividly illustrating what can go wrong. While not written specifically for building conservators, there is much here that will inform and stimulate the study and care of traditional building structures, even by non-engineers - who should, at least, then be better able to understand the issues, and also (importantly) to recognise when specialist advice is needed.
Michael Bussell
Building and Structural Engineering Consultant, London
Structural Appraisal of Traditional Buildings
