ABSTRACT
This chapter outlines the principles of Building Pathology. It provides the historical and technological background for the systematic study of building problems.
1.1.1 Problems of building failures
Most building defects are avoidable; they occur, in general, not through a lack of basic knowledge but by non-application or misapplication of it. Such knowledge seems to become mislaid from time to time. Those with long memories and those whose business it is to make a particular study of building defects are often struck by the re-emergence of problems which have been well researched and documented. Certain fundamental properties of materials, such as their ability to move through changes in temperature and moisture, seem to be overlooked and a rash of difficulties occurs. A call goes out for more research but, in truth, all that is usually needed is a good system for the retrieval of information, a better procedure for its dissemination and, most important, the realisation that a search for information is desirable. Current training in design tends to concentrate on what to do rather than
on what not to do. A similar situation exists in training in constructional techniques, where the craftsman is instructed how best to undertake a particular operation but to a lesser extent in the dangers of deviation from an accepted technique. Understanding of the likelihood of defects through inadequate design or construction is taught implicitly rather than explicitly in most built environment degree courses. The level and nature of defects in building construction currently encoun-
tered suggest that more guidance is required on the avoidance of failures.
A need is seen, too, for such guidance to be a positive part of a training curriculum. Indeed there are good arguments for suggesting that, as the first essential in design and construction is to ensure that the structure provided is stable and durable and so specific education in the avoidance of failure should be a major part of any design and construction syllabus. The purpose of this book is to provide such positive guidance in a suitably
compressed form. It does not set out to describe every possible way in which a building may become defective: such a task would scarcely be possible and certainly would not be particularly helpful. It seems better to aim at identifying the principal defects and their causes, which if wholly eliminated would prevent the great majority of the defects which currently occur, save occupants of buildings much annoyance and discomfort, and also reduce the national bill on maintenance and repair by scores and, possibly, by hundreds, of millions of pounds annually. The book aims to identify the nature and cause of important defects
occurring in buildings, with emphasis on those affecting the fabric of a building and its associated services. It does not deal with issues of aesthetics, lighting, or thermal or acoustical comfort. While concerned primarily with the avoidance of defects, the text, particularly in Chapters 2, 3 and 4, also gives guidance to aid in their correct diagnosis when, unfortunately, the situation demands cure rather than prevention. Except in a general way, the repair of such defects is not covered. Any one specific failure needs a detailed examination to decide on the most appropriate repair, for this depends not only upon technical considerations but also upon the type of building and its age, and upon related economic and social considerations. There are few standard solutions to problems of repair. Most defects occur through the effects of external agencies on building
materials, and Chapters 5 and 6 consider in some detail the nature of these and their effects on the materials commonly used in building. These agencies include the principal components of the weather, namely solar radiation, moisture and air and its solid and gaseous contaminants; biological agencies, in particular fungi and insects; ground salts and waters; and manufactured products used in conjunction with building materials, for example, calcium chloride. Moisture occupies a central role, as the villain, in many building failures (Rose 2005). The main sources of moisture and the ways in which the amounts present
may be minimised are dealt with in Chapter 7. Special emphasis is given to the cause and effects of condensation, and how the risks may be avoided or reduced. Condensation, particularly in local-authority dwellings, can truly be said to have been the greatest single cause of human discomfort in dwellings since the end of the Second World War. The elements of building structure are then dealt with, starting with foundations and progressing logically upwards to roofs and parapets, passing on the way, floors, walls, cladding and external joinery. The avoidance of defects in building services
has a chapter to itself. The book concludes with a more speculative chapter dealing with failure patterns and control. It attempts to relate defects to problems associated with the structure of the industry, to the dissemination of information and to particular difficulties which result from rapid innovation. Current control methods are outlined and a possible strategy is suggested for improving control, quality and reliability. The intention and hope is that this book will provide positive guidance to
the student designer, technologist and builder on how to diagnose and avoid the principal defects in buildings. It includes few complex scientific concepts and requires only a little special knowledge of science. Though concerned more with normal building than with major civil engineering construction, much of the text is of relevance to structural engineers also, particularly those parts dealing with the properties of the structural materials with foundations and with cladding. The point was made at the beginning that knowledge gets mislaid: a fur-
ther aim of this book is to serve as an aide-mémoire for practising designers and builders. For this reason, it has been kept concise, and is illustrated to give visual emphasis to some of the more important defects which can occur. These illustrations and parts of the text which describe the likely appearance of failures may assist surveyors and maintenance personnel, too, by steering them towards the probable cause of a failure. Though the essential aim is to avoid failure, once it has occurred and maintenance is needed, it is hoped the book will help both in identifying the cause and in preventing the adoption of the wrong remedial action. It may also help the maintenance engineer and surveyor by putting the severity of a failure and its consequences into a reasonable perspective and so prevent over-reaction to the event, which is not uncommon, particularly with foundation problems. If the book succeeds only partly in these ambitions it will, nevertheless, save both money and misery.
