Journal of Architectural Conservation
Volume 9 Number 1 March 2003
The Characteristics and Properties of Rubbing Bricks used for Gauged Brickwork Part One Gerard Lynch and Sara Pavia
Raindrops Keep Falling on my Lead Geoffrey C. Allen, Leon Black, Philip D. Forshaw, and Nigel J. Seeley
The Belfast Roof Truss Worth Conserving? Raymond Gilfillan and Stephen Gilbert
Sustainability and the Holistic Approach to the Conservation of Historic Cities Dennis Rodwell
Cultural Continuity and Meaning of Place: An Approach to Sustaining Historic Cities of the Islamicate World Noha Nasser
With the recent publication in England of the State of the Historic Environment Report 2002 (English Heritage, November 2002) comes a number of clear messages and searching questions. Of the 'possible headline indicators for future years', none are perhaps more important for this nation's historic environment than those dealing with investment, employment, education, and social involvement.
Papers within this issue of the Journal of Architectural Conservation provide coverage of a number of these and other such pressing matters, and offer practical guidance and wisdom in searching for often illusive answers.
Cultural Continuity and Meaning of Place: An Approach to Sustaining Historic Cities of the Islamicate World by Dr Noha Nasser offers a review of the inherent qualities that have sustained historic urban centres in the Islamicate world. This paper highlights the fact that notions of community, development, cultural heritage, and the physical environment have historically been united under the guidance of a cultural framework, and that regeneration needs to focus on empowering communities to shape their own 'envisioned realities'.
In his second paper Sustainability and the Holistic Approach to the Conservation of Historic Cities Dennis Rodwell poses the questions of how sustainable development and urban conservation relate one to the other, and how they can they be brought together in a common approach. Weaknesses in the current philosophy and practice of urban conservation and limitations on the achievement of good practice are highlighted. The author ends with a powerful and thought-provoking statement architectural conservation will continue to under-achieve until it integrates with and becomes a driving force in sustainable development.
Knowing the threats and challenges that face the historic environment, and understanding that places die if change is mismanaged, forms the key to future decision making, policy, and practice. In The Risk Map of Italian Cultural Heritage, Professor Giorgio Accardo, Dr Elisabetta Giani, and Professor Annamaria Giovagnoli of the Istituto Centrale per il Restauro in Rome introduce and describe the development of the Risk Map and point to ways in which it will assist in the future management and protection of Italy's own historic environment.
Turning to one particular risk factor, Raindrops Keep Falling on My Lead by Professor Geoffrey Allen and co-authors provides a fascinating study of patination and underside condensation corrosion as it affects sheet lead. In this and of particular importance to those responsible for the repair, maintenance, and detailing of leadwork on historic buildings is advice on how one might reduce underside lead corrosion in the future.
With the acknowledged shortage of skilled and specialized crafts people, it is all the more important that those able to impart knowledge and experience learnt on the tools be given a platform from which to do so. It is therefore gratifying to include The Characteristics and Properties of Rubbing Bricks used for Gauged Brickwork Part One by Gerard Lynch and Dr Sara Pavia in this issue of the Journal. As a master bricklayer and historic brickwork consultant, Gerard Lynch is known to many in the United Kingdom and abroad for this lectures and training events held at the Weald & Downland Open Air Museum and elsewhere.
The Characteristics and Properties of Rubbing Bricks
used for Gauged Brickwork Part One
This paper, presented in two parts, investigates the historical background, characteristics, and use of rubbing bricks for gauged brickwork. The work examines the use of low-fired bricks that do not develop a protective fireskin and which are capable of being cut through to varying depths. Such bricks, referred to as 'rubbing bricks' or 'rubbers', have been traditionally selected for use on 'cut and rubbed' and 'gauged brickwork'. Despite their softness and absence of a protective fireskin, they are extremely durable. It has, however, been observed that, once laid, the surface of rubbing bricks hardens over time. This phenomenon is discussed and, in the second part of the paper, the properties and mineralogical composition of rubbing bricks are described in order to understand their weathering characteristics.
Gerard Lynch LCG, CertEd, MA (Dist)
Gerard Lynch is a self-employed historic brickwork consultant, master bricklayer, and author.
Dr Sara Pavia graduated in earth sciences and completed her PhD in the decay and conservation of building materials at the University of Zaragoza, Spain.
Raindrops Keep Falling on My Lead
Geoffrey C. Allen, Leon Black, Philip D. Forshaw, and Nigel J. Seeley
Lead is used widely in the United Kingdom on both modern and historic buildings. It is regarded by architects as a traditional, durable material. Lead roofs are, however, susceptible to failure by condensation corrosion, the incidence of which has increased in recent years. Laboratory studies have investigated the patination of lead when exposed to present-day environments and underside condensation corrosion conditions. Factors influencing the chemical and physical properties of the patinas in both situations are discussed.
Geoffrey C. Allen BSc, PhD, DSc, CChem, FRSC
Geoffrey Allen is Professor of Materials Science and Director of the IAC. His research focuses on the physics and chemistry of materials, including surface science, oxidation and corrosion studies, interfacial reactions and wear-resistant coatings.
Leon Black gained both his BSc in Chemistry and PhD in Materials Science at the University of Bristol. He is based in Germany at the Institute for Technical Chemistry, Water and Geotechnology, Technical Mineralogy, Forschungszentrum, Karlsruhe, researching the structural and degradation properties of cements.
Philip Forshaw gained both his BSc in physics and PhD at the Interface Analysis Centre, Bristol University, the latter with a thesis based upon the work described above.
Nigel Seeley is an inorganic chemist who worked first as a forensic scientist, then became Head of the Department of Conservation at University College London Institute of Archaeology, and was until recently Head of Conservation at the National Trust. He is now an independent consultant,specializing in the scientific investigation of the technology, deterioration and conservation of historic materials.
The Interface Analysis Centre was set up at Bristol University in 1990 to study the chemical and physical reactions that occur on the uppermost surface layers of materials. Investigations have included the corrosion of metals, such as lead, aluminium and steel, and the weathering of limestones and sandstones, particularly when exposed to corrosive environments. Other studies have ranged from historic artefacts to printed circuit boards and modern electronic materials.
The 'Belfast' Roof Truss Worth Conserving?
Raymond Gilfillan and Stephen Gilbert
Timber trusses have been used in many forms since ancient times. The 'Belfast' timber truss was developed around the mid-nineteenth century to meet the demand for efficient, lightweight and longer span roofs, brought about by the industrial revolution. It is a very efficient structural form with a curved top member that behaves essentially as an arch in combination with a horizontal tie member. Several thousand still exist, many in buildings of historic interest. This paper outlines the development of this truss type, explains why it is an efficient structure and demonstrates that trusses can be replicated in historic buildings almost exactly as the original. This is supported by comparisons of the actual and the theoretical load-carrying behaviour, based on the results obtained from new trusses, tested in laboratory conditions and on trusses tested in existing buildings. In addition, the findings in a report of load tests on prototype trusses in 1906 have been included in the comparative study. All the work on the analysis, design, fabrication and testing of 'Belfast' trusses has resulted in a better understanding of their behaviour which is not only of historic interest but also fundamental to the repair and restoration of existing trusses. As well as their significance in historic building conservation the paper proposes that 'Belfast' trusses are an attractive alternative to other roof structural types.
Raymond Gilfillan BSc, PhD, FIWSC, RSUA
Raymond Gilfillan is a senior lecturer in the School of Architecture at Queen's University, Belfast. He has been engaged in structural timber research and timber engineering design for some 20 years. In addition to design of new structures, he has been involved in the assessment and repair of existing timber structures, many in buildings of historic interest.
Stephen Gilbert is a senior lecturer in the School of Civil Engineering at Queen's University, Belfast. One of his main research interests is the behaviour of timber structures.
Sustainability and the Holistic Approach to the Conservation of Historic Cities
Sustainable development is one of the core agendas of our time. It is a concept that has gathered momentum over the past decade. Urban conservation is a concept that has been with us since at least the 1960s. How do these two concepts relate to each other? How can they be brought together in a common philosophy and practice? This paper aims to summarize weaknesses in current philosophy and practice in urban conservation; to set out the relationship between successful architectural conservation and wider agendas of sustainability and cultural identity; to highlight the communality of approach and practice that needs to be fostered and developed between a complex range of interrelated issues and disciplines; and to extend both the perceived relevance of architectural conservation and its level of attainment. This paper is based upon the author's work in the United Kingdom and in continental Europe, East and West.
Dennis Rodwell MA, DipArch(Cantab), DipFrench(Open), RIBA, FRIAS, FSA Scot, FRSA, IHBC
Dennis Rodwell is a consultant to the Division of Cultural Heritage and to the World Heritage Centre, UNESCO, Paris.
Cultural Continuity and Meaning of Place
An Approach to Sustaining Historic Cities of the Islamicate World
This paper reviews the inherent qualities that have sustained historic urban centres in the Islamicate world, drawing on the historical processes of interaction between culture and the urban environment. It shows that, historically, notions of community, development, cultural heritage, and the physical environment were united under the guidance of a cultural framework. The synthesis of cultural values in the contemporary planning, conservation, and regeneration of historic centres in the Islamicate world is the key to reviving the meaning of these places and to ensuring their continuity.
Noha Nasser BSc Arch, PhD
Dr Noha Nasser is an architect interested in the conservation and regeneration of Islamicate cities according to cultural determinants and urban design principles.
Donhead Publishing 2013