Conservation compendium

James Miller, a Conservation Accredited Engineer, introduces a new series on conservation engineering by exploring the philosophy and history of the modern conservation movement, from its roots in the works of John Ruskin to the present day.

In response to the need for particular professional skills when working on heritage assets in the UK, the principal construction professions have formed schemes for accrediting those professionals in architecture, building surveying and civil and structural engineering who have the necessary skills. This article provides details on the schemes.

As structural engineering students, we learn about mild steel, modern design and construction methods. However, historic structures often do not fit into this mould. Whether you work in conservation or are a general practitioner, you are likely to come across cast iron, wrought iron, as well as early mild steel structures.

Replacement of stone on historic buildings may be required for numerous reasons. These include age-related decay and weathering, poor workmanship in terms of material choice or setting, defective fixings, and structural failure. The main aim, in assessment, will be to retain the historic fabric where practical. However, the decision to replace will depend to a great extent on having a clear understanding of the significance of the stone, both individually and within the context of the element that it is part of, its predicted life or durability and its cost.

Cantilever stone staircases have been used in all sorts of buildings for more than 350 years. Unfortunately, when surveying buildings we can be so intent on getting from floor to floor that we forget to look at the stairs on the way. Like all structures, stairs need regular inspection and maintenance; without which, collapses can ultimately occur.

Geoff Clifton describes the use of concrete as a major constituent of repair work performed on English cathedrals in the 20th century, but raises concerns about the long-term problems this use may result in.

This article looks at some aspects of floor loading and how its application has changed for the better. It encourages a careful consideration of loadings to avoid unnecessary and irreversible loss of fabric through the application of significant strengthening schemes, cutting away existing historic framing.

This article focuses on the phenomenon of 'bond timbers', which were commonly built into masonry walls from the late 17th to the early 19th century. Guidance is offered to engineers who may encounter these when working on an existing building.

This article is the first of two which will discuss the problem of corrosion of steel frames behind masonry elevations. It aims to provide an introduction to this form of construction and to consider the ways in which lack of maintenance can lead to corrosion of the steel frame, before setting out how remedial work should be approached.

This article continues from the previous instalment in the series, and aims to guide engineers in assessing the extent of corrosion of steel frames and in selecting appropriate treatment methods.

Our built heritage is a finite resource stretching back thousands of years. Protecting and conserving this heritage is a challenge requiring knowledge, skills and experience, together with an ability to bring practical engineering judgement and often creative and imaginative solutions. This paper sets out the challenges faced by engineers and some of the approaches taken in the appraisal and protection of ruins.

In this article, issues associated with the scaffolding of historic structures are briefly explored and illustrated through four case studies. These are projects that crossed the author's desk, as a consulting engineer specialising in the conservation of historic structures, within a few months of each other. They explore some of the constraints imposed by 'historic fabric' and other factors, the compromises made, and the solutions reached.

Timber and stone are the oldest known building materials. Our most ancient buildings are characterised by their use. So it is no surprise that an engineer looking after historic fabric will regularly encounter the need to repair timberwork. 

This article illustrates how structural timber fared at the Grade II listed Dunston Staiths in northeast England. 

In conservation work and like-for-like repair on older masonry, lime mortar is the only recommended material. The thick, plain or lightly punctured walls that make up most historic buildings have few concentrations of load. Calculations of stress in such cases are often needless and, subject perhaps to the check of any critical element, we can generally lay aside our concerns about mortar strength.

Historic buildings and structures, like any other, move to some degree, whether due to thermal effects, changes in moisture levels in the structural fabric, influences on the founding subsoil, or environmental forces. The key question for the conservation engineer is to determine whether the movement is progressive and presents a risk to the structure.

This article introduces engineers to the various techniques available to monitor movement in historic structures, from simple manual techniques which are less commonly used today, to sophisticated electronic systems. The form of monitoring will depend on the nature of the assumed movement, the funds available, and the possible consequences if the movement is progressive.

According to the Institution's librarians, one of the most common requests they receive is for information on structural floor systems dating from the late 19th and early 20th centuries. In particular, engineers appear to have a thirst to know more about filler-joist floors. This article describes their origin and how they perform.

This article aims to discuss some of the issues, challenges, tools and techniques available to the practising structural engineer when assessing existing structures. While the article focuses principally on floor structures, the techniques can be used on a range of applications to provide an understanding of how existing structures are actually behaving, rather than how we might think they are working.

James Miller brings this series to a close by looking back over ground covered and forward to a bright future in which conservation accreditation is increasingly valued and engineers are able to innovate through the application of emerging technologies.