Search results

The techniques available for the repair of historic masonry structures are extremely wide ranging. The advantages and disadvantages of each type of repair can be evaluated in terms of cost, time and quality as with modern projects. It is however, important to realise that when repairs to historic buildings are selected they must conform to building conservation philosophy, or an ethical and principle based evaluation. The purpose of this paper (part 2 of 2) is to establish what is meant by principles in this context and wherever possible apply practical examples to illustrate these concepts.

Evaluative literature review of the principles encapsulated within building conservation philosophy utilising them to stimulate discussion on practical repair interventions.

It has been shown that the principles of building conservation philosophy must be considered prior to making decisions relating to masonry repair. These repairs have varying degrees of defensibility, and will ultimately lead to good or bad conservation approaches. This paper briefly discusses the principles, highlighting some of the issues that may be initially confusing to the practitioner.

The evaluation of building conservation philosophy for masonry repair, and more specifically the “principles” have been little studied. The importance of this cannot however be over stated, as far from being an esoteric concept it affects every practical repair. This work brings together the study of the philosophical and practical, enabling practitioners to better understand the ramifications of building conservation philosophy for their projects. It must however be emphasised that as with any aspect of philosophy, there is not necessarily a right or wrong answer, only higher levels of defence for the selected repairs.

Sustainability is well understood to encapsulate economic, environmental and societal parameters. The efficiency of maintenance interventions for historic buildings is no exception and also conforms to these broad factors. Recently, environmental considerations for masonry repair have become increasingly important and this work supports this growing area. The purpose of this paper is to give insight on how an option appraisal approach of “Green Maintenance” modelling for historic masonry buildings repair practically determine and ultimately substantiate the decision-making process using a calculation procedures of life cycle assessment, within delineated boundaries.

Calculation procedures of the model enables an assessment of embodied carbon that is expended from different stone masonry wall repair techniques and scenarios for historic masonry buildings during the maintenance phase.

It recognises the importance roles Green Maintenance model can play in reducing carbon emissions and underpins rational decision making for repair selection.

It must be emphasised that the calculation procedures presented here, is not confined to historic masonry buildings and can be applied to any repair types and building form. The decisions made as a result of the utilisation of this model practically support environmentally focused conservation decisions.

The implementation of the model highlights the efficacy of repairs that may be adopted.

The paper is a rigorous application and testing of the Green Maintenance model. The model relays the “true” carbon cost of repairs contextualised within the longevity of the materials and its embodied carbon that consequently allows rational appraisal of repair and maintenance options.

The assessment of a deteriorating masonry structure should lead to an objective evaluation of condition. This process is, however, inevitably subjective owing to human interpretation. The condition of the substrate and the required repairs cannot be guaranteed and may vary from building inspector to inspector. For conservation works the determination of repairs is a function of condition but also directly relates to the underpinning framework of building conservation philosophy. These are also fundamentally subjective. The combination of both condition survey subjectivity and building conservation philosophy's nebulous nature creates the potential for project aesthetic and technical divergence. This paper aims to examine this issue.

The paper presents a literature review and hypothetical case studies.

It has been shown by various researchers that a visual survey is subjective and is therefore prone to differences in reporting. In addition, the application of building conservation philosophy is seen through the perspective of the professional specifying the repairs. The combination of these two factors leads to the potential for significant project outcomes.

Subjectivity of evaluation of condition for traditional masonry structures has been little studied by academics and practitioners alike, and it is generally assumed that these yield objective, rational data. This is not necessarily the case. The application of building conservation philosophy to determine repair strategies is also a subjective process. The combination of both may lead to significant project divergence. These combined factors have never previously been discussed.

The techniques available for the repair of historic masonry structures are extremely wide ranging. The advantages and disadvantages of each type of repair can be evaluated in terms of cost, time and quality as with modern projects. It is however, important to realise that when repairs to historic buildings are selected they must conform to building conservation philosophy, or an ethical and principle based evaluation. This paper (part 1 of 2) aims to establish what is meant by ethics in this context and wherever possible seeks to apply practical examples to these concepts.

The paper takes the form of an evaluative literature review of the ethics encapsulated within building conservation philosophy utilising them to stimulate discussion on practical repair interventions.

It is shown that ethical considerations are of prime importance for decisions relating to masonry repairs. These repairs have varying degrees of defensibility, and will ultimately lead to good or bad conservation approaches. The paper briefly discusses the ethics, highlighting some of the issues that may be initially confusing to the practitioner.

It must be emphasised that as with any aspect of philosophy, there is not necessarily a right or wrong answer, only higher levels of defence for the selected repairs.

The evaluation of building conservation philosophy and more specifically, ethical considerations for masonry repair has been little studied. The importance of this undervalued aspect of building conservation cannot be over emphasised and far from being an esoteric concept, it affects every practical repair. This paper brings together the study of the philosophical and practical, enabling practitioners to better understand the implications of building conservation philosophy on their projects.

The purpose of this paper is to address the issue of perceptions of suitability of different materials for a repair. The use of highly cementitious materials in the repair of historic masonry is causing great concern due to their incompatibility with adjacent stone and the associated accelerated deterioration which results from their use. The relatively recent development of so‐called “restoration mortars” based on a “mix and go” application, combined with the enhanced weathering of stone in a changing climate, may be contributing to the use of “plastic” repair materials on stone across Scotland.

Following a literature review, case studies of repairs are presented to highlight the advantages and disadvantages of using such materials, and comparisons are made with the alternative options.

The case studies presented highlight the use of a number of different stone repair materials, sometimes in combination with stone replacement, representing functional and philosophical approaches to masonry repair. However, the research has also highlighted the increasing use of plastic repairs for large‐scale repair including façade rendering, which fail to incorporate these systematic and informed approaches, and can ultimately lead to failure of repairs.

An evaluation of the current standing of the materials, methods and the extent of this type of repair, is vital for the substantiation of further research, and to enhance the empirical knowledge of in‐use performance, longevity and failure. The increasing emergence of restoration mortars, and their manufacture and supply on an international scale, highlights the global impact and relevance of this research.

The selection of lime mortars for masonry structures can be an important component of a repair or new build project. This selection is considered difficult due to the number of variables to consider during the decision‐making process and the perceived inherent complexity of the materials. The purpose of this paper is to discuss the selection process for determining suitable natural hydraulic lime repair mortars for masonry.

The paper presents a conceptual and practical framework for the determination of suitable lime mortars for repair and construction of masonry structures, drawing and building on relevant, literature and existing best practice guidance on specification.

The use of various relatively newly produced data sets pertaining to durability can aid in the appropriate selection of lime mortars. These determinants must however, be correlated with traditional evaluation of exposure levels, building detailing and moisture handling performance. Building condition survey of the existing fabric is essential to enable refinement of the selection process of these mortars. The adjustment of the initially identified mortars highlighted in the best practice guide may potentially benefit from modification based on the aforementioned factors.

Whilst data exist to help the practitioner select hydraulic lime mortars they have never been correlated with the tacit and expressed protocols for survey and the evaluation of the performance of structures.

Outlines the current processes and materials used in the cleaning of historic stonework, giving a broad background to the situation as it stands at present. Discusses the reasons behind decisions to clean, highlighting aesthetics and damage monitoring. Provides an account of essential steps to take when cleaning historic masonry, and continues with an analysis of the inspection procedure, on‐site trials and specification. Explores available cleaning methods based on water, chemicals and abrasives, and describes the damage which can be caused by each with particular reference to limestone. Gives tips on the safe use of cleaning processes, as controlled by the Health and Safety at Work Act 1974, and suggests the use of small‐scale cleaning systems new to the general cleaning market in future.

Low carbon repair epitomises sustainable maintenance management for heritage buildings. However, there is little recognition of this aspect, coupled with impractical assessment of repair impact strategies. This paper aims to present a decision-making process based on life cycle assessment (LCA) approach of lime plaster repair options for heritage buildings.

Calculation procedures of LCA were carried out to enable sustainable maintenance management appraisal for heritage buildings upon embodied carbon expenditure expended from lime plaster repair during the maintenance phase.

Calculation procedures could be understood as a carbon LCA of lime plaster repair and recognised in reducing CO₂ emissions. This underpins low carbon of lime plaster repair in achieving sustainable maintenance management of heritage buildings.

It must be emphasised that the LCA approach is not limited to heritage buildings and can be applied to any repair types, materials used and building forms. This supports environmentally focused economies and promotes sustainable maintenance management solutions.

The LCA approach highlights the efficiency of repair impact strategies through evaluation of low carbon repairs options.

The LCA approach results show that low carbon repair, contextualised within maintenance management, relays the “true” embodied carbon expenditure and stimulates sustainable development of heritage buildings.

The purpose of this research is to highlight issues relating to binder migration in traditional lime mortars and the potential consequences of this phenomenon. The paper focuses on traditional mass masonry construction and will be of special interest to those surveying, maintaining and repairing historic ruinous structures and heavily exposed masonry bridges.

The paper draws on literature pertaining to the repair of traditional mass masonry structures and the somewhat limited science of binder dissolution and migration in saturated conditions. The paper also draws on the author's practical and academic knowledge of writing specifications for the repair of mass masonry structures and utilises examples of binder migration from several case study buildings.

The degree to which binder migration in traditional mortars occurs is little understood. It is, however, evident that migration of the binder occurs when saturated conditions are present and is exacerbated by prolonged moisture ingress. The effect of binder migration on the stability and performance of mass masonry structures is also little understood and requires greater attention. In addition, the nature of the repair mortars specified and the degree to which these materials have set will have a bearing on the potential for binder migration.

An assessment of binder migration in traditional lime mortars and its effect on the stability and performance of mass masonry structures has never previously been undertaken. This paper is the first to highlight the problem.

Scotland’s built heritage (pre-1919 building stock) is exhibiting varying levels of disrepair, in particular for stonemasonry works, despite the government’s on-going efforts for promoting higher standards of repair and maintenance (R & M) of historic buildings. The purpose of this paper is to examine the problems associated with the R & M of historic buildings.

Two case studies (Projects A and B) exhibiting critical disrepair are reported. Site surveying was carried-out on both projects, to identify site features and R & M problems along with proposed solutions drawing on the lead author’s extensive industry experience as a stonemasonry consultant. Three semi-structured interviews were conducted with professionals involved in each project to elicit views on the challenges faced. Additionally, three industry experts were interviewed to provide a wider perspective of the R & M challenges facing historic buildings.

Neglect and poor practice resulted in both projects becoming more challenging and expensive than they needed to be, which was attributed to generic and advanced skills 6deficiencies of the workforce. There is an urgent need for a multi-disciplinary approach to the development of a method statement for R & M, drawing on the expertise of professionals and contractors, particularly when specifying repairs to structural elements.

This paper has provided original and valuable information on R & M problems, highlighting the importance of continued investment in skills development for historic building R & M to enhance existing current training provision and practice. There is a need for further similar project-based data to inform skills development strategies for the R & M of historic buildings as well as enhancing existing qualification frameworks.