Sourcing Traditional Materials
Sourcing and sustaining supplies of traditional materials for the maintenance and repair of historic buildings and designed landscapes.
The use of locally sourced construction materials contributes greatly to the distinctiveness and significance of many historic buildings and areas. The availability of suitable materials for maintenance and repair works is, therefore, a key aspect of heritage management. This research topic is concerned with sourcing and supplying traditional materials that are currently difficult or impossible to obtain.
Collyweston slate
Colllyweston slate roofs make an important contribution to the visual character of the towns and villages around Stamford, Lincolnshire. But production of Collyweston slates ceased in the 1960s, and suitable material for repairs or new roof coverings became increasing scarce. This resulted in the use of slates that had been ‘reclaimed’ from other roofs, or concrete replicas.
Collyweston slates were traditionally mined in December and left over winter to be split by frosts. However, since the 1960s there have been fewer cold winters frosts and this has been a major obstacle to reviving production. So we needed to find a reliable artificial method of frosting. Laboratory test were carried out at Sheffield Hallam University followed by full scale testing on site.
An industrial freezer unit was set up at Apethorpe Palace and for the best part of two years trials took place until production was achieved reliably. A Collyweston slater and miner with over 60 years experience was then hired to train contractors in the production of the slates. Slates produced in this way have now been used in a number of projects with no reports of problems. An old mine has just re-opened and the artificial frosting method is now being used commercially.
Participants: Sheffield Hallam University; Dr David Jefferson; Messenger Construction Ltd (Northampton)
Read more about this project:
Find out more about the trials
Case study on re-roofing of Apethorpe Palace and other projects
Building Stones of England
Finding suitable replacement stone for conservation repairs can be challenging. Many historic quarries have closed, and detailed information on the different types of stone used in particular localities is hard to find. But unless replacement stone matches the host material in mineral composition, density and porosity, there is the risk that it could hasten the decay of historic fabric. Also, if the replacement stone weathers differently to the original, its appearance might eventually become unsuitable.
The Building Stones of England project aims to address these problems by identifying the most important building stones in England, their historic and current sources, and representative buildings. This information is now freely available as a single resource, through a searchable GIS map, spreadsheets and guides. It enables suitable stones to be sourced, both for repair of historic building and new projects in sensitive locations.
Participants: The British Geological Study; Geckoella, local geological consultants.
Programme and progress: The Building Stones of England project is due to be completed in 2023.
Read more about this project: Building Stones of England.
Finding stone – article in volume 154 of Context, the Journal of the Institute of Historic Building Conservation, published by Cathedral Communications Ltd in May 2018.
Thatch
Thatch is a traditional roofing material in many parts of England. It has rich regional traditions that contribute to the local distinctiveness of vernacular buildings and to the character of England’s villages and countryside. Historic England encourages the use of traditional thatching materials, techniques and skills to maintain regional diversity and conserve the significance of historic buildings and areas. A key factor in this is the availability of good quality materials.
Before the mid-20th century, nearly all thatching materials were sourced locally. Since the Second World War, increasing mobility of materials and labour and more standardisation of techniques have diluted regional techniques and changed the traditional local picture. Materials, particularly water reed and timber spars, are now often imported from overseas. Moreover, there have been concerns about the quality of both indigenous and imported materials. Although there have often been bad harvests, the problems with supply run much deeper and wider than one poor year of production, and a range of adverse circumstances have left traditional thatching material production on a knife edge.
Our Traditional Thatch Project aims to support and develop the production and use of good quality indigenous thatching materials in England to secure a more predictable and consistent supply that will, in turn, support the long-term sustainability of traditional thatching.
Straw growing and durability trials
Straw has been the traditional thatching material in England for centuries, but in the late 20th century quality was variable and straw was sometimes criticised for poor performance. In 2012, we commissioned The National Thatching Straw Growers Association to undertake research into the optimum husbandry regimes for traditional thatching wheat varieties and to test the test the longevity and performance of those varieties on roofs.
The project consists of two phases. In Phase 1, growing trials of five traditional wheat varieties were carried out over two years. The growth, husbandry, harvesting and processing of the crop were monitored and evaluated. In Phase 2, the longevity of thatching straw produced in Phase 1 is being assessed on a facsimile roof.
Participants: East Anglian Master Thatchers Association; John Innes Centre; National Thatching Straw Growers Association.
Programme and progress: Phase 1 complete. Phase 2 in progress.
Read the report on Phase 1 of this project.
Issues affecting the future of traditional thatching materials
To underpin further work to support the sustainable supply of indigenous traditional thatching materials, we have undertaken research to identify the challenges facing producers. Working with numerous thatching straw growers and water reed producers, we have learned what is already being done to overcome these challenges and identified potential further steps that might be taken to increase the amount, viability and resilience of thatching material supply.
Participants: National Thatching Straw Growers Association; The Broads Reed and Sedge Cutters Association; Historic Environment Scotland; National Society of Master Thatchers Ltd and other thatching organisations; individual thatching straw growers, water reed producers and thatchers.
Read the thatching materials issues report:
Traditional Thatching Materials: Issues Affecting a Sustainable Future.
Thatching machinery research
One of the priorities highlighted in the thatching materials issues report, was the need to review the machinery and equipment currently being used by thatching straw growers and to identify ways of making thatching straw production a more efficient, safer and less labour-intensive process. This could help it to become less risky and more financially viable.
Participants: Scarlett Research Ltd; Historic Environment Scotland; individual thatching straw growers.
Read the Phase 1 report:
Machinery for Harvesting and Processing Cereal Straw for Thatching: Phase 1 Report
Next steps
Future phases of the Traditional Thatch Project will look at the sustainable supply of indigenous woodland products for thatching and the economic and legislative barriers to growing and developing suitable varieties of wheat for thatching.
