Sourcing Traditional Materials
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 tradition materials that are currently difficult or impossible to obtain.
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 or best part of 2 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:
Strategic Stone Study
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 Strategic Stone Study 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 web portal that contains a searchable GIS map, spreadsheets and county atlases (see below). It enables suitable stones to be sourced, both for repair of historic building and new projects in sensitive locations.
Participants: The British Geological Society; local geological consultants.
Programme and progress: The Strategic Stone Study is currently 80% complete and work is continuing to provide nationwide coverage.
Read more about this project:
Strategic Stone Study database
Straw has been the traditional thatching material in England for centuries, but recently has been criticised for poor performance. As a result, a large proportion of buildings have been re-thatched using imported water reed. However, the use of this material can diminish the significance of a building traditionally thatched in straw by altering its appearance. The aim of the project is to develop husbandry regimes to produce more resilient and durable varieties of wheat for straw thatching, and to test their longevity and performance on roofs.
The project consists of two complementary phases. In Phase 1, growth trials of five wheat varieties have been carried out to monitor and evaluate the growing, husbandry and harvesting of the cereal crops, including the use of different fertilisers. In Phase 2 the longevity of straw thatch is being assessed on test panels and a number of re-thatched roofs.
Participants: East Anglian Master Thatchers Association; John Innes Centre; National Thatching Straw Growers Association.
Programme and progress: Phase 1 complete - Report published. Phase 2 in progress.
Contact for all above projects: Conservation@HistoricEngland.org.uk