Stone Slate Roofing
Slate and stone roofs are a significant feature of many historic buildings. To repair and conserve them successfully necessitates the use of appropriate traditional materials and techniques.
A stone slate roof, providing it is well maintained, can last for at least a century and possibly much longer. This section of the website gives details on production, traditional techniques, conservation and sources of further information.
Stone Slate Roofing Technical Advice Note
The Stone Slate Roofing Technical Advice Note provides guidance for specifiers, conservators, contractors and building owners on the repair or reroofing with traditional stone slates in England. It deals specifically with slates produced from limestone and sandstone, rather than from real (or metamorphic) slate.
The guidance provides an overview of current practice and includes:
- Stone as a roofing material
- Principles of stone slate roofing
- Planning and legislation
- Investigation and recording
- Repair and re-roofing
- Life cycle costs
- Checklists for recording historic materials and construction details
Horsham stone roofing
Horsham stone is a group of sandstone beds in the Wealden clay of West Sussex in south-east England. Difficulties in obtaining stone slates for roof repairs resulted in a change of detailing to make the slates go further. The traditional double-lap was changed to a single-lap system and this resulted in confusion between the two systems.
The Horsham stone roofing guide describes the current state of knowledge and offers guidance in conserving, specifying and constructing these important and often complex roofs.
Collyweston Stone Roofing
Collyweston slates were traditionally used for roofs in buildings in north Northamptonshire and nearby counties. Production involved exposing the stone to winter frosts so that it could be ‘clived’ by hand into slates. Production peaked in the late 1800s. In the 1970s cheaper but arguably less sympathetic materials became available and production stopped. Now after many efforts production is making a comeback.
In the late 1990s, English Heritage (now Historic England) teamed up with the Burghley Estate in Lincolnshire and Sheffield Hallam University. They developed an artificial system to reproduce the frosting necessary for production of the slates.
In 2012 Apethorpe Palace needed new slates for parts of its roof. At this point we commissioned further tests to refine the artificial frosting method. The slates were produced and the method has since been used successfully on other buildings. So this distinctive local material is once again becoming more popular.
For more information please visit The Stone Roofing Association & Historic England Collyweston Project page.
Other relevant publications
Traditional roofing has a vocabulary of unfamiliar technical terms for materials and techniques. You can download 'The Glossary of Stone Slate Roofing' from the Stone Roofing Association's website. This short publication explains the terms used in slate and stone roofing and illustrates many of them.
The English Stone Forum have published the papers from a conference held on England's stone built heritage. The papers cover the historic use of stone, conservation practice, supply of stone, and planning issues associated with the use of indigenous stone. A copy of the publication can be obtained via the English Stone Forum website.