CONTEXT 185 : SEPTEMBER 2025 17 ROOFING CHRIS WOOD A code of practice for slate and stone roofing Historic England intends later this year to consult on a code of practice for repairing historic stone and slate roofs, and on the technical advice note that will support it. Slate and stone roofs are often the most important part of a historic building. They may contain evidence of structures and detailing going back many centuries and are usually the least altered parts of a building. But much of the subtle detailing which gives them their attractive and unique character is being lost during works which comply with modern standards and recommendations. As a result, Historic England is intending to publish a Code of Practice for Slate and Stone Roofing which aims to provide best practice advice and guidance for repairing historic stone and slate roofs. The code will be supported by a more detailed technical advice note (TAN). The draft documents are expected to be ready for consultation with heritage bodies and industry by late autumn. The need for a code of practice Current standards and guidance documents are mainly written by the industry and intended for new works, and inevitably champion modern methods and materials. A number of important standards and codes include recommendations that are unnecessary and positively harm the significance of historic and traditional buildings. Many roofers who work on these buildings are not trained in the use of vernacular methods and detailing and have not even used traditional materials. This is not a new problem. A decade ago, the author of this article suggested in the industry’s magazine Roofing Today that a new code providing advice for those working on historic roofs was needed. Vitriolic complaints were expected, but surprisingly the feedback was very positive as many contractors agreed with the idea. The main British Standards are BS 5534 (Slating and tiling for pitched roofs and vertical cladding, Code of Practice 2018) and BS 8000-6 (covering workmanship), which tend to be followed by many specifiers and contractors who use the National Building Specification (NBS) by default. BS5534 contains a great deal of extremely useful advice and guidance, but it Cleft oak laths (seen here) were traditionally used to hang hand-made tiles and stone slates. Much of the attraction of these roofs rests with the slight undulations of each course, which has much to do with the laths. Today, BS5534 stipulates that 50 mm x 25 mm sawn battens are used for safety reasons to take the weight of a roofer, unlike cleft lathes, apparently. (Photo: Chris Wood) Torching with lime mortar on a Devon scantle slate roof is a very effective method of excluding driving rain, powdery snow and pollutants, and buffering condensation, which then evaporates to the outside air. (Photo: Terry Hughes)
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