CONTEXT 185 : SEPTEMBER 2025 21 ROOFING TERRY HUGHES Reslating an ancient water mill The need for major repairs to a historic mill provided a rare opportunity to record, study and repair early vernacular roofs, using authentic materials and traditional techniques. Melin Daron is an ancient water mill in Aberdaron village on the Llŷn peninsula in Gwynedd, north Wales. The buildings were covered in a variety of slate roofs as the mill grew over the centuries, but by 2022 they all needed substantial repairs. This provided a rare opportunity to record, study and repair early vernacular roofs, using authentic materials and traditional techniques. The re-roofing was mostly completed in 2024, with the final two roofs due to be conserved in 2025. The mill is the most complete survival in the region, with the majority of the machinery still in its original position. It is believed to have existed from at least the 13th century, when the village was the embarcation point for pilgrims visiting Bardsey Island. Three pilgrimages to Bardsey, acts of Christian devotion, were the equivalent of one to Jerusalem. An archaeological investigation suggested that the mill was built in three phases. In 2022 a preliminary survey report by Slate and Stone Consultants (S&SC) concluded that the roof had historical significance and should be conserved as found (rather than a notional restoration) to illustrate the evolution of slate quarrying, roof slates and slating techniques from vernacular to modern. This was agreed by the charity Melin Daron Cyf, Cadw and Gwynedd Council’s conservation team. A conservation slating and tiling company, W J Conservation (WJC), led by former SPAB fellow Richard Jordan, was appointed to carry out the work, and a provisional reslating plan was prepared with S&SC.1 This would be revised in detail during stripping. The objectives of the detailed plan were to reinstate the slating, applying the existing vernacular and the more modern slating techniques² ; to reuse as many as possible of the existing slates; and, where necessary, to improve the roof’s resistance to wind and rain to combat climate change without unacceptably affecting its appearance. This would follow the principles of Historic England’s upcoming Code of Practice.³ The oldest part of the remaining slating was on Phase 1, Slope 2 and the valley. It consisted of small, thick, coarsely textured slates peghung on riven laths and torched in 1:1 air lime: sharp sand mortar. Originally all of Phase 1 would have been similarly slated. These slates are typical of the production in small shallow quarries operated by a few workers and with a small output. They were produced in random The mill in 2022 (Photos: Andy Marshall, Architectural Photography) All photos by Terry Hughes, S&SC, unless otherwise credited 1 Architect Donald Insall Associates, Conwy; main contractor Grosvenor Construction ² Vernacular and modern slating techniques are explained and illustrated on the S&SC Historic Roofs website, https://bit. ly/4eorfiI ³ Conservation and Repair of Slate and Stone Slate Roofs (in preparation)
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