History

Water-powered slab cutting mill first recorded in 1846, though likely to be of late C18/early C19 origin. It served the Diffwys Casson quarry (the earliest in Blaenau) and was used for the sawing and planing of slate slabs. From 1865-1873 the building was used as a school following the construction of a newer and closer mill at the quarry. In 1881 Jacob Zadrach Jones converted it into a woollen mill which was subsequently run in conjunction with Moelwyn mill in Tanygrisiau, the former as the manufactory and the latter as the finishing mill. Amongst the items produced were tweeds, flannel, stockings, Welsh tapestries, blankets and knitting wool. Extended northwards in the early C20, the mill and its sister mill in Tanygrisiau finally ceased production in 1964.

Exterior

Single-storey rubble building with large waterwheel to S and later 2-storey addition to N; modern slate roofs with continuous skylight to mill section and oversailing eaves. 5 large 30-pane windows to the long W side of the mill (of which 2 are modern replacements). E side partly built against the hill with reduced entrance towards S; chamfered C19 doorcase and boarded door; large slate-stone lintel. 2 further (blocked) entrances to R beyond. Small slate-flagged yard to northern part. Original arched entrance to N gable discernible from within though now hidden externally by the addition. This has a stepped-up first-floor catslide bay with continuous modern glazing. Modern multi-pane windows and plain bargeboards to gable end; this with boarded entrance doors.

External overshot waterwheel (7m diameter) served by the Afon Du and via a raised leat carried on a slightly tapering rubble pier; wheel and leat restored.

Interior

Suspended and boarded C19 pine floor to mill section. 4-bay roof with king-post trusses (c1881). This carries the complete original overhead transmission shafting mechanism with 16 separate wheels, formerly driving the machinery with belts.

Reasons for Listing

A well-preserved and important surviving slab- and subsequently woollen mill retaining its waterwheel and internal shafting.

External Links

• Cadwr Listing
• Wikidata Q29484341

External links are from the relevant listing authority and, where applicable, Wikidata. Wikidata IDs may be related buildings as well as this specific building. If you want to add or update a link, you will need to do so by editing the Wikidata entry.

Recommended Books

• 
  London 1: The City of London: City of London v. 1 (Pevsner Architectural Guides: Buildings of England)
• 
  Devon (Pevsner Buildings of England)
• 
  Maintaining and Repairing Old Houses: A Guide to Conservation, Sustainability and Economy
• 
  Hertfordshire (Pevsner Architectural Guides: Buildings of England)
• 
  Suffolk: East (Pevsner Architectural Guides: Buildings of England)
• 
  Wiltshire (Pevsner Architectural Guides: Buildings of England)