Part of the Maenofferen Slate Mine (NPRN 400427), a single storey building orientated E-W and measuring 24.5m x 12m; constructed of coursed slate blocks on a slate slab foundation with a pitched slate roof. The building was constructed as the Workshop Range for the Upper Maenofferen complex after 1939 according to the plans held by J. W. Greaves and Sons Ltd and was decommissioned in 1999, with the majority of machinery left in-situ. It is subdivided by partition walling into three separate units of similar size, used as a Smithy (NPRN 415929), Saw Mill (NPRN 415931) and Engineering Workshop (NPRN 415933). There are two further annexes, a coal store, 2.6m x 4.6m attached to the NE corner of the range and a store 3.9m x 4.7m attached to the SW corner.

References: Plans referred to are held by J. W. Greaves and Sons Ltd, Blaenau Ffestiniog

Louise Barker & Spencer Gavin Smith, RCAHMW, August 2011