The old engine shed was constructed, according to plans held by J. W. Greaves Ltd between 1902-1939 as the original engine shed for the Maenofferen Slate Quarry locomotive stock and is situated adjacent to the tip run to the north of the River Bowydd (NPRN ****). The building was derelict by 1975 and is now missing its roof and internal fittings.

It comprises a single storey building orientated NW-SE and measuring 8m x 4.4m externally, with a double door in the NW gable end and single light windows in the SE gable end and SW wall. It is constructed of coursed slate blocks and the walls are 0.5m thick. A foundation plinth is evident along the south side of the building where the ground level is at a lower level. There is also a 3.8m length of wall which runs NW from the SW corner of the building.

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

Louise Barker & Spencer Gavin Smith, RCAHMW, August 2011.