Melin Adda is a converted three-storey tower mill with single-storey extensions on its south side. In 1975, when the shell was being converted, it was possible to see the mill tower's rubblestone construction and small, square windows. The tower was 8.8 metres tall, and once had floors at 2.8, 5.85 and 7.9 metres; the internal diameter at ground level was 5.5 metres. The now-rendered tower is capped by a pitched slate roof incorporating a cross gable with brick chimney, a balustraded viewing platform at the rear, and a replica horizontal windshaft with a modern iron cross and four timbers representing the sails.
The mill probably worked in association with the adjacent water mill (NPRN 24618).
W J Crompton, RCAHMW, 18 June 2006.