Melin Llecheiddior is a two-storey corn mill with two overshot waterwheels in tandem. There is no pond, but an 1100m-long leat carries water from a weir across the Afon Dwyfach directly to the mill, where each wheel is fed by individual sluices in the floor of the wooden launder. Each wheel drives a single pair of stones directly through a pit wheel and stone nut/wallower; as the stones are never out of gear, sluice controls are used to start, stop and regulate the speeds. The first or more northerly wheel is of timber construction whilst the second wheel to the southeast has cast iron hubs and shrouds. A third, undershot, waterwheel, southeast of the second, was later installed in the tailrace from the main waterwheels to drive a butter churn; it consists of a single cast-iron wheel, about 1.5m in diameter, and originally had wooden paddles fixed around the rim.
A corn drying kiln is attached to the mill on the southwest and beyond is a small store; adjoining to the southeast of the mill is the millhouse, the whole complex forming an L-plan range with all buildings of local stone under pitched slate roofs.
Brian Malaws, RCAHMW, 13 March 2010.