Treverbyn Mill

Treverbyn Mill is a watermill, likely dating from the 18th century, with some 19th-century additions. The mill is constructed of slatestone and granite rubble with granite quoins, and has a hipped slate roof. The plan comprises a three-story mill with a launder running along the right side, the water entering from the rear and driving an overshot wheel. A single-room addition to the rear, probably for storage, was added in the 19th century.

The front elevation has a stable door to the left and a small door with strap hinges to the right. A stable door is located at first-floor level to the right, and a dormer with a hipped roof contains a two-light casement with toplights. The left side has a two-light casement at ground floor and two similar casements at first floor. The rear addition features a door with chamfered granite jambs and lintel, a four-pane light above, and a two-light casement at first floor; it is covered by a corrugated iron roof with a gable end. The right side has a two-light opening with shutters in the mill and a door to the addition. A wooden launder includes an adjustable wooden board allowing the water flow to be disconnected from the wheel. The waterwheel is cast iron with cast iron floats. The rear elevation includes an eight-pane three-light casement at ground floor with L hinges and a cambered brick head, and at first floor a two-light eight-pane casement with a granite lintel.

Inside, there is no pit wheel; the waterwheel drives the great spur wheel directly at first floor level, with an ancillary drive to the stones formerly located at second floor level. The stones have been removed. The mill is currently used for grinding cattle feed, with a hopper running from the second floor to the first floor, where the ground grain is sent into a feed mixer. A hatch provides access between the ground and first floors. A further ancillary drive on the first floor connects to a belt drive for other machinery. The roof is of the 19th century, with principal rafters crossed at the apex and bolted, and purlins resting on the backs of the principal rafters.