Nant y Bai Mill

Nant y Bai Mill is a mill and mill-house built as a long, single range, likely dating to the 18th century, with the two-storey, two-unit mill-house situated on the right and a longer mill building to the left. The structure is constructed of limewashed rubble with slate roofs. The mill features a wide, segmentally arched central doorway, flanked by four-pane fixed light windows. A secondary door is located to the right, and a small opening provides access to the machinery bay on the lower left. Two four-pane windows are visible in the upper floor. An overshot or high breastshot water wheel, measuring 16 feet (4.88 meters) in diameter and featuring a cast-iron rim marked “T. Bright, Carmarthen,” is located against the end gable. The rear wall is built of river boulder rubble, with the lower courses indicating earlier construction. Various small openings are present, including a possible former axle hole for an earlier wheel and an obliquely angled opening of uncertain original purpose.

The mill-house presents a two-storey, three-window range, offset to the left, with eight-pane sash windows. A 20th-century glazed door with overlight is also present. Yellow brick surrounds the ground-floor openings, while timber lintels are above the upper windows. End stacks are visible; the stack on the left is brick and shared with the mill building, serving a corn-drying kiln within the mill.

Internally, the mill is divided by four chamfered beams, with the left-hand bay partitioned and housing machinery that appears to be largely complete, including an iron pit wheel, spur wheel, and associated gearing, all on a cobbled floor. A large brick kiln occupies the right-hand corner, featuring a cast-iron lintel over the fire box and perforated tiles visible in the upper storey. Three sets of wheels are situated at first-floor level, along with remnants of various chutes from the attic. The roof trusses, likely reused during a 19th-century reconstruction, are A-frame trusses, halved and pinned at the apex with a saddle; they were cut for collar beams, which are now absent. The mill-house retains its original layout and some original features, including a large principal fireplace.