Water Wheel House between slab mills at Felin Fawr Slate Works

Rectangular plan building, aligned roughly north-south. Reddish brown brick laid in Flemish garden wall bond; gable-ended slate roof, collapsed at northern end, collapsing and with majority of slates missing to southern end at time of Survey. 2 surviving full-height openings with slate lintels to eastern wall; tall rectangular window (joinery gone) with slate cill and lintel in south gable end. Northern gable end collapsed.

Interior retains overshot wheel set low in a brick-lined wheelpit; wheel has cast-iron frame with only the lower wooden paddles intact. Drivegear and related machinery remain along with the ironwork header tank and panelled angle pilasters over the northern part of the wheel-pit.