Foundry at Felin Fawr Slate Works

Tall rectangular plan building, aligned roughly north-south. Coursed and dressed slate slab construction with granite quoins and gable-ended slate roof with stone kneelers; circular brace plates. Four 3-light timber windows with long slate lintels and cills on western side. South gable end formerly with external, tapering square stack in orange brickwork, the remaining brickwork of which rises above the brickwork of a round-arched opening; infilled doorway to right. Similar arch to north gable end which also has a small lean-to roofed section in north-west angle. Eastern roof slope with rooflights, wall below concealed by adjoining fitting and repair shop. Lower gabled, slated range with small brick stack runs at right-angles to west at southern end, against which is an open 3-bay slate-roofed lean-to on cast-iron columns, the eastern bay of which overlaps the southern gable end of the main building.

Interior retains massive wooden trusses with braced timbers on cast-iron brackets formerly supporting a travelling crane.