Agricultural Range known as 'the Barn' at Heol-ddu

The Agricultural Range known as 'the Barn' at Heol-ddu is a tall two-storey building constructed from rubble sandstone masonry, featuring dressed quoins and a slate roof. The front elevation, which faces south-west towards the main farmhouse, has three openings: a central heck door that is 1.22 meters wide, walled-up windows, and three evenly-spaced square loft openings above. The doors are boarded and not original, with timber lintels. There is a similar-sized heck door located centrally at the rear. To the left end, there is a stepped-down low outbuilding, also built of rubble and topped with a slate roof. A ruinous pigsty is situated at the rear. The right elevation includes a central door and a large walled-up opening above, while the left gable elevation is largely covered in ivy.

Inside, the building features a five-bay roof structure supported by light collar-beam trusses. The rear wall has two rows of three ventilator holes, and the left gable has three rows of blocked holes, with two, four, and four holes respectively. There are possible marks indicating a loft or upper floor on the left side. A shaft for belt-pulleys remains at the right, but no other machinery is present.