Barn and Cart-Shed range at Castell-du

The building is a barn and cart-shed range at Castell-du, constructed from whitewashed rubble stone and topped with a slate roof. It is a long structure with the barn located on the left and a lofted cart-shed on the right. The barn features a window with a timber lintel on the left, followed by a broad ledged door with stone voussoirs and a cambered head, and then a vent loop. The cart-shed section to the right includes two cart entries with cambered arches, stone voussoirs, and keystones. Above these entries, there is a 2-light loft window positioned between them. On the eastern end, there are outside stairs leading to a ledged loft door, which also has stone voussoirs. The southwest end of the building has a window with stone voussoirs. There is a structural crack on the northwest side. The rear of the building features a tall cart entry to the barn, which is partly blocked, along with a window to the right and a lean-to on the left.

Inside, the barn section has a loft on the left, which was previously on both sides. The roof is supported by seven pegged collar trusses and double purlins.