Tan-y-garth bach

Tan-y-garth bach is a single-storey building with a two-room plan, oriented roughly north-south, and featuring lofts above both rooms. The exterior is made of roughly coursed rubblestone that is rendered on the south gable, topped with a slate roof. The front of the building has four-pane sash windows with slate cills on either side of an offset boarded door, which is sheltered by a flat-roofed slate porch. To the right, there is a substantial integral end stack, while a smaller internal end stack with a brick shaft is located on the left. A small 19th-century skylight is positioned to the right, and a larger 20th-century rooflight is on the left.

On the right gable end, there is a single-storey lean-to, and a continuous catslide outshut at the rear features an unbroken wall with an eaves height just above track level. The larger room on the right has an infilled fireplace and comparatively heavy exposed joists in the ceiling. The smaller room on the left, accessed behind the staircase, has narrower joists aligned with the main axis and a small 19th-century cast-iron fireplace. A narrow straight-flight staircase, directly in line with the entrance, leads to the loft, which is larger and stepped up over the right room (the original croglofft) and smaller over the left room, with exposed single purlins.