Penddaulwyn Fawr, including attached farm building

Penddaulwyn Fawr is a two-storey, two-window house built of whitened rubble stone with a slate roof and brick stacks, one of which has been rebuilt. The openings feature brick segmental heads. The central entrance includes a boarded door set in a half-glazed lean-to porch. The wooden cross windows beneath cambered heads have casements. An additional lean-to structure is attached to the left gable end. At the rear, there is an outshut that contains a dairy on the right side, with mid-20th century windows on the left side.

Adjacent to the right (downhill) gable end is an earlier lofted farm range, constructed of limewashed rubble with a slate roof. Its openings have wooden lintels. At the left end, next to the house, is a cross-passage doorway. To the right of this doorway, stone and brick steps lead to a loft doorway beneath the eaves. Further to the right are three cow-shed doorways with split boarded doors and two shuttered loft openings beneath the eaves. The downhill gable end features a loft doorway, above which are ledges and pigeon holes framed in brick. The rear lean-to has an asbestos-cement roof.

Inside the house, the entrance hall has a slate floor that leads to a close-string staircase. The right-hand room contains a fireplace with its lintel removed, flanked by cupboard recesses. The dairy features slate troughs.

In the cow house, the six-bay collar-beam roof, which has iron bolts, is a 19th-century replacement of the original roof, possibly installed when the pigeon holes were added. The structure retains stalls for horses, indicating that it was later used as stables.