Old longhouse at Nantyfedw

The Old longhouse at Nantyfedw is a one-and-a-half-storey building constructed from rubble stone, featuring a steeply pitched roof made of corrugated asbestos cement sheets supported by original trusses. A square stone ridge stack is present. The layout is distinctive, with the house located at the downhill end and the byre at the uphill end. On the south side, the main doorway to the byre is offset to the right of the stack's position and has a modern head. Further to the right, there is an inserted window below the eaves with brick jambs. To the left of the main doorway, there is an inserted doorway with a cement lintel, a hall window further left with a drip stone, and a doorway to the original parlour, which has been converted from an earlier window and also features a drip stone.

Attached to the lower gable end is a lean-to pig sty with a walled pen in front, added by the Dunraven Estate in the 19th century. Above this, there are ventilation strips below the apex and an upper left narrow window. The uphill gable end has an inserted window under a drip stone, while the rear features an original small stairlight under a drip stone. To the left, the byre has an original doorway and a window to its right set in a brick surround.

Inside, the main door opens into the cow house, which has stalls that were inserted in the 1930s. The stubs of former loft floor beams can be seen in the walls. The roof consists of four bays with curved-foot principals. A round-headed doorway leads from the cow house to the hall next to the fireplace, which has a chamfered timber bressumer. To the left of the fireplace is a round-headed doorway leading to a stone winding stair. The hall features closely spaced cross beams, two of which have stepped stops and are cut to support joists, suggesting they were re-used from another site. A stone partition separates the hall from the parlour, though its date is uncertain and it may have been added after the house was converted for storage. The roof over the house has three bays with curved-foot principals and added collars.