Ystumllyn

Ystumllyn is a large, two-storey house, originally built aligned northeast-southwest, dating from the 17th century and significantly remodelled in the 18th century. The house is constructed of rough slate rubble with a modern slate roof and overhanging eaves. There are rear wall and right-hand gable stacks. The main range faces southeast, featuring a low, narrow central entrance within a roughly semi-circular archway constructed of cyclopean stonework, which aligns with a later entrance in the rear wall (now the primary access point). The first floor has four irregularly spaced 16-pane sash windows; one window on each floor is a 20th-century insertion. A narrow 12-pane sash window is located alongside the doorway, paired with 16-pane sash windows to its right (previously a tripartite sash window). Further 16-pane sash windows are present on both floors alongside a stack on the rear wall of the main range, and in the gable end. A wing extending to the northwest houses a stairhall and a principal room, with two 16-pane sash windows on each floor along its southwest elevation; a doorway is centrally positioned, with single sash windows above the staircase. A projecting stack is on the northeast elevation of the wing, alongside a cellar entrance, and a doorway with a panelled door within a moulded architrave inserted around 1946, with a 16-pane sash window above.

Lower extensions to the northeast of the main range lead to a higher gabled cross range, likely formerly a stable and loft, with a central door and flanking windows on its northeast elevation, and an external staircase leading to a loft doorway in its northwest gable. A single-storey wash house encloses the courtyard to the northwest, with a door and a single 6-pane sash window on its southeast elevation, along with a tall stack on the gable end.

Initially, the house comprised two rooms with a central service room or wide internal passage between them. The northeast room (now the kitchen) features stop-chamfered spine beams with run-out stops. The southwest room has heavy beams paneling the ceiling, with all beams and joists exhibiting run-out chamfer stops. A rear wall fireplace incorporates coats of arms (Collwyn ap Tangno and Owain Gwynedd) within a panelled surround; the lower panels (German Renaissance reliefs) and the Delft tiled surround were inserted around 1946. The staircase in the rear wing likely dates from the 1729 extension and remodelling, but has likely been realigned since, and features turned balusters, moulded strings and rail, square newel posts, and a fielded panelled dado. A massive queen strut and collar roof truss is found in the southwest section of the main range, where the present roofline is not aligned with it. The three trusses in the wing are of a later Queen Post and collar type, and the two trusses in the northeast part of the main range are similar.