Dyffryn Mymbyr

Dyffryn Mymbyr is a storeyed house constructed of rubble, resting on a part-boulder plinth. It is distinguished by its exceptionally long quoin-stones. The original render has been lost, and the masonry is heavily pointed in cement. The roof is renewed with small slates, featuring rubble gable parapets and a squat 19th-century chimney on the right side, along with plain capping and weather-coursing. The front of the house has two windows and an off-centre entrance on the left. This entrance features an original cyclopean lintel with a Tudor-arched opening. The windows consist of 12-pane sliding sashes in later openings on both floors, with the first-floor windows being smaller and all modern replacements. There is a later catslide extension at the rear, which has been modernised, and further modern sliding sashes. A three-part sliding sash window is located on the ground floor of the left gable.

Inside, there is a very wide fireplace on the right side, which was part of the former hall, featuring a massive flat bressummer. The ceiling is crisply framed with deeply-chamfered cross-beams and stopped-chamfered joists, although a few joists on the left side have been replaced. Evidence of mortising indicates a former post-and-panel screen to the left of the entrance, which survives in part and has been relocated to the first floor. There is no visible evidence of an opposing entry that would have formed a cross-passage, likely destroyed when the rear extension was added. A modern staircase leads to the first floor, which has modern partitioning, although the trusses are visible. The roof structure is three-bay with original pegged collars and queen struts. There is a post-and-panel partition in the right bay, which has been relocated from the ground floor, with an ogee-headed doorway in the centre.