Primary House at Plas-yn-Llan

Plas-yn-Llan is a long, one-and-a-half-storey house that features a continuous slate roof. The two upper bays on the western side have lower sections and a gable end made of limestone rubble, with exposed timber framing above. The rest of the building is primarily limestone rubble, showing signs of former timber framing; however, the right-hand third of this section has been rebuilt at the back using modern breeze blocks.

On the north side, there is an entrance on the left with a later 19th-century multi-pane fixed window next to it. To the right, there is a wide, segmentally-arched brick opening, dating from around 1900, which serves as a cart bay. Following this are three more entrances: the first is open, while the others have boarded stable doors. The upper storey features two small 2-light windows under the eaves, made with wooden mullions. To the right, there is a loading bay within a catslide dormer that breaks the eaves line. The left (eastern) gable has a brick chimney from around 1900 with a simple cornice. The timber-framed section on the right includes two additional entrances and an open loading bay at the gable, with exposed timber lintels throughout. At the rear, the timber-framed section is mostly open, except for the right bay where the framing is infilled with early brick. In the centre of the stone section, there is a small, early 17th-century 2-light wooden mullioned window now at ground level, with another window featuring a boarded shutter above it.

Inside, the building has a seven-bay layout with tie-beam and raking strut trusses, likely from the 17th century, along with modern purlins and rafters. The two easternmost bays have beamed ceilings with stopped-chamfered joists, the first bay featuring ogee-stopped details. This area also includes an inwardly-projecting chimney breast with a curved, stopped-chamfered bressummer above its fireplace, which contains a later bread oven. Adjacent to the right is a 19th-century wash boiler. The first two bays are separated by a truss partition on the upper floor, which retains its lime-plastered wattle and daub infill panels, along with a primary central doorway.