Plas Glyn-y-Mel, including quadrant wall & gatepier to W service court

Plas Glyn-y-Mel is a country house, likely dating from the 18th century, constructed of rubble stone and originally roughcast, with a slate hipped roof. Two rendered ridge stacks are located on the front roof, and another on the north-east end. The main south front presents a tall, three-storey facade with three windows, raised on a full basement. The overhanging eaves feature Greek Doric flat mutules. The front is cemented to conceal the red brick window surrounds. A second-floor or attic storey includes paired casements to either side and an unusual, pivot-hinged traceried oval light in the centre. The first floor has plain, early 20th-century four-pane sash windows, with a tripartite sash window of four-twelve-four panes and a small fanlight above, forming a simplified Palladian composition. The ground floor displays larger four-pane sashes to either side of a broad doorway, which is set within a later, columned porch. The porch appears to have been added, as a large fanlight is just visible above its flat roof, replacing a wooden pedimented porch shown in a sketch of 1825. The porch is accessed by a substantial stone double staircase of eleven steps on each side, with wrought iron balustrades. A broad doorway accommodates half-glazed panelled double doors and side lights. Basement windows with four panes are set in shallow niches with semi-elliptical heads, located on either side of the steps.

A quadrant wall extends to a surviving, large, battlemented gatepier built around a rough stone monolith, forming a service court to the west of the house. Behind this is a convex-curved whitewashed rubble outbuilding with a grouted lean-to roof, featuring two two-light shuttered windows and a board door.

The west side of the main house has a two-window range, with four-pane sashes to the left, a nine-pane attic sash in the centre, and a twelve-pane sash on the main floors. A basement door is situated between two windows to the left, and an added hipped projection with a further lean-to is located to the right of the centre. The lean-to contains a door and a sixteen-pane sash.

The east side of the house is rendered and includes a 20th-century conservatory and, on each floor, large, late 19th-century four-pane sashes, as well as nine-pane sashes to the attic.

The interior is distinguished by a square entrance hall, screened by a three-bay Roman Doric colonnade, from an axial passage and a central rear staircase. The hall contains a 19th-century marble fireplace. The basement is accessed via a dog-leg staircase, which was possibly renewed in the 1920s. The main staircase may have originally had a double lower flight, as matching arches with square pilasters are present on either side of the return flight, though only the stair rising to the left remains, featuring a ramped rail with unusually scrolled ends on a slope and scrolled tread ends. The axial passage leads to the principal rooms. To the left, paired doors lead to two west-facing rooms, separated by a pilaster. The front left room showcases a leaf cornice with guilloche moulding, a shallow Adamesque sideboard recess with pilasters, and a 1920s fireplace, with six-panel doors throughout. The rear left room is simpler, with a six-panel door, shutters, and a plain cornice. On the right, double five-panel doors lead to a large room which was likely altered in the early 20th century with an altered fireplace. This room also features a simple cornice.