Cefn-y-Waen Chapel including Vestry/Schoolroom and forecourt walls

This is a Romanesque style chapel, built in the 18th century. The chapel is constructed from rock-faced stone with snecked detailing, featuring buff ashlar dressings and a slate roof. The front of the chapel has three bays, with giant pilasters that extend to a pedimented gable featuring a stepped Lombardic cornice and an oculus. A large wheel window with ten lights is centrally positioned, with paired round-headed doorways below, adorned with floral capitals to the jambs and boarded doors with overlights. The outer bays are characterised by two-light round-headed windows above the oculi, each framed by a semi-circular top. The side elevations are two-storey with six bays, exhibiting round-headed windows (the upper floor windows being taller) and mainly modern glazing. The rear gable mirrors the front with a Lombardic cornice and an oculus. Rubble forecourt walls incorporate wrought-iron railings, gates, and gatepiers to the right of the chapel front.

A rear vestry/schoolroom is set at a right angle to the chapel, built with rendered walls and a slate roof. It features a gabled porch with modern doors on the right side, a round-headed window to the front, and windows to each side.

The chapel's interior features an outer vestibule with flanking stairs leading to a gallery, connected to an inner vestibule. The main body of the chapel has two aisles. The ceiling is finely detailed with a classical cornice, an outer margin strip with sunk panels, and elongated oval panels flanked by square and octagonal panels with moulded roses. The boarded central section includes a ribbed and boarded octagonal panel containing an octagonal rose, with pierced ceiling vents at the ends. The walls are plaster-scribed to resemble ashlar, with a matchboard dado. The gallery extends around three sides, supported by iron columns with Corinthian capitals. The wooden gallery front has broad panels, and the chapel contains box pews. The central block of box pews is divided from those underneath the galleries by the aisles; pews near the set fawr face inwards. The set fawr enclosure is panelled with a shallow strip of baluster arcading above it, and includes built-in bench seating. A panelled pulpit, topped with a heavy cornice, is flanked by curving stairs. Behind the pulpit, a semi-circular arch encloses paneling with a hymn board.

The vestry/schoolroom has a ceiling with circular vents, scribed rendered walls, and a matchboard dado. A dais is present with a lectern and a balustraded parapet with square newels. Side windows and one to the rear retain sash glazing with marginal bars.