Capel Adfa with forecourt railings

Capel Adfa is a substantial chapel complex comprising three interconnected parts: a galleried chapel, a three-storey caretaker's house with cellar to the west, and a school room with stables to the east. All components are constructed of rubble masonry, rendered and whitewashed on the south and east elevations, with slate hanging on the west side. The roofs are slate with two rendered brick chimney stacks, one at the west end and one to the west of the school room.

The chapel itself follows a traditional lateral entry plan. Its front elevation, facing south, is symmetrical with all openings set under round heads. Two panelled and moulded doors with overlight windows containing Y-shaped glazing bars sit at each end. Between them stand two tall windows with wooden Y-shaped glazing bars under the arched head and twelve panes below, with two shorter similar windows placed near the doors below the roof line to light the gallery. The rear elevation has six small-paned cast iron windows under round arched heads: three lighting the gallery and three the lower level. Two small lean-to structures project from the west side.

The school room and stable block form a lean-to attached to the east end, almost certainly built contemporaneously with the chapel. It features a half-hipped roof with cusped barge boards and a central gablet. The east facade was originally timber-framed. The school room is accessed from the south via masonry steps bounded by iron railings, through a plain planked door under a round arch with overlight. The east facade contains two modern casement windows at first floor level and a small cast iron four-pane window on the north side under a round arch with voussoirs. Below lie two stables accessed from the east via modern doors at the north side of each, with small lights to the south of each entrance. A brick pier abuts the southeast corner of the stables for structural support.

The caretaker's house at the west end has a plain planked door on the south side under a round arch with overlight, and three modern casement windows, likely inserted in earlier openings, one to each storey. The rear elevation projects slightly from the chapel and contains a rear planked door with two four-pane cast iron windows, one at ground floor and one at first floor level.

Interior features include a galleried arrangement with pulpit and sêt fawr positioned on the south lateral side. The gallery is carried on six narrow cast iron columns supporting a moulded plaster cornice above a panelled and decorated wooden frontage, accessed by two staircases in the rear corners. Three rows of pews occupy the gallery, while the lower level contains six rows of pews with moulded chamfered bench ends, with further pews set at right angles towards the front. The pulpit is ornately carved in late 19th-century style featuring recessed lancet-shaped panels and decorated newel post heads. Ornate plaster ceiling roses and coving, together with wood panelling to the lower wall levels, complete the interior decoration. The roof structure is a concealed king-post design constructed from round posts.

The school room retains wood panelling to its lower levels. The south stable is particularly well preserved, retaining three stalls, tethering rings, manger, hay rack, cobbled floor with drainage gully. The caretaker's house comprises a living room, kitchen, and wash house to the rear, with a large attic room at the top that was apparently used for Sunday School tea parties.

A narrow forecourt bounded by iron railings on a stone plinth fronts the chapel.