Cwm Dyli Power Station

Cwm Dyli Power Station is a large rectangular hydro-electric turbine house built in a striking alpine arts-and-crafts style, fitting for its mountainous location. It features quarry-dressed limestone construction on a slightly-battered base, with brown brick and finely finished limestone dressings. The building has renewed slate roofs with tiled ridges and overhanging eaves, along with plain bargeboards and deep verges.

The structure consists of one tall storey topped by a large pitched roof that is hipped at both narrow ends, flanking a prominent central gable. This central gable houses tall round-arched windows, with the upper sections extending above the eaves. The long sides of the building are divided into seven bays, each adorned with broad lacing courses of brick and rusticated brick quoins at the corners. The side windows are smaller versions of those found at the ends, all featuring brick voussoirs, projecting brick sills, and keys. Limestone mullions and transoms create a Diocletian effect, with small-pane glazing that is obscured.

On the east side, there is a two-bay central projection topped with paired hipped roofs, each containing actual Diocletian windows, and four blind brick segmental niches above. There is also a low primary infill section on the south side, with a hipped roof and paired arched windows. A similar arrangement once existed on the north side, but it has been replaced by a more recent flush continuation of the projection that carefully mimics the original style and reuses original dressings.

The entrance front on the north side features a wide segmental arch beneath a large window, which includes a central entrance flanked by lights and boarded doors. The modern alteration on the east side is flush with this facade and includes an arched window with an oculus above it. The interior was not accessible during the survey.