Penallta Colliery Engine Hall and Fan House

The Penallta Colliery Engine Hall and Fan House, dating to 1906, is a substantial building that forms a key part of the colliery complex. The building is oriented east to west, standing at a right angle to other structures on the site, and measures approximately 100 metres long and 23 metres wide. A fan house is attached to the eastern end. The roof is gabled and now has a corrugated metal covering over original steel trusses; the parapetted gables retain the original profile, combining a raised ventilator and roof light at the top with a sloped section featuring slate and glazed panels. The building is constructed primarily of Pennant sandstone, with some rendering, and has red brick dressings, including pilasters dividing the bays, end piers, stepped parapets, a plinth, dentilled window and door surrounds, and keystones. The main facade is 16 bays, with tall segmental arched windows featuring deep angled jambs at ground level, and a row of smaller windows above. Some original metal-framed small-pane glazing remains, although the ground-floor windows on the south side are now blocked. A central double doorway is flanked by a tablet inscribed 'P.D. 1906', with a taller doorway to the right. The western gable end has rendered panels between pilasters, two rows of windows and one doorway, all constructed in red brick. To the east, a lower extension houses the fans and fan engines, with windows in the gable above and a sloping brick tunnel leading to a tall evase for air expulsion. An attached retaining wall extends from the base of the building.

The interior is notable for its continuous arcading on all four sides, featuring carved pilasters with carefully detailed Doric capitals and arch rings highlighted in green and cream. A tiled dado incorporating numerous coloured floral designs is also present. The building retains runners for a travelling crane, and the original lattice-girder crane remains in situ. The original steam engines were replaced in 1962-3 with electrically powered equipment; the building now accommodates two winding engines, a compressor, three generators, and switchgear. Patches of original black and cream tiled flooring and cast iron railings survive. Openings in the floor provide access to a basement level used for engine servicing, accessible via doors on the north side. This building is given group value in that it demonstrates a significant example of industrial architecture.