Valve House, Loch Sloy Hydro-Electric Power Station, Inveruglas

Loch Sloy Hydro-Electric Power Station was designed in 1947 by Harold Ogle Tarbolton, working for the North of Scotland Hydro Electric Board, and built in 1950. It is a two-storey, five-bay, rectangular classical modern power station with a lower office block attached to its southwest side. The building's southeast elevation, the principal facade, is dominated by a full-height, eleven-bay arrangement, with a tall, six-bay turbine hall to the northeast and a lower range of offices and stores to the southwest. Prominent, full-height pre-cast pilasters are a defining feature of the southeast turbine hall elevation. The building has a steel frame with pre-cast Rubislaw and Corrennie granite slabs, and features a banded corniced eaves course and a deep blocking course above.

The southeast (principal) elevation includes a slightly advanced four-bay centre to the turbine hall, flanked by single outer bays (the one to the northeast being blank), and features giant order pilasters with dentilled capitals dividing the bays. These pilasters oversail the tailrace, which sits on concrete piers and is defined by segmental arches. Large, full-height rectangular windows are set into moulded concrete surrounds on the ground floor, with a banded cill course beneath them. Smaller windows are positioned above in narrow moulded surrounds. The lower section to the southwest has four full-height windows with cantilevered concrete balconies and doorways above, similar to the single bay return. A slightly taller, recessed single bay is located at the far left, with matching windows.

The southwest (entrance) elevation features a three-bay advanced entrance block flanked by single recessed bays. The advanced doorpiece is flanked by rectangular windows at ground level, with a balcony above incorporating the North of Scotland Hydro Electric Board coat of arms. A tall rectangular window is located at the first floor, framed by a moulded architraved surround. The office block shares similar windows and balconies with the southeast elevation.

The northwest (rear) elevation is similar to the southeast, with a panelled teak vehicular access door in a plain surround, a transformer station adjacent to the rear of the turbine hall elevation, and a roughly four-bay advanced workshop to the southwest. A symmetrical arrangement of two bays defines the northeast elevation, each featuring full-height windows at ground level and smaller rectangular windows above.

The windows are predominantly small-paned, with some hopper top openings in painted Crittal frames. A flat platform roof sits behind a parapet, and decorative cast-iron rainwater goods are present with decorative hoppers.

Inside, a full-height entrance vestibule includes a dog leg stair on axis with the door. This stair provides access to a balcony on the first floor. The entrance features octagonal section pillars with polished marble and marble tiled walls. Various offices and store rooms are also present, with a main control room directly opposite the entrance door on the first floor, retaining original control panels dating to 2009. High-quality fixtures, including stair handrails and some oak doors with brass handles, are notable. The turbine hall’s interior is predominantly plain and functional, featuring a large travelling crane across the gantry at attic level and a trussed steel roof structure.