Cusgarne House

Cusgarne House is a farmhouse, likely dating from the 17th century, with significant alterations and extensions around the middle of the 18th century. The construction comprises killas and granite rubble, with granite quoins and jambstones. The roof is hipped, covered in dry Delabole slate to the front, featuring alternate crested clay ridge tiles and a wooden eaves cornice with bobbin detail. The rear has scantle slate and some dry slate. Brick chimneys are visible on the side walls and gable ends of the rear wings.

The original plan was for two rooms, with a central stair located in a rear turret flanked by projecting service wings, each containing one room. Remains of a large lateral chimney breast from the earlier period survive to the rear of the right (east) room, and a similar chimney breast exists to the west of the left room. The south front is nearly symmetrical with three windows. The windows are original 18th-century paired sashes, retaining their wide original glazing bars with internal ovolo moulding. The word 'Cosgarne' is scratched into one pane of glass in the ground floor left window. The sashes generally have 12 panes, except for the wider window above the nearly central doorway, which features 16 panes. The original six-panel front door has two later-glazed upper panels, with original flanking sidelights each containing 8 panes. A wide hood with a moulded cornice, supported on brackets and flanked by consoles, covers the doorway.

Some arch and jambstones, likely from an earlier front, are incorporated into the yard wall to the rear (north) of the kitchen. The interior has remained largely unaltered since the middle of the 18th century. The entrance hall and front rooms feature dado panelling. The right (east) room originally had horizontal boarding, but it is now divided into rectangular panels. Elsewhere, panelling is fielded or with ovolo moulding, with some smaller panels, potentially from the earlier period of the house, reused in the entrance hall above the dado and in large walk-in cupboards. An arch connects the vestibule to the stair. Original features include moulded chair rails, doors with fittings, architraves, and window shutters. The dog-leg stair has a moulded handrail, newel caps, and splat balusters. The rear east kitchen has a slate-flagged floor and bowtell moulded beams.

The first floor and roof were not inspected but are believed to be original. Cusgarne House was rented by James Watt between 1781 and 1800, during which time he oversaw the installation of steam engines designed by him, used in Cornish mines. The house presents an unusually intact 18th-century interior and rare survival of complete 18th-century window fenestration with much original glass. The rear elevation is also unspoiled and overlooks a courtyard of unaltered early 19th-century stone outbuildings.