Top Lodge to St Donats Castle, including attached garden wall

Top Lodge to St Donats Castle, including an attached garden wall, is a building with coursed, squared, semi-ashlar limestone walls and a prominent chimney breast with a stack on the south gable. The stone tile roof features a stack located north of the center and coping on the gable ends. The lodge is one storey with an attic.

On the east (street) elevation, starting from the south (left) end, there is a single light window on the ground floor, followed by a small 2-light window under the eaves on the first floor. Next, there is an arch-headed 3-light ground floor window with sunk spandrels and a dripstone, which is positioned above a similarly headed 2-light attic window in a small gable. There is also a pointed chamfered doorway with a door that has coverstrips, though this is now obscured by a late 20th-century gabled porch with glazed sides and a tiled roof. Additionally, there is a single light ground floor window with an arched head.

To the north gable, there is a single storey stone extension that includes a ventilator and a door with coverstrips in its front wall. The south gable features a small first floor single light lancet window to the left of the chimney breast and a 2-light window to the right. There is also a small trefoil window on the ground floor, and the chimney breast is inscribed with the initial 'W' and the date '1905'. The west elevation is similar, but not identical, to the east elevation, and includes a pointed doorway with a porch in front of it, with the gable positioned against the stack on this side.

The stone front garden wall returns to the house near the south end of the front elevation. Inside, the lodge is said to have early 20th-century ceiling beams in the Arts-and-Crafts vernacular style and an inglenook fireplace.