Earth House (Building 5) At Former Marsh Gunpowder Works, Workshop Area

This earth house, building number 5 within the former Marish gunpowder works’ workshop area, served as a saltpetre refinery and dates from 1800 to 1810. Constructed of yellow brick, it has a corrugated hipped roof.

The building has a rectangular, single-cell plan, bisected by a central dividing wall.

Originally, the exterior featured nine openings on each side, finished with rubbed brick flat heads. Most of these openings have since been blocked or altered on the southwest side. The northeast side retains several original eight-pane hornless sash windows, two flanking a doorway at the east end, two more closely spaced on the other side of a near-central doorway, and two taller windows at the east end flanking another doorway. A more recent vehicle entrance has been inserted into the northwest end.

Inside, the roof is supported by five king post trusses with pairs of ties to the end walls and diagonal struts, corner ties, and is lined with matchboard.

The Marish works were part of the Royal Gunpowder Factory established outside Faversham in 1786, following an explosion in the town, and played a pivotal role in improving British gunpowder production, particularly during the Napoleonic Wars, under the direction of William Congreve. The saltpetre refinery was built in 1789 as part of Congreve's efforts to improve gunpowder ingredients. The works were privatised after the war and closed in the 1920s.

The earth house originally stored unrefined saltpetre imported from the East Indies prior to processing within the refinery complex. It is the earliest and only surviving example of six such structures built here in the early 19th century. The relatively elaborate window arrangement suggests it may have been intended for, or quickly adapted to, alternative uses. This building forms part of a distinct and well-preserved group of late 18th to early 19th century industrial buildings used for refining saltpetre, which is the best preserved of its type nationally and comparable with examples in France and Sweden.