Melting House (Building 20) at Former Marsh Gunpowder Works, Workshop Area

The Melting House, also known as Building 20, is a single-storey structure located at the former Marsh Gunpowder Works in Faversham. It dates from between 1800 and 1810 and was originally part of a saltpetre refinery. The building is constructed from red brick and features a hipped roof made of corrugated iron.

The plan of the building is rectangular with a single cell. The exterior includes a wide full-height opening on the southeast side, accompanied by a louvered light to the right. The rear side has two cast-iron windows, and there are two buttresses at the northeast end.

Inside, the Melting House has two king post trusses that are connected to the end walls with ties and diagonal struts, along with corner ties.

Historically, the Marsh works were part of the Royal Gunpowder Factory established in 1786 following an explosion in Faversham, aimed at relocating more dangerous processes. The works played a significant role in enhancing British gunpowder production 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 the quality of gunpowder ingredients. After the war, the facility was privatized and ultimately closed in the 1920s.

The Melting House was specifically used for boiling saltpetre in solution before it was transferred to the adjoining refining and crystallizing house. It is part of a well-preserved group of late 18th to early 19th-century industrial buildings for refining saltpetre, recognized as the best preserved of its kind in the country, and comparable to similar structures in France and Sweden.