The cast house and foundry adjoins the southern elevation of the blast furnace and is where the molten iron was tapped into pig-iron moulds before being reworked and cast by the foundry that occupied the same building. It is believed to have been constructed as part of the earliest phase of construction around 1795 ? 1798 by John Wilkinson, being contemporary with both the patternmaker's workshop and the blast furnace. The cast house and foundry remained in use until the sites closure in 1990, with a number of alterations made to the structure between its construction and disuse. The building is largely constructed of stone, with a number of later stone and brick infill's and alterations. The north wall is made of the blast furnace and blast wall, with the charging wall being supported by a large buttress. An arch of the blast furnace is where molten iron was tapped into the cast house. To the southern end of the west wall two cupola furnaces have been inserted, with brick arches to support the stone wall above. Both the north ends of the east and west elevations once had stone arches, which have since been blocked up. The south end of the building abuts the patternmaker's workshop. Internally the structure been changed to incorporate modern machinery, such as cranes and electric grinders, but the cast floor remains largely open, with evidence remaining of moulds and green sand, which was used for mould castings. Alterations to the structure include the raising of the original roof to create windows and replacement with corrugated iron, infill of the original long-wall arches, insertion of two cupola furnaces and an extension to close off the south end of the east wall in c. 1960's.

Ross Cook, RCAHMW. 12th December 2012