Grade II* listed building. Main construction periods 1821 to 1826 Summary from record TQ 97 SW 1042: Building 26 was erected as part of the reconstruction of the dockyard begun in 1813 and completed in 1830. It was constructed between 1823 and 1826 as a working mast and boathouse ans was one of a pair of buildings erected either side of a mast-pond; the other being a mast store. The building was constructed of yellow-brick, is supported by cast-iron cloumns and beams and had an iron, multi-valley roof. It is used today as a warehouse.