The following text is from the original listed building designation:
TQ 9074 GREAT BASIN ROAD
Sheerness Dockyard
93/6/10004
Former working mast house,
Building Number 26
II*
Mast and boat house, now store. 1821-26, by Edward Holl, architect for the Navy Board, and John Rennie Snr, engineer. Yellow stock brick with slate hipped roof and internal iron frame. Rectangular open plan. EXTERIOR: 2-storey; 14x10-window range. North and east fronts have a ground-floor arcade of round arches with rubbed brick heads and iron fanlights, most altered or replaced, and rubbed brick flat heads to first-floor windows, larger hoist doors to the N side, 8112-pane metal tilting casement to the E; S front has ground-floor round-arched openings within recesses, blocked to the ends. E elevation obscured by later building, has wide flat-headed openings with large cast-iron lintels dated 1825, some containing double doors with small-paned lights above. Plat band, cornice and parapet. INTERIOR: contains an internal frame of ground-floor cast-iron columns with diagonal cruciform struts supporting longitudinal beams with parabolic bottom flanges, with lateral beams bolted along the sides, all with curved top profiles, with sockets in the sides holding joists, supporting timber boards. Upper floor has similar columns and braces bolted to valley beams, with 5-bay roof with trusses of cast-iron ties and struts with king and princess rods; 2 central bays have glazed ridges and the central area of first floor opened, all probably C20. A stair in the rear leads down to the culvert with iron gates formerly leading to the mast pond. HISTORY: one of two matching buildings used for constructing and storing masts and small boats, either side of a central mast pond, the second store and the pond now demolished and filled in. Built above a mast tunnel culvert leading from the river to underground vaults for storing masts under water, the latter also apparently filled in. The frame is part of an important strain in the early C19 development of metal and fire-proof structural systems, devised by Holl and used at the Devonport Ropery (1815), Chatham Lead Mills (1818) and subsequently Archway House, Sheerness (1825). The 1813 New Tobacco Warehouse, London (II*), used a similar system of diagonal cast-iron braces though to a timber roof. One of the last surviving dock buildings from Rennie's planned dockyard, and one of only two examples of a once-common naval building type. (Sources: Rennie Sir J: The Formation and Construction of British and Foreign Harbours: London: 1851:41; Sheerness, The Dockyard, Defences and Blue Town: 1995: NMR BI NO 93279).
Listing NGR: TQ9087474922 (3)

Description from record TQ 97 SW 1042:

Building 26 was constructed between 1823 and 1826 as a working mast and boathouse and 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, flemish bond on a stone plinth, supported by cast-iron columns and beams and had an iron, multi-valley roof. By the 1864 1st Ed OS map, due to technological changes, the mast-store on the north-east side of the mast-pond had been converted into an engineers shop and associated buildings built around it. None of these now survive. The mast-store was demolished in 1980 and the mast-pond filled in (although the mast tunnel leading to the mast-pond still had is gates in 1980) to make way for a modern warehouse. Building 26 is used today as a warehouse.(2)

Historic England archive material: AF1025500 RCHME: Sheerness Defences, Kent RCHME Cambridge surveyed the Sheerness Defences in 1994, as part of the East Thames Corridor Project.Contents : 5 plans, 2 overlays, 9 reports, 15 field record forms, correspondence, photographs, research material, survey dataCondition : INTACTMiniature Format Film Number: 223/Y,223/Z,224/A,224/B,224/C,224/D
BF093279 Sheerness Dockyard, Sheerness The material in this building file may also be duplicated in the individual site building files which are part of RCH01/108.The file contains the following miniature format film prints: 223Y/14 - 36; 223Z/0 - 22, 24 - 37; 224A/1 - 17, 19 - 33, 35, 37;224B/1, 3 - 9, 23 - 37; 224C/00 - 3, 10 - 16, 17A, 19 - 37; 224D/1 - 14, 16 - 36, 38; 243Q/16, 22 - 3, 28 - 32, 35; MF001896/0 - 11, 15, 20.The file also contains the following photographic prints: AA59/00803, AA59/00806, AA59/00809, AA59/00817, AA59/00820 - 22, AA59/00826 - 8, AA59/00832, AA59/00880, AA59/00886 - 7, AA59/00889 - 91, AA59/00893 - 5. National Maritime Museum photos - A2208, A1241, 3319, 4868, 7279 and also BL32372 f94, 32372 f96 and 21139 f8.There is a duplicate set of photojob 94/01964 included in this file as the original set has been subdivided into the various different sites which make up this buildings file.

<1> Not given, TQ97SW/109 (Map). SWX9401.

<2> Royal Commission on Historic Monuments in England, 1995, Sheerness: The Dockyard, Defences and Blue Town, NMR BI 93279 (Unpublished document). SWX6974.

<3> English Heritage, List of Buildings of Special Architectural or Historic Interest (Map). SKE16160.