Royal Arsenal Building 41 And 41A Royal Laboratory Square

Royal Arsenal Building 41 and 41A, Royal Laboratory Square

This ordnance factory and workshop complex, originally built for ammunition manufacture, comprises ranges of brick buildings surrounding a quadrangle, sited north of the original Royal Laboratory buildings of 1694–96. The west range dates from around 1805, while the east and north ranges date from around 1810. The south range was constructed in three phases from 1878 onwards as a carpenter's workshop and later for packing ammunition into boxes and barrels.

The east, north and west ranges are constructed in Flemish bond yellow stock brick with Portland stone plat bands, cornicing and dressings. Roofs are hipped slate and felt. The layout was originally open to the south and represents a significant surviving example of a large industrial layout from this period.

The east range is two storeys with a symmetrical 15-window elevation. The centre projects slightly with a pedimented 5-window range, a plat band and moulded eaves cornice. The ground floor features round-arched cast-iron windows set in round-arched recesses with a partly blocked central archway leading through to the quadrangle. The first floor has flat arches over 12-pane sashes; the rear elevation is similar. A parapetted extension at the north end, dating from 1854, previously housed a beam engine. This extension has taller ground-floor windows and blind panels at the centre. Behind it stands a three-storey former boiler house with 6/6-pane sashes. The interior contains an 1854 arcade of cast-iron columns with flanged capitals on both ground and first floors, supporting mid-19th century queen post trusses. Cast-iron columns were inserted into the east range around 1854 to support the conversion to steam power.

The north range was originally two storeys but was heightened in the early 20th century with an upper storey added in mock timber frame. It has nine-window elevations similar to the east range but without a pediment. The windows were replaced in the early 20th century. The interior was gutted in the early 20th century but retains a lateral spine wall.

The west range has a pedimented east elevation facing into the courtyard, identical to the facing west elevation of the east range. The west elevation was rebuilt and rendered in the mid-20th century. The interior has been gutted and fitted with an internal concrete frame.

The south range (41A) is of cast-iron frame construction with brick infill and corrugated iron sheet cladding, topped with a corrugated sheet north-light roof. It consists of parallel ranges of arcades. The central two bays date from 1878, with a two-bay-wide extension of around 1890 on the north side and a two-bay-wide extension of 1900–31 on the south side. The exposed iron frame comprises octagonal columns with small capitals. The upper section is bolted to two-ply longitudinal beams with quadrant curved ends and openwork spandrels. Two octagonal sockets in the upper sides connect to north-light trusses with wrought-iron bars. Holes in the lower side accommodated supports for the former line shafting used in manufacturing.

The complex represents a significant surviving example of a large 19th-century industrial layout. Although heightened in the early 20th century, the north range retains substantially complete elevations up to the former cornice level. The east range is the most complete and provides important evidence of the group's conversion to steam power for manufacturing ammunition in 1854. The iron-framed ranges to the south form an integral part of the factory's expansion in the later 19th century.