Chapel Mills, American Wharf

Chapel Mills, American Wharf is a complex of buildings comprising a steam mill, bakehouse, and grain store, dating back to 1781. It was originally built by Aaron Moody and Christopher Potter to produce biscuits for the Royal Navy during the American War of Independence. The complex was extended between 1800 and 1811 to increase victualling for the fleet during the Napoleonic Wars, and again in 1869 when some original timber posts were replaced by cruciform cast iron columns. In the 1920s, iron-framed windows were inserted into the south elevation.

The original 1781 building is three storeys high and constructed of brick in a Flemish bond pattern, with a hipped roof (in four hips to the east front), now pantiled. The south front features two windows; the top floor and one first-floor window are original sashes, while the others are casements with cambered head linings to the lower floors, incorporating oval-shaped iron ties. The east front has four original pivoting sashes and a gabled wooden hoist to the north end. The interior retains original wooden aisle posts, although the ground floor has cruciform cast iron columns inserted in 1869.

Attached to the north and west is the bakehouse and grain store extension, built between 1800 and 1811. The west front was stuccoed in the 1930s. The roof is plain tiled to the south and pantiled to the west. The west front incorporates a former three-storey domestic building with three bays, featuring vertical details to the second-floor windows and six panes to the first-floor windows. The ground floor now has wider, 20th-century inserted doors. To the south of this is the former grain store, also of three storeys with attics, featuring four pivoting sashes and two gabled hoists with wooden doors to all floors, and cross-shaped iron ties. The south front has five 1920s iron-framed windows and oval and cross-shaped iron ties. The interior of the extension features cruciform cast iron columns installed in 1869 by the firm of Blumfield and Dalby, Southampton, with some original wooden posts still surviving against the walls.

James Watt described Chapel Steam Mill as having ten ovens, each discharging sixteen times daily and weighing three cwt of bread. It was the third steam mill built in the country and remains the sole survivor of the early generation of steam mills.