In 1936 the Imperial War Museum moved from Kensington to Kennington – to what had once been the Royal Bethlehem Hospital (aka Bedlam) for the insane. This handsome Georgian building on Lambeth Road became the principal storehouse and exhibition centre for a vast collection focused on all aspects of modern war.

In 1986 the Museum Trustees embarked on a three-stage redevelopment masterplan by Arup Associates to restore the building, improve facilities and increase display spaces. The final stage was the SouthWest Infill, a major and sensitive extension that has added 5,680m 2ofnew exhibition and education space over six floors. The Holocaust Exhibition occupies a major part of the space.

The new extension is constructed on top of, and adjacent to, the existing cinema. The existing steel lattice vault was extended 40 metres to the south and the existing western elevation continued to the south, in keeping with that of the original Grade II-listed building which dates from 1812.

Echoing, indeed continuing, the original, the new brick elevations are in yellow multicoloured stock brick with flat and semi-circular arches above windows in plain yellow brick. As in the original construction, the elevations are in nine inch-thick (215mm), Flemish-bonded brickwork using a lime-based mortar: this combination, the designers considered, allowed them to achieve the new 30m long, 18m high planes of brickwork without recourse to expansion joints.

A rigorous selection process followed to find a modern brick that would give a perfect match with the existing 19th century brickwork to the satisfaction of both the design team and English Heritage.

The chosen brick was a yellow multi-stock with the looks of a traditional London stock but the superior technical properties of a modern brick, including FL durability.

It produces an animated facade and a weathered appearance close to that of the original fabric. Other details were observed in equally meticulous fashion:

vertical gauging matches the imperial measure of the original while the horizontal gauging is in metric. The joints are finished with a weatherstruck profile and, reflecting the original, queen closers were used at the deep window reveals. The result is a barely visible transition from old to new that takes some really close inspection to detect.

PROJECT PROFILE

Client Imperial War Museum Architect Arup Associates Structural Engineer Arup Main Contractor Birse Construction Photography Nigel Spreadbury