Laboratory Five was a vibration test building. It comprises a deep chamber for testing within, enclosed by thick reinforced concrete walls and a concrete roof. Two brick plant rooms are located to the south and east of the cell.
600mm reinforced concrete walls surround the chamber, on top of which sit 16 square columns. These support a shallow rectangular tray strengthened by deep beams spanning the width of the roof.
Shingle on the roof provided ballast to reduce the spread of blast material. Columns were not fastened to the walls below to allow for collapse in the event of an explosion from within. Between the columns dual layered polycarbonate, used to achieve atmospheric pressures, was tensioned against metal blades and would shatter in a blast.
Walls sit on a reinforced concrete raft that bears directly onto the shingle bed. Shingle is banked to the building on the north, east and south sides with the intention of absorbing a possible shock wave.
The internal walls of the chamber contain horizontal and vertical shallow steel plates to allow for machinery to be fixed within the structure. 1.5m below this, is the lift pit floor for positioning heavy test equipment. A narrow gallery runs around the chamber on three sides to provide access to machinery mounted high within the lab.