Hangar 4 at former RAF West Raynham

Hangar 4 at former RAF West Raynham is a Type-C Aircraft Hangar with annexes, constructed between 1936 and 1939 to Air Ministry drawings 5053/36 and 5054/36.

The building is principally constructed of 14-inch reinforced concrete walls with a steel roof structure covered in asbestos slates. The long side elevation faces the flying field. At each end are full-height steel doors running to external gantries. Annexes are positioned on both the flying field side (for squadron offices) and the opposite side (for workshops and stores).

The roof is concealed behind a parapet with a later metal balustrade. It comprises a series of transverse ridges with hipped ends, covered in asbestos cement slates. The long side walls are built of plain concrete with a slightly bush-hammered surface. At mid-height are ten large window openings separated by concrete piers; the original Crittal multi-pane casements have been replaced with late-20th century glazing. One bay at each end, slightly brought forward in a Moderne manner with a higher parapet, features a tall single light with horizontal bars centred to the bay. Facing the flying field, a very large number 4 is painted centrally at parapet level.

The end elevations have six full-height and full-width steel doors with replacement glazing at the top, under a deep projecting rail carrying the rolling headgear. Beyond each opening a light steel lattice beam projects out, carried by light steel strutted support with ground-stops for the doors. Above the doors, contained by wing walls of the first bays, there is a deep apron with hanging asbestos-cement slates at the west end; at the east end these have been replaced with corrugated asbestos-cement sheet. The east doors have a water tank added at high level. The western end has a roller shutter inserted between the opened doors, which are otherwise fully retained.

Single storey annexes occupy each of the long side elevations. The southern office annex has had every window and door replaced with uPVC units. The northern workshop annex has also had most of its doors and windows replaced with uPVC, though an earlier set of rubber doors has been retained at the central entrance and one doorway has been infilled. The north elevation is the most altered of the four hangars at West Raynham. An historic extension to the workshop annex runs along the three western bays, built of brick and covered in pebble-dash render. Six of the upper windows have been partly-infilled to accommodate post-World War II boiler units, installed by the USAF. A large amount of 21st-century mechanical equipment and plant has been erected on the north side of the building, with various flues and ducts running into and out of the hangar walls. At the eastern end of the north elevation is a covered single-storey cage-like structure, possibly a store or dog kennel.

The principal interior space, the hangar itself, is twelve bays long and has no structural subdivisions. A large number of free-standing units have been created within the hangar as part of the building's 21st-century use as a manufacturing business. The complex lattice of roof girders remains visible, along with the roofing boards above it, some of which are stained from fire damage. There are four gantry cranes with surviving mechanisms at bays 2, 6, 7 and 11, capable of carrying either 1.5 tons or 6 tons as indicated by surviving signage. The steel structure supporting the roof is buried in the reinforced concrete walls, except for additional structural support in each of the end bays. The floor is formed of plain concrete.

Access to the annexes is gained through multiple doorways on the north and south sides of the building. Centrally on each side are massive metal fire doors which originally led directly outside and now lead to enclosed spaces.

The northern annexes originally housed workshops, stores and storage tanks. They have undergone various other uses since then but retain much of their original layout as well as heavy metal doors, radiators and windows. Some historic workshop benches survive. One room with a metal door and a spy-hole may historically have been an armoury.

The southern annexes, facing the flying field, were originally intended to house squadron offices. Most of the plan form has been lost as these areas have been modified to accommodate 21st-century open plan offices and showrooms.