Aircraft Hangar No. 6, R.A.F. Station, Crumlin Road, Aldergrove, Co Antrim

Aircraft Hangar No. 6, RAF Aldergrove

This large aircraft hangar stands near the entrance to RAF Aldergrove on Crumlin Road, Co Antrim. Though extensively refurbished in modern times, it is listed for its structural and historical significance, particularly as a surviving example of the "Belfast" roof truss — a distinctive timber truss design developed around the mid-nineteenth century to achieve efficient, lightweight, longer roof spans in response to demands created by the industrial revolution. The truss is an efficient structural form, with a curved top member that functions essentially as an arch in combination with a horizontal tie member.

The building was constructed in 1920 as a remodelling of a much larger structure originally built in 1918. The original building measured approximately 167 metres by 45 metres, was open along its west side, and was roofed with timber Belfast trusses. In 1920, a hurricane substantially destroyed the original building. Following this damage, the site was reconfigured into a number of smaller buildings, of which only one continued to be used as a hangar — the structure now listed.

The trusses for the original roof were supplied by Harland and Wolff, the Belfast shipbuilders, though it remains unknown whether they were fabricated on site or transported from the shipyard, approximately 32 kilometres away. Parallel chord steel trusses supported the timber trusses above the door openings.

The current structure is a large, modern-appearing hangar with roof and sides finished in plastic-coated steel cladding. The western side is largely occupied by a set of large, modern full-height sliding doors.

Aldergrove is the oldest airfield in Northern Ireland. Selected by the RAF in 1917 as a possible pilot training school site, it was developed in 1918 by Harland and Wolff under Air Ministry auspices as an Aircraft Acceptance Park for assembling and test-flying Handley-Page V155 bombers. This use concluded in December 1919, after which the RAF maintained the base for training exercises.