In terms of both function and structure, the Lowry is not one building but five: the 1400-seat Lyric Theatre; a 400-seat adaptable theatre; a gallery for hands-on children's art; a gallery for Lowry's paintings; and a tower in which there is storage for paintings and other art.
The superstructures for all the building's elements are composite steel/concrete structures. The most challenging is the Lyric Theatre. A 25m high concrete wall encloses the whole theatre, and at the front foyer it slopes upwards and outwards. Punching through are the main staircases to the upper tiers. Its vertical sides at the junction with the flytower restrain the wall. The two internal upper seating tiers are steel structures supporting pre-cast concrete floor units, through which ventilation air flows from the air plenum within the steel cantilever frames. The internal steel frame and cantilever floor tier supports work compositely with the concrete wall.
At the Children's Gallery, the elevation is formed with a full-depth structural truss that supports both roof and floor. The roof is a steel frame on a triangular module with plant rooms embedded within the triangles.
The structure of the horseshoe-shaped Quay Theatre has been significantly enhanced using fire-engineering techniques. Seating tiers are a steel frame with steel/concrete floor pans, the whole hanging from the substantial steel roof structure. A concrete wall around the auditorium fulfils acoustic separation needs as well as supporting the roof. Buro Happold's fire engineers, Fedra, proved that none of the steel seating structure requires fire protection - fire load is low, there are no windows to allow an inrush of air, and the auditorium volume is large, keeping temperatures down.
In the Lowry Gallery the walls that form the open-topped internal rectangular spaces are known as 'fat' walls - they contain the ventilation ductwork that provides the high-level supply air, and also are structurally stable by means of their depth.
A true composite structure, the tower has a central RC lift-shaft and stair core, and RC floors with a spiral external steel frame formed from column sections.
Beneath the centre of these complex structures is the basement, which almost fills the triangle of the site between the dock walls and the Ship Canal. A diaphragm wall bounds the basement, toed into the clay above the underlying sandstone.Waterproofing is by Voltex - bentonite clay granules in a geotextile - which is sandwiched between the diaphragm walls and an internal RC wall, forming the inside of the basement. Substantial existing foundations from the previous nineteenth century warehouses had to be bridged over and sometimes removed during the foundation piling operation - piles founded and socketed in the sandstone which underlies most of Salford.