A sloping roof with an aluminium soffit
The roof appears to float over the gallery without any visible means of support. The structure is concealed. A series of canted 120 x 80mm RHS steel beams rest at one end on the top of the garden wall; at the other end they are supported on tubular columns concealed within the oak door frames. Each beam cants up over the rooflight and turns down to create the slope of the aluminium-faced roof, forming a shape similar to an insect leg. The beams are braced by pairs of 152 x 152mm UC purlins which run from the house wall to the orangery wall.
The structure is clad with plywood sheets which create the sloping and tapered profile. They are partly filled with insulation. A Sarnafil roof membrane provides the waterproof layer. The ceiling is lined with 1m x 1m x 3mm flat aluminium panels, spray-painted silver, which are glued and screwed to the plywood with a 6mm shadow gap. The aluminium nose-cone is fixed in sections with dry open joints between, and screwed top and bottom through the roof covering to aluminium flats which are bolted to the ply
The south wall, 20m long, consists of six 4m x 2.5m x 19mm glass sheets, thick enough to act as rigid sheets, so toughening was not necessary. They are positioned in pairs between 950mm wide oak doors. Each door consists of a 25 x 25mm RHS steel framework and 25mM ply core faced both sides with 125 x 25mm oak boards. The framework is fixed to a a ball-bearing race welded to a 76mm diameter CHS column, allowing the door to pivot. The columns are faced with curved sections of oak. A pin connector at the top of each column gives support to the cranked beam roof structure.