The new enclosure is flanked on two sides by the L-shaped walls of the house and on one side by an original freestanding brick wall. A new glass wall incorporates a pair of motorised glass entrance doors that slides open against it.
The glass roof and its steel structure are independent of the walls. The structure consists of a single 450 x 250mm spine beam, stiffened to resist torsion.
It is supported at one end by a steel column against the house wall; at the other end it extends beyond the glass doors and rests on a skeletal steel 'tower'.
The tower is a three-sided, tri-girder truss structure of 50mm-diameter solid steel rods welded to the ends of 25mmthick triangular steel plates, which tapers to the top.
The spine beam supports a tri-girder truss that zigzags over the courtyard, tapering towards the courtyard walls to reflect structural forces. It is formed of three 50mm-diameter solid steel rods welded to a series of triangular plates which act as stiffeners. Above the spine beam, it is stiffened with additional steel plates welded along its length to resist deflection.
The truss extends beyond the glass doors to support the glass roof as a canopy.
A series of 120 x 80mm RHS purlins, each with a row of 60mm-diameter steel bosses welded to it, runs over the trusses. The 12mm-thick frameless glass roof panels are bolted to the bosses with 60mm-diameter patch plates.
The glass roof slopes towards the centre and runs into an aluminium gutter running above the spine beam. It discharges into the central support of the tower, a 120mm-diameter solid rod drilled with a 70mm-diameter rainwater outlet.