The building is of steel frame construction, combined with a TATA steel structural deck and an 18mm structural plywood deck on the main roof area and adjacent walkway terrace. Upon completion of the structural deck, a high-performance felt system was installed, including a tapered insulation scheme. The leading edges of the building were fitted with aluminium capping around the perimeter of the roof parapet upstand. Once the waterproofing was complete, lightning conductor pads were laid across the roof field area. The works were carried out while the hospital remained open to the public, with additional care taken to ensure minimal disruption to both the public and staff.