We started in the ground by diverting the drainage and underpinning the existing foundations; creating as much space as possible. Reinforced concrete was used to form the basement and café structure and the floor to the theatre itself. This concrete provided a robust and durable structure, effectively tying the basement walls together. Above the concrete the solution changed to steelwork. A lighter solution was needed that could support the audience and technical areas. Again the structure is exposed, allowing it to become part of the technical canvas. A thin concrete transfer structure of composite asymmetric beams then caps the main auditorium and provides support for an acoustically separate floor to the upper areas. Above this a stressed-skin engineered timber roof encloses the top-floor rehearsal room.
There are no remains of the original building apart from the external wall and all support and stability systems were questioned and strengthened appropriately.
The auditorium is mechanically ventilated using displacement grilles mounted on the face of plenums located both behind and under the seat construction (stalls and balcony levels) and within the floor make-up to the side of the dropped seating area in the stalls. Flexible stage arrangements are key to the theatre and the scheme was developed to enable the supply air to be introduced into the space via combinations of the various plenums.
Environmental control within the remainder of the Egg is predominantly provided by the use of natural ventilation and low-surface-temperature radiators. Although relatively small in size, the Egg is equipped with all the complex performance lighting, audio-visual equipment and associated infrastructure that is to be found in much larger venues and these have been carefully integrated with the architecture