The Isaac Theatre Royal is one of Christchurch’s most iconic heritage buildings, and the Grade-A heritage listed theatre was badly damaged in the 2010 and 2011 Canterbury earthquakes. The project included the rebuild of a large portion of the structure while retaining the historic unreinforced masonry façade, ornate plaster ceiling dome and the entrance feature marble staircase.
Two major constraints on the project were the fixed $40M budget and the opening date for the first show. The theatre needed to be open for the 2014-2015 summer show season to keep key staff on. This required the design and construction to occur in two-thirds of the time of a conventional project. Holmes were the structural and fire engineers for the rebuild, and it became the first major entertainment venue to reopen for business in the CBD following the 2010 and 2011 earthquakes.
Holmes was brought into the project during construction to review the existing Fire Engineering Strategy provided by another consultant. Through performance based design we were able to present a robust solution on schedule and on budget.
The new Fire Engineering Strategy was produced within three months of engagement. The fire engineering design process also included:
- Collaboration with the University of Canterbury to develop a new egress modelling tool for Holmes Fire use, which could undertake the buildings comprehensive egress assessment of merging crowd spaces;
- Development of a fire strategy which considered an alternative compliance with the New Zealand Building Code in order to maintain the original architectural vision of a building designed over 100 years ago;
- A hands-on approach to proactively integrate the Fire Strategy with the operational needs of the Theatre.
- Consideration to Safety in Design, which included the physical practicality of installation and maintenance of the proposed fire strategy; and
- Implementation of a complex fire and security interface which included multiple tests and training of theatre staff.
The design team had a vision of reviving the building to its original design including several key heritage features such as the auditorium dome and plaster detailing, marble stairs, and Edwardian façade. The dome and plaster detailing, in particular, relied heavily on our assessment.
Using smoke modelling tools, we were able to eliminate the need for the existing motorised smoke curtains covering the full width of the theatre adjacent to the dome. This also allowed the client to remove all of the access gantries and maintenance of the system.
Throughout the project, we were able to work collaboratively with the client to provide a unique, performance-based solution tailored specifically to the needs of the heritage building.
The tight construction period was achieved through the use of information sharing with the contractor and other consultants in the form of 3D Revit models, a close working relationship with the contractor, and looking outside the box in terms of materials (such as shotcrete) and construction sequencing.
The Theatre’s fixed budget consisted of insurance money and various grants and fundraising commitments. A key part of managing the budget was cost certainty during the design phases. The use of 3D drawings allowed the quantity surveyors to more easily identify pinch points and difficult areas, especially with regard to conflicts with heritage fabric. This helped to identify, manage and reduce these high risk cost areas throughout the project.
Nearly all the unique heritage features of this building were saved and carefully restored by skilled craftsmen—leaving the theatre in a better condition than it was pre-earthquake.