The redevelopment of the 45-year-old science precinct building at the University of Otago was way overdue, with the roof in desperate need of some serious TLC.
The existing building had a zero degree concrete slab roof with a leaking bitumous membrane. Weight concerns and significant plant and ventilation requirements meant the options were limited as to which system to install.
The roofing system needed to be robust and possess the design flexibility to successfully waterproof the 200-plus penetrations of various sizes made by the significant extraction systems used to ventilate the faculty’s precious equipment. Alternative cementitious screed systems were considered for creating the required falls, but they would have been too heavy and were considered less practical in terms of the application required in these circumstances.
Using clause E2/AS1 of the Building Code as a benchmark, the architect specified that the dead flat (zero-degree) concrete slab roof substrate be cladded with a roofing system sloped to a minimum of two degrees.