Z House is a Christchurch residence designed by RTA Studio following the loss of a multi-generational family home during the 2011 Canterbury earthquake. The new home responds to the need for resilience in the face of seismic and flood risks, while incorporating elements of the original structure into a future-focused design.

The brief called for a permanent and energy-efficient building that would minimise environmental impact over its lifetime. Thermal performance and durability were key considerations for the roof design, which required a low-maintenance, high-performing solution that also met the aesthetic goals of the project.

To meet these requirements, RTA Studio specified the Duotherm Warm Roof system from Equus Industries. The system comprises a vapour barrier, thermal insulation, and a two-layer waterproofing membrane. Together, these layers contribute to a consistently dry and well-insulated internal environment.

Project-specific condensation risk analyses were undertaken to ensure the roof delivered appropriate thermal resistance and control of internal moisture. This level of thermal performance supports the home's energy efficiency while reducing reliance on mechanical heating and cooling over time.

For the roof surface, RTA Studio and the client selected a black cap sheet from the Duotherm system. The cap sheet provides a refined finish and creates a subtle glimmer in sunlight. The design also included integrated solar battens, carefully detailed terminations, and circular roof penetrations to allow planting to grow through. Close collaboration between RTA Studio and the Equus technical team ensured these elements were resolved with precision.

Installation of the roofing system was carried out by Canterbury Waterproofing Ltd, a certified Equus applicator. Regular quality assurance inspections were completed during installation by both RTA Studio and Equus consultants.

Z House demonstrates how a warm roof system can contribute to long-term sustainability, aesthetic refinement, and resilient performance in residential design.