Originally completed in 2022, the 500m² green roof was designed not only to enhance the city’s sustainability goals but also to function as a research platform for understanding the performance of living roofs in New Zealand’s urban context. Allco supplied the critical waterproofing system that supports the integrity of the structure beneath the vegetation layer, ensuring long-term performance under demanding environmental conditions.

Performance findings that matter to specifiers

Monitoring has shown that the living roof:

• Delays and reduces peak stormwater runoff: The Roof captures 80% of rainfall during heavy downpours and almost every drop in light rainfall, considerably reducing the volume discharged to the stormwater network.
• Significantly reduces rooftop temperatures: During the hottest months, the green roof reached surface temperatures of around 25°C, compared to up to 47°C on conventional roofs, demonstrating its ability to moderate building heat gain.
• Improves urban biodiversity: The roof is being used by birds, insects, and pollinators, contributing to urban ecological resilience.
• Enhances roof membrane protection: Extending its service life through insulation from UV and thermal cycling.

These findings demonstrate that green roofs aren’t just a design trend; they’re a technically proven, high-performance solution for urban resilience, stormwater management, and building efficiency.

Allco’s role: Waterproofing for longevity and confidence

Choosing the right waterproofing system was undoubtedly one of the most important steps toward preserving the iconic building, its heritage, and its contents for many years to come.  

The library’s zero fall roof set up and green roof requirement meant Allco’s Hydrotech membrane was the ideal solution for the ambitious project, with the installation carried out by our experienced installers, Sansom. 

A large portion of the roof area is covered by garden systems and the remaining areas are covered by gravel ballast providing both aesthetic appeal and protection for the waterproof membrane against foot traffic. 

Allco worked closely with Babbage Consultants and applicators Sansom on the roof design requirements, providing the necessary support and technical expertise throughout the project.

Build greener from the roof down

Whether you’re designing for stormwater compliance, urban cooling, or enhanced building performance, green roofs can help meet multiple objectives at once, with systems backed by data and real-world performance. 

Talk to Allco’s team today about green roof solutions that work, designed to support your specs, your project, and the environment. 

Recent findings, published by Auckland Council here.