The 57,000-square-meter Commercial Bay project along the southern shore of the Waitemata harbor in Auckland, New Zealand, is set to be the largest mixed-use development in the city. Featuring a new 39-level office tower and 18,000 square meters of retail, Commercial Bay connects to an underground rail station and is expected to transform the waterfront from an aging mall into a hub for commerce, trade and transport.
With three basement levels more than 17 meters deep, waterproofing the Commercial Bay project required a solution that would work in a wet and muddy environment while addressing the complex architectural design featuring detailed interfacing. At the same time, the solution had to form a permanent, continuous seal against water and a barrier to resist the stress of ground settlement.
The new office tower was constructed among three existing buildings, making waterproofing a challenge due to the differential movement between buildings, which can damage the waterproofing if the design, or movement limiting structural designs, is not durable. Since the waterproofing application was scheduled to take place during the winter, with its heavy rainfall and high chance of mud contamination, the specifier wanted a solution that would be unaffected by the climate, and that would be fast and easy to install.
Simpson Gumpertz & Heger (SG&H), the structural design consultants on the Commercial Bay development, specified PREPRUFE Plus waterproofing membranes from GCP Applied Technologies (GCP) because they have a proven track record globally and in New Zealand. PREPRUFE Plus membranes were selected to protect the project’s basement and transport connection link. Sansom Construction Systems Ltd., a construction and engineering company, delivered the solution after consulting with developer Precinct Properties.
“Time is important for us in construction,” said Elton Sturmfels, owner of Sansom Construction Systems Ltd. “The PREPRUFE Plus system was easy and fast to install, especially when compared with competitors’ systems. This was especially evident during bad weather periods when it was significantly faster to apply the PREPRUFE Plus membrane than other underground waterproofing systems.”
Designed with Advanced Bond Technology and dual adhesive ZIPLAP seams, PREPRUFE Plus membranes form a unique, integral bond to poured concrete. This integral bond provides a robust barrier to water, moisture and gas, and prevents both the ingress and lateral migration of water. PREPRUFE Plus membranes are unique composite sheets comprised of a durable and flexible backing membrane, pressure-sensitive adhesive and patented, weather-resistant protective coating.
Another benefit of the PREPRUFE Plus products is their absence of a release liner. This aids with efficient and reliable installation. PREPRUFE Plus products require minimal cleaning before concrete pouring. Just a quick hose off is needed. The pre-applied waterproofing membrane can be trafficked immediately after application, and is ready for immediate placing of reinforcement. In addition, the PREPRUFE Plus membrane’s ZIPLAP seams allow for an adhesive-to-adhesive bond at membrane sheet overlaps and deliver superior performance in harsh conditions, without the need for specialized equipment, heat or power.
On the Commercial Bay project, the PREPRUFE Plus solution helped reduce installation time, cost and waste. Unlike alternatives that require special heating equipment to weld laps together, or detailing tape to seal the laps, the PREPRUFE Plus membrane’s easy roll and kick-out installation helped reduce installation time.
Adverse weather, mud contamination and delays to the construction schedule were major concerns for the developer, but since the PREPRUFE Plus membranes can be applied on damp surfaces, unlike alternative systems, the development was able to meet a tight construction schedule. In addition, the ease of removing mud and water from the membranes’ surfaces meant the contractor, Sansom Construction, did not have to worry about contamination issues.
PREPRUFE Plus membranes made waterproofing a complex design much easier and faster. GCP worked closely with SG&H during the design phase to identify 95% of structure’s details, and to outline the installation methods prior to starting the project. PREPRUFE Plus membranes were applied to provide comparatively simple but positive detailing on a multitude of piles, tiebacks, ground anchors and around penetrations. In addition, SG&H and GCP implemented strong quality assurance processes to ensure best practices and high installation quality. The robust waterproofing solution also helped rectify damages by other trades, such as during the installation of reinforcement, while maintaining waterproofing integrity.
“Since its introduction in the 1990s, more than 65 million square meters of PREPRUFE pre-applied waterproofing membranes have been installed and proven globally in a variety of climates, site conditions and facilities, including airports, museums, hospitals, stadiums as well as residential and commercial projects,” said Scott Whitelaw, technical and applications manager, Australia and New Zealand, GCP Applied Technologies. “The speed and ease of installing PREPRUFE Plus membranes was why it was selected to protect the acclaimed Commercial Bay development, a banner project that is transforming the city of Auckland.”