Auckland Library and the Growth of Green Roofs

What started as a standard refurbishment and repair, evolved into a unique opportunity to create a living green roof with over two thousand low maintenance native New Zealand plants installed so far and with a further 300 to 400 plants being planted over the coming months to improve the overall coverage.

Choosing the right waterproofing system was without a doubt one of the most important steps toward the goals of preserving the iconic building, its heritage, and its contents for many years to come and allowing the development of a roof garden aimed to extend the roof's lifespan, improve stormwater runoff, air quality and to set the example for other business and councils going forward.

“The living roof will have a range of benefits, including reducing stormwater runoff, improving air quality, protecting the roof membrane from solar damage, and increasing biodiversity and habitat opportunities for insects and birds," says Auckland Mayor, Phill Goff. "It will be an example to other property owners in the central city to investigate installing green infrastructure, which as well as the environmental benefits, will help make our city centre a more pleasant place to work, shop and visit.”

Auckland Council project manager Rachel Devine said the living roof “seemed like the perfect opportunity to leverage and enhance the much-needed repair works."

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 by experienced installers Sansom Construction Systems Ltd.

The existing old membrane was removed in its entirety, the exposed concrete was cleaned and prepared for the application of Hydrotech MM6125. The roofing areas, parapets, and main plant room roofs were waterproofed with a combination of Hydrotech and Casali membranes.

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 has been able to work closely with the Babbage Consultants and applicators Sansom Construction Systems Ltd on the green roof design requirements, providing the necessary support and technical expertise throughout the project.

"Sansom is very proud to have been part of this iconic project with Allco Waterproofing. Allco’s Hydrotech was selected as the ideal membrane due to its proven track record on zero fall roofs and green roof overlay," says Steven Van Rhoon, Director, Sansom Construction Systems. "The continued support and input from Allco’s Technical Advisors and Sansom’s experience, in combination with selecting the right waterproofing membrane, were key factors in the project’s success."

With increased demand for high-density housing and the push for greener cities, the hundreds of unused building rooftops present a perfect opportunity to change and make improvements now. Green roofs provide the space, sunlight and fresh air plants need to thrive whilst creating community spaces and allowing the growth of native New Zealand plants.

Green roof installations like Auckland Library have a proven return on investment beyond environmental benefits. To find out more about these benefits, read Allco's article, Green Roof Benefits Far Exceed Sustainability.

For all advice and support contact Allco’s technical team at [email protected]

Hydrotech Monolithic Membrane

Allco Waterproofing Solutions

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Hydrotech Monolithic Membrane 6125 (MM6125) is a thick, tough, flexible, self-healing membrane for use in roofing applications.

1. Hydrotech (MM6125) membrane system has been assessed as a waterproofing membrane solution for use in cold roof and deck assemblies, and Protected membrane roof and deck (PMR) assemblies.

2. The system must always be protected as follows:

a) On PMR assembly: one of the following overlays must be installed over the insulation layer
- Pavers or floating timber deck on pedestals
- Ballast (graded stones)
- Green roof
- Concrete topping slab
b) On a trafficable cold roof/deck assembly: one of the overlays described in 2(a) must be used:
c) On a non-trafficable cold roof/deck assembly or where only maintenance related traffic is expected: the membrane must be protected with a layer of Hydroflex 30 or Casali Olympia.

Pavers or floating timber deck on pedestals
Ballast (graded stones)
Green roof
Concrete topping slab

3. The system will resist the effects of wind uplift likely to occur in practice. The effect of wind on the overlays described in 2(a) falls outside the scope of this certificate.

4. The system may be used on buildings within the following scope:

a) On new buildings or existing buildings in all exposure zones, excluding microclimates, as defined by NZS3604: 2011.
b) On reinforced concrete substrates with any pitch including zero pitch defined as less than 1:100/0.5, gutter fall must be maintained at a minimum of 1:100/0.5

See CodeMark certificate for full information.

If designed, used, installed and maintained in accordance technical literature and manufacturer's instructions Hydrotech Membrane (MM6125) System will comply with or contribute to comply with the following provisions of the NZBC:

Clause B1 STRUCTURE: Performance B1.3.1, B1.3.2, B1.3.3 (b), (c), (f), (g), (h), (m), (n), (q), B1.3.4 (b), (c), (d), (e)
Clause B2 DURABILITY: Performance B2.3.1 (a) where ballast, green roof or concrete topping slab are used and B2.3.1 (b) where not, B2.3.2 (b)
Clause E2 EXTERNAL MOISTURE: Performance E2.3.1, E2.3.2, E2.3.7 (b), (c)
Clause F2 HAZARDOUS BUILDING MATERIALS: Performance F2.3.1

See CodeMark certificate for full information.

CodeMark

Casali Torch On

Allco Waterproofing Solutions

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Casali is an Italian torch-on roofing membrane made of pure bitumen with the highest quality techno-polymers.

Casali Roof and Deck Membrane Systems have been appraised as roof and deck waterproofing membranes on buildings within the following scope:

the scope limitations of NZBC Acceptable Solution E2/AS1, Paragraph 1.1; or,
the scope limitations of NZBC Acceptable Solution E2/AS1, Paragraph 1.1 with regard to building height and floor plan area when subject to specific structural design; and,
with substrates of plywood, fibre cement compressed sheet or suspended concrete slab; and,
with minimum falls for plywood roofs of 1:30, concrete roofs of 1:60 and decks of 1:40; and,
with deck size limited to 40m² and,
situated in NZS 3604 Wind Zones up to, and including, Extra High.
situated in specific design wind pressures up to a maximum design differential Ultimate Limit
State (ULS) of 6 kPa with the weathertightness detailing subject to specific design.

Casali Roof and Deck Membrane Systems have also been appraised for use as roof and deck waterproofing membranes on specifically designed buildings within the following scope:

With building structures designed and constructed to comply with the NZBC; and,
With roof and deck supporting structures of timber framing with substrates of plywood or fibre cement sheet; and,
With substrates of suspended concrete slab; and,
Subjected to maximum wind pressures; and,
With the weathertightness design of all junctions being the subject of specific design by the designer.

In the opinion of BRANZ, Casali Dermabit/Dermafil Roof and Deck Membrane Systems, if designed, used, installed and maintained in accordance with the statements and conditions of this Appraisal, will meet or contribute to meeting the following provisions of the NZBC:

Clause B2 DURABILITY: Performance B2.3.1 (b) 15 years and B2.3.2. Casali Dermabit/Dermafil Roof and Deck Membrane Systems meet this requirement. See Paragraph 10.1.
Clause E2 EXTERNAL MOISTURE: Performance E2.3.1 and E2.3.2. Casali Dermabit/Dermafil Roof and Deck Membrane Systems meets these requirements. See Paragraphs 13.1–13.9.
Clause F2 HAZARDOUS BUILDING MATERIALS: Performance F2.3.1. Casali Dermabit/Dermafil Roof and Deck Membrane Systems meet this requirement.

Casali Dermabit/Dermafil Roof and Deck Membrane Systems have been appraised as an Alternative Solution in terms of New Zealand Building Code compliance. The membranes are an alternative to the membranes specified in NZBC Acceptable Solution E2/AS1, and an Alternative Solution subject to specific design for other buildings not covered within E2/AS1.

BRANZ Appraised

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