Green Roof Specialists

New Zealand Wide

Automatic Irrigation Systems

Waikato Region

GreenroofFAQ's

Do I need Council permission for a Green Roof?

The simple answer is yes, at this stage. You will, at the very least, require a building consent for the greenroof. Depending on what zone you live in, you may require a resource consent. It’s really a case by case issue so it would be wise to approach your local Council to check. Not obtaining…

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Why would I want a green roof?

Extend the life of the roof and waterproof membrane. Reduce storm water run-off. Improve thermal performance of the roof. Improve habitat for birds and insects. Absorb carbon dioxide and reduce greenhouse gases. Improve acoustic performance. They look great.

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How often does maintenance need to be carried out?

Generally, 3-4 visits in the first year. 1-2 visits for subsequent years.

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How much does a green roof cost?

The cost of a green roof generally starts at around $200 per square metre to supply, install and maintain for the first 12 months an extensive green roof. The factors affecting cost include craneage, size, location, height, layout and type of green roof required. Contact us for more information.

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What are the rates of coverage for each system?

Plug planted roof will achieve 80% plant coverage 9-12 months after installation

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Could I use NZ natives?

Yes there are many NZ species suitable for roof planting. However the growing medium substrate needs to be deeper than for sedum and they will require more maintenance.

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How are the plants installed?

Depending on site conditions, plant selection, rates of coverage required and budget. The first option is hydroseeding/planting; cutting material and seeds are spread on the prepared substrate, seeds germinate/cuttings root and the plant layer establishes over time. Option 2 is plug planting – young plants are manually installed into the substrate at the given density…

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Do you use the same system on all roofs?

No. The design of each system with regard to build up and plant selection will vary for each roof. As well as client demands and budget, factors taken into account include building location, surrounding environment, and orientation of the roof and localised microclimates on the roof.

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Are there proven, scientific standards for green roof design?

Presently, the only widely accepted, established standards for green roof construction are those developed in Germany by the Forschungsgesellschaft Landschaftsentwicklung Landschaftsbau.(FLL)These standards and guidelines are comprehensive, and include industry standard tests for the weight, moisture, nutrient content, and grain-size distribution of growing media. FLL also certifies laboratories to conduct critical tests, such as the root…

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Does the roof have to be flat?

No the plants and substrate will be stable and successful at pitches up to 30 degrees

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Can I put a green roof on my existing residence?

Many people have realized the benefits of a green roof on their own home. For either existing dwellings or new construction, one should always consult a structural engineer to determine the structural requirements of a green roof.

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Can people walk on the green roof?

Generally, extensive green roofs are not designed for pedestrian traffic. But the occasional incursion by an inspector or maintenance worker would not be a problem for most commonly used plants.

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Do leaks and other problems occur?

Greenroofs protect the waterproofing from ultra-violet radiation and thermal shock. These are the two main elements that age and eventually cause the waterproofing to fail. It is generally accepted that installing a green roof will double the estimated life expectancy of a newly installed waterproofing system.

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Where can I see an existing green roof?

Greenroofs Ltd have worked on the Waitakere Civic Centre green roof in Henderson and University of Auckland’s green roof trials at the School of Engineering. In addition there are many other existing green roofs such as the Hundertwasser toilets in Kawakawa, Maori Bay, Muriwai public toilets or the Auckland Botannic Gardens.

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Are they always green?

No! Many greenroofs appear red, orange, yellow and all colours in between at different times of the year because the fleshy leaves of various succulents change colours throughout the year. Also, greenroof plants are not all evergreen, nor should they be. The beauty and anticipation of the change of seasons add to the colour palette….

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Do I need to water it?

Yes – we have found that we are unable to warranty a green roof installation unless it has some kind of simple automatic dripline irrigation system.

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How much does it weigh?

The maximum weight of a fully saturated extensive green roof (75mm depth of growing medium) i.e. all the material above the waterproof layer is 100 kg per square metre.

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What are the different types of Green Roof?

Green roofs are classified as either extensive or intensive. Extensive green roofs are lightweight and low maintenance. They are usually inaccessible and are therefore planted with drought-resistant species, which survive on rainwater. Intensive green roofs require comprehensive maintenance. Because intensive green roofs are often accessible and more elaborately planted, buildings must be able to bear…

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What is a Green Roof?

Roofs that are either partially or completely covered with plants are considered green roofs. While green roof technology is somewhat new in NZ, European countries, in particular Germany, have been designing green roofs for decades. Each particular green roof varies, however, every green roof contains the following basic components: waterproofing membrane, root barrier, drainage and…

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