2050 plants now call top of Auckland's Central City Library home

Kendall Hutt
Source: 1News

Atop the roof of Auckland's Central City Library, a total of 2050 native plants can now be found.

After climbing what is more like a ladder to the roof, what is known as a living or green roof is revealed.

A living or green roof are roofs which are partially or completely covered with vegetation and a growing medium, which is planted over a waterproofing membrane.

Living roofs may also include additional layers such as a root barrier and drainage and irrigation systems.

The living roof atop the library will enhance biodiversity, help to maintain temperatures in the building, and reduce noise levels by reflecting and absorbing sound.

It will also reduce stormwater run-off by absorbing 70% of total rainfall and it will also improve air quality.

The 2050 low-maintenance and hardy native plants have been planted in 560 "eco-pillows", which are mainly made from recycled polystyrene. The pillows incorporate a mix of soil and nutrients to keep the plants happy.

Once the plants have grown in the pillows weigh the same as the average washing machine.

Iwi Ngāti Whātua Ōrākei propagated the plants in their nursery and developed the design of the roof. The pattern is a form of weaving known as poutama, which represents growth, education and reproduction.

From above, the layout of the plants looks like a tukutuku panel found in a marae.

Ngāti Whātua Ōrākei also added plants to the roof which would have been on the original shoreline of the Waihorotiu Stream.

"It's an awesome way to express our rākau [plants] on the rooftop," Etienne Neho, Ngāti Whātua Pourewa Maara kai manager, told Breakfast.

"Not only is it a landscape feat as a green roof feature but it's a way for us to be able to restore the mauri within the CBD, within Tāmaki Makaurau and put the rākau or the plants that would have been here 150 to 200 years ago back into their natural place," he said.

"It's helping our waterways as well as our airways, so the more plants we have up on buildings, the better."

Neho said he would love to see the entire CBD planted as an urban ngahere.

"Instead of having buses and cars, I'd love to see trees down Queen St. I'd like to see this be a green oasis. If we start doing our part now, it'll make a massive difference for the future."

Mayor Phil Goff said it was the first time the council has created a living roof.

"It's environmentally sustainable and it's a very important part of what we need to do about the increasing global emissions and climate change."

Goff remarked it was an "ideal time" for other property owners in the city centre to install a living roof.

"This leads the way and I hope others will follow."

The living roof was installed as part of remedial work on the library's roof, which cost around $10 million. The living roof itself cost an additional $730,000 and took eight to 10 months to come to fruition.

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

The plants were craned onto the rooftop in pallets.

The vegetation is an alternative top layer to the usual stone ballast.

A further 300 to 400 plants will be planted over the coming months to improve the overall coverage.