Houses affected by weather events could be resource for a more sustainable future

Friday, 6 March 2026

As cities around the country brace for increasingly frequent floods and cyclones, and more homes are deemed unsafe and red-stickered by councils, a pressing question will be what to do with the materials from these storm-damaged homes?

After having been through Cyclone Gabrielle and floods of Auckland Anniversary weekend, Auckland Council has red-stickered 1200 homes and is working with a team from University of Auckland Architecture to help reuse materials from them.

In Auckland, 1200 Category 3 homes could potentially be removed across the region in the wake of the 2023 storms, say Auckland Council.

Of those, 554 have been removed so far, with 30% of those removed being relocated, to date. The remainder have been deconstructed with a focus on reusing and recycling materials.

According to Mark Roberts, Senior Waste Planning Specialist of Waste Solutions at Auckland Council, construction and demolition waste makes up at least 30% of all material going to landfill - so this is a critical area for the council to address as it works towards its goal of zero waste by 2040.

“If all 1200 cyclone and flood-damaged houses were demolished, we estimate up to 70,000 tonnes of material would have to be disposed of. That is exactly what we are trying to avoid,” he says.

Relocation and deconstruction provide far better outcomes, and relocation, in particular, has clear financial and economic advantages, he adds.

Roberts has commissioned a team lead by University of Auckland Associate Professor Mike Davis to create an “urban mine” of recycled materials from these red-stickered homes which reuses as much as possible.

Davis, who works in the Auckland University’s Māori and Pacific Housing Research Centre MĀPIHI, and Future Cities Research Centre, is mapping what materials have come out of Auckland’s red-stickered houses and where the materials have gone.

“Then we can start to predict what might come out of houses that have been red-stickered or that are damaged in storms in the future,” he says.

The Auckland University team is breaking these red-stickered homes down in terms of type - certain era homes produce a lot more stuff for landfill than others.

Hand-held devices and drones are making 3D scans of different era homes from modern homes built in sub-divisions to villas and bungalows.

“Building a knowledge bank of the reusable materials available from red-stickered houses will help the construction industry know what materials are likely to be available for reuse,” says Davis.

He adds that older houses tend to have richer, more valuable materials like kauri, matai and rimu timber. “More than 50% of timbers can often be reused from earlier buildings.”

Many homes built from the 2000s onwards, on the other hand, have a lot of materials which are glued together and are much harder to reuse, he says.

“If something can’t be quickly pulled apart, it just goes to landfill, so it’s just about applying what architects design, for disassembly.“

The Auckland University project will highlight any environmentally harmful materials coming out of cyclone-devastated houses.

“One example is polystyrene which doesn’t go away, so when a house comes down after 50 years, it’s a massive problem,” says Davis.

The associate professor has his own opinions about the process of red-stickering homes as more storms hit the country on a regular basis. He thinks there are many different ways to deal with damaged and flooded homes and that more experts should be involved with the decision of what happens to them.

“It needs to be consultative and inclusive with designers, planners, architects and iwi who have this depth of knowledge about the land.”

New homes built for easy assembly and disassembly

Both Davis, his colleague Professor Andrew Barrie, and Auckland Council’s Mark Roberts agree that new homes should be as easily disassembled as possible and generally more adaptable, which will help to future-proof housing.

If homes in Auckland were more easily disassembled and their components reused, “that would significantly reduce waste and mitigate the environmental impact when severe weather events occur,” says Roberts.

Professor Barrie gives the example of the German auto industry where the government legislated that cars had to be completely pulled apart for components.

“They just redesigned the cars so you could unclip them. Everything that was done could be undone,” he says.

“In houses we don’t do that. There are heaps of things that only have one use, like gib and flooring.”

The building industry at the moment has a “rip, strip and bury mentality,” says Barrie.

“So it’s about applying design for disassembly.”

Davis is hoping the red-sticker recycling materials project for Auckland Council will lead to greater quantities of building materials becoming available at recycling centres and demolition yards.

“The aim is to normalise the idea of buying second-hand materials and seeing that as a positive thing.

“We’re moving away from the idea that everything has to be new, new, new, because that’s resource intensive and not sustainable.”

Results from the research are expected early this year.