Mark Roberts feels sorriest for those homeowners who’ve had an invisible $31,000 bill added to the construction costs of their new build – and don’t know about it.

“It’s one of the by-products of construction waste,” says Roberts, Senior Waste Specialist for Auckland Council, one of the people charged with minimising the massive amounts of waste going to landfill from the construction and demolition industry.

“There was an AUT study done back in 2016 which showed that, in every new [home] build, the cost of waste was an average $31,000 – and that preventable cost is simply added to the overall cost of the project.

“It is just sitting there, on somebody’s mortgage.”

Mark Roberts, Senior Waste Specialist for Auckland Council.

The size of the construction waste problem is already massive and is now being recalibrated. However, here’s what is known so far:

• At least 30% of all waste going to municipal landfills in Auckland is construction and demolition waste – materials like timber, plasterboard, concrete, metals and packaging.
• However, a June 2025 report by the Ministry for the Environment indicates that around 70% of waste going to all types of landfills across New Zealand is from construction, often this is soil contaminated by materials like asbestos and lead.
• The industry produces a total of about 650,000 tonnes of waste a year in Auckland.
• Each new home build produces, on average, four tonnes of waste. This is despite the fact that construction and demolition waste has the biggest potential for waste reduction through smart design, recycling and reuse.
• Up to 90% of the above waste can be diverted from landfill that way.

If waste soil is taken into account – and Roberts is in no doubt it should be – most of these figures will rise substantially.

First, however, Auckland Council is trying to work with the construction and demolition industry to voluntarily reduce the amount of waste and thus cost to clients, the community and the environment.

At a new development in Flatbush, Auckland Council GM Waste Solutions Justine Haves points out reusable items in a pile of waste.

The solution is surprisingly easy: simply design waste out at every stage of the build from concept to the point of handing over the keys. Every building design professional and contractor has a part to play.

“Traditionally, the finger has been pointed at builders. But it’s not just builders. Of course they have a role to play, but it’s really up to the whole industry – every link in the chain. It’s the architects, the structural engineers, the quantity surveyors, the people who specify what materials and quantities are to be used, the contractors and professional services people.

“The whole issue of waste needs to be factored into thinking right at the very beginning of the project, even the conceptual part, to the very end. It’s no good pointing fingers – what is really needed is a culture change throughout the industry.”

Nigel Benton is a Master Builder who is calling upon other builders to consider the impact construction waste has on their children and grandchildren, and to “give the sustainable path a go”.

“One simple way to minimise waste on a building site is having council rubbish, recycling and food scraps bins from the start so that all the food scraps, lunch packaging and drinks bottles are separated from the construction waste, which means it’s far less contaminated,” says Benton.

Nigel Benton, Master Builder.

“Materials chosen during the design and build process can also make a huge difference in reducing waste from sites.”

There are, Roberts says, some bad practices and attitudes that need to be addressed. “One example is what we call concrete cowpats. At the end of the concreting, the truck’s pipes must be cleared of all concrete. That leaves a lump of concrete that looks like a cowpat – and you find them in gutters, on berms, on neighbouring properties, even in reserves.

“Another example is litter that isn’t contained and escapes from building sites. This can include materials such as sawdust, packaging and polystyrene as well as dropped litter such as cigarette packets and drink bottles. This will often find its way into local streams – and it has a bad effect on wildlife and ecosystems. The community finds that distressing.

“People associated with the construction industry do a very good job but their attitude is often ‘just get the job done’ – and that promotes short cuts.”

Roberts says some companies have already taken steps to address waste, like Naylor Love and Cook Brothers. Auckland Council provides a Waste Minimisation & Innovation Fund (WMIF) to help fund sustainable waste schemes and innovative products to reduce landfill waste – and a Naylor Love project on the North Shore was WMIF-funded.

“They were renovating a four-storey building on Auckland’s North Shore,” says Roberts. “The project included Naylor Love building a complete picture of waste and intensive separation of waste products for recycling and re-use.

“They trained labourers – the ones who collect the waste – and the company collated a huge amount of data. They also invited 100 other people from throughout the industry to see what they’d done with the project. That’s the kind of culture change we are talking about.”

It’s too late for those who’ve already had the invisible $31,000 bill tacked on to their new home cost, but Roberts is optimistic that scenario can be avoided in the future.

Got an idea for reducing construction waste? Auckland Council’s Waste Minimisation and Innovation Fund offers grants of up to $50,000. Applications open in October.

For more information and places to recycle and dispose of your construction waste responsibly go to the Auckland Council website.