Construction and demolition waste sent to New Zealand landfills totalled approximately 5.25 million tonnes in 2023, representing around 69 percent of all landfilled waste, according to the Ministry for the Environment’s construction and demolition waste baseline. That figure is higher than previous estimates, which had put the sector’s share closer to 40 to 50 percent.
The more useful number for anyone commissioning construction work is this: studies have found more than 75 percent of construction and demolition waste could be diverted from landfill, and some commercial projects achieve 90 percent. The gap between what is diverted and what could be diverted is not a technical problem. It is a process and procurement problem.
What the waste actually is
Three material streams dominate. Timber, plasterboard and concrete together make up around 80 percent of site waste. Add metals, floor coverings, packaging and general mixed waste and you have almost the entire picture.
The significance of the big three is that all of them have established diversion routes in New Zealand:
| Material | Diversion route |
|---|---|
| Timber | Biofuel, animal bedding, mulch, remanufacture |
| Plasterboard | Processed into fertiliser and soil conditioner |
| Concrete and masonry | Crushed for hardfill and aggregate |
| Metals | Recycled through established scrap markets |
| Cardboard and packaging | Recycled |
| Carpet and soft flooring | Limited but developing options |
Contamination is what breaks these routes. Clean, separated plasterboard has a market. Plasterboard mixed with timber, packaging and general rubbish in a single skip does not, and the whole load goes to landfill.
Where fitout sits in the picture
Fitout and refurbishment generate a disproportionate share of the problem relative to their construction value. New build creates waste through offcuts and packaging. Fitout creates waste through strip out, which means removing entire building elements that are still functional.
The New Zealand Green Building Council puts the average commercial fitout at 368.6 tonnes of waste, and attributes 32 percent of a commercial office building’s lifecycle emissions to fitouts. Because interiors turn over on lease cycles of five to ten years while the building stands for sixty or more, the fitout waste event repeats many times across a single asset’s life.
In Auckland specifically, construction and demolition waste accounts for around 40 percent of landfilled waste, running to roughly 570,000 tonnes in 2019.
How diversion actually gets achieved
Diversion is decided long before the skip arrives. The projects achieving 80 and 90 percent do a small number of things consistently.
Separate at source. This is the single largest determinant of outcome. Separate bins for timber, plasterboard, metals and clean fill, positioned where the work is happening rather than at the far end of the site. One mixed skip is the difference between an 80 percent diversion rate and a 20 percent one.
Write it into the contract. A waste management plan with target diversion rates, required reporting and evidence of disposal destinations. If diversion is not specified and measured it does not happen, because landfill is the path of least resistance for a subcontractor working to a programme.
Measure and report. Weighbridge dockets by stream, not a single total. What gets measured gets managed, and the data is also what supports Green Star credits and client sustainability reporting.
Deconstruct rather than demolish where the value justifies it. Careful removal of joinery, doors, glazed systems, light fittings and ceiling tiles preserves resale or reuse value. It takes longer than demolition, so it needs to be planned and priced deliberately rather than expected for free.
Design out the waste. Standard sheet dimensions, modular layouts and offsite manufacture reduce the waste generated in the first place. This is more effective than any downstream diversion effort, because waste avoided costs nothing to dispose of.
The offsite manufacturing effect
Waste behaves differently in a factory than on a site.
Software driven cutting optimises material yield across a whole production run rather than sheet by sheet. Offcuts are captured clean and sorted at the machine rather than swept into a mixed pile. Production is batched so that material is ordered to actual requirement. Packaging is controlled and returnable. And because the environment is consistent, diversion streams can be established as permanent infrastructure rather than reset on every new site.
Complete Construction’s robotic batch one facility in Auckland operates on these principles. Advanced CNC and robotic systems maximise material yield, and waste is separated at source and directed to established streams: timber to biofuel, gypsum to fertiliser, metals to recycling.
What clients should ask for
If waste diversion matters to your organisation, the following belong in the tender documents rather than in a conversation after award:
- A required minimum diversion rate, stated as a percentage
- A waste management plan submitted with the tender, not after
- Separate reporting by material stream with weighbridge evidence
- Named disposal and processing destinations
- A deconstruction assessment for any strip out, identifying what can be reused or resold
- Design for disassembly requirements in the design brief, so the next strip out is easier than this one
Ask contractors what their own facility achieves, not just what they promise on your project. A contractor whose manufacturing operation already runs separated waste streams has demonstrated the systems and supplier relationships exist. A contractor who has never measured it is making a commitment they have no track record of delivering.
The regulatory direction
The Ministry for the Environment’s construction and demolition waste baseline exists because the sector is a policy priority. MBIE’s Building for Climate Change programme includes a Whole of Life Embodied Carbon Emissions Reduction Framework, which introduces reporting requirements first and phased caps subsequently.
The practical implication is that measurement is becoming mandatory before reduction becomes mandatory. Organisations that already measure their waste and carbon by stream will find the transition straightforward. Those that do not will be starting from zero on a compliance deadline.
Frequently asked questions
How much construction waste goes to landfill in New Zealand? The Ministry for the Environment’s construction and demolition waste baseline puts approximately 5.25 million tonnes going to landfill in 2023, representing around 69 percent of all landfilled waste. In Auckland, construction and demolition waste makes up around 40 percent of landfilled waste.
What percentage of construction waste can be diverted? Studies have found more than 75 percent could be diverted, and some commercial projects achieve 90 percent. The three dominant materials, timber, plasterboard and concrete, account for around 80 percent of site waste and all have established diversion routes in New Zealand.
What happens to plasterboard waste in New Zealand? Clean, separated plasterboard is processed into fertiliser and soil conditioner. Contaminated or mixed plasterboard generally cannot be processed and goes to landfill, which is why source separation is the single largest factor in diversion outcomes.
How do I get a high diversion rate on my project? Specify a target diversion rate in the contract, require a waste management plan with the tender, provide separate bins at the work face rather than a single mixed skip, require reporting by material stream with weighbridge evidence, and design out waste through standard dimensions and offsite manufacture.
Does offsite manufacturing reduce construction waste? Substantially. Factory production optimises material yield through software driven cutting across whole production runs, captures offcuts clean at the machine rather than mixed in a skip, and allows permanent diversion infrastructure rather than streams reset on each new site.
Related reading
- The Hidden Carbon Cost of Fitout Churn
- Green Star and NABERSNZ: Which Sustainability Credentials Actually Matter
- Long Lead Items in New Zealand Fitout: What to Order First
Sources
- Ministry for the Environment, Construction and Demolition Waste Baseline, 2023
- Auckland Council, waste assessment data
- New Zealand Green Building Council, Green Star Fitouts, fitout waste and lifecycle emissions data
- BRANZ and WasteMINZ, construction and demolition waste research
- Ministry of Business, Innovation and Employment, Building for Climate Change programme
- Complete Construction environmental statement
This article is general information. Waste volumes and diversion rates vary by project and region.