On-site waste minimisation
Waste generated during construction and demolition can be minimised, re-used or recycled.
It's been estimated that up to half of the waste that goes into New Zealand landfills comes from construction and demolition. Many common building materials - wood, concrete, metal - can be re-used or recycled.
Whether you're carrying out a do-it-yourself project or hiring a contractor, there are several ways you can minimise waste on the building site.
Why minimise waste?
There are several reasons to minimise waste:
- Smart use and re-use and recycling may save you and your contractors money - for example, through reduced material waste which means less costs, through income received for salvaged building materials, or through savings from not having to buy additional materials.
- Recycling and re-use helps to slow the filling up of landfills, reduces the cost of mining raw materials, slows the depletion of resources, and provides work for local people.
- Waste minimisation helps reduce toxic runoff and site contamination that could have long-term effects on your property once building has finished.
At the design stage
Many of the decisions you make during the design stage of a project and your choice of construction system will influence the amount of waste produced during construction and over the entire life of the building.
When you're hiring a designer, tell them to consider waste minimisation and ask how this will be achieved.
One way of reducing waste is to renovate an existing building rather than building from scratch.
To minimise waste:
- design so your building's dimensions fit the size of pre-made materials (such as flooring or cladding sheets, which are often manufactured in sizes that are multiples of 600mm) - this minimises offcuts
- make the design flexible enough to allow changes in the way the home will be used (see Making your home adaptable) - this reduces the need for major alterations
- group wet areas together to reduce the amount of plumbing materials you need
- use simple methods - this makes the construction/finishing process easier, avoiding the likelihood of rework
- use prefabricated components such as pre-cut, pre-nailed framing and roof trusses - construction is faster and less waste is generated on-site.
To minimise waste:
- if possible, use materials that can be re-used, recycled or returned to the supplier if undamaged
- if possible, use recycled materials or materials with recycled content
- use materials that don't produce dusts or pollutants that can harm human health or the environment
- use materials that are durable (so they won't need to be replaced very often or at all during the life of the building); materials will at least have to meet the Building Code's durability requirements.
Think about responsible disposal options for materials that cannot be re-used or recycled.
See the Materials section for more.
When you're hiring a contractor
If you're hiring a builder or other contractors, include a clause in your contract requiring the contractor to minimise waste.
Choose a contractor who understands waste minimisation and is happy to use a waste management plan. The plan should specify the types of waste that will be produced and what will be done to ensure they are re-used, recycled, returned to the supplier or disposed of safely (see BRANZ's REBRI web pages)for information on waste management plans).
When you're discussing your wishes with prospective contractors, point out that waste minimisation should benefit them - through reduced landfill costs - as well as benefiting you.
Minimising waste during construction
To minimise waste on the building site:
- store materials carefully so they won't get damaged - if necessary, keep them covered
- keep the building site tidy - this reduces the risk of materials being damaged, as well as making the site safer and easier to work in
- have a central location for cutting and storing off-cuts - if you need a short piece of material there may be a bit right there
- have separate bins or piles for waste that can be recycled, re-used or returned to suppliers if not used (insulation, cladding and timber are examples)
- re-use formwork, scaffolding, crates and pallets
- order only as much of a material as you need, rather than adding extra for wastage
- ask suppliers to reduce packaging if possible.
These tips apply regardless of whether you're carrying out a small DIY project or having major building or renovation work carried out by professionals. Professionals can get more detailed information about waste minimisation during the construction process from REBRI.
Minimising waste during deconstruction/demolition
The term 'demolition' implies destruction of an existing building. 'Deconstruction' means taking a building apart carefully so that material can be salvaged for recycling or re-use.
Deconstruction reduces waste, which means lower landfill fees. You may be able to re-use or recycle salvaged material in your own building project, or sell it.
What can be recycled or re-used?
- Timber - for example from floors, skirting boards, framing, and weatherboards - can be salvaged for re-use in a building project or for other uses such as furniture. Some native timbers are hard to get from anywhere except demolition/deconstruction sites.
- Windows and doors, electrical and plumbing fixtures, and hardware such as door handles and locks can be salvaged for re-use.
- Concrete and concrete blocks can be crushed and used as aggregate and hardfill.
- Whole bricks can be salvaged for re-use. Broken bricks can be crushed for other uses such as landscape cover or fill.
- Metals can be recycled.
Tips for reducing waste during deconstruction
To reduce waste during deconstruction:
- make a plan before you start, identifying what types of waste will come from the deconstruction, and where you might be able to re-use, recycle or sell them
- schedule enough time for deconstruction
- dismantle buildings in the reverse order to construction
- separate the materials to reduce the cost and time of handling, and store material types separately.
- Store materials carefully to prevent damage.
Waste exchanges put people with waste to dispose of in touch with people who want to use it. They deal mainly with business or industrial waste. They are usually supported by local bodies and are a free service. The Waste Management Institute of NZ's website has a list of waste exchanges.
Safe disposal of waste
Some waste can't be re-used or recycled. You'll need to find ways of disposing of it safely and responsibly. It's best to consider this early on in the building project.
Sometimes, this waste can be hazardous to people, pets or the environment. Or it may be that no recycling options exist.
To minimise harm to the environment:
- don't tip paints, finishes or solvents down the drain, and don't wash brushes and tools over a drain - instead, contain any leftovers and dispose of it as solid waste
- in some locations polystryrene offfcuts and packaging can be recycled into underfloor insulation (donít burn them; if you do, toxic gases may be released)
- roofing and other metals may be be sold to a scrap metal merchant
- pick up discarded nails, glass, metal objects and offcuts so they don't end up in garden soil for children or pets to find.
Any materials used during a construction project should have safe disposal information provided on the pack, or by the supplier. Ask for Materials Safety Data Sheets, or get your builder to source them for you.
Information on disposal options including what is recyclable and what isn't can be obtained from your regional council, local or district council and the Ministry for the Environment.
Ask designers and contractors what the future maintenance requirements of the building are likely to be. Maintaining your home will extend its life, which will reduce the waste involved in removing and replacing parts of the building that have worn out. Carrying out specified maintenance is often required by product manufacturers' as part of a warranty.
From Smarter Homes
- Monitoring progress during construction; this has information about storing materials to prevent damage.
From other sites
BRANZís REBRI (Resource Efficiency in the Building and Related Industries) web pages have a lot of useful information, including:
- how to develop waste management plans
- easy guides to re-using and recycling different building materials
- contact details for recycling organisations
- a Resource Routing Calculator which allows you to compare the economic value of sending waste to landfill or to a reclamation facility, factoring in cost of transport and skip hire, value and weight/amount of material, amount of contaminant
The Ministry for the Environmentís website has a web page on questions and answers about construction waste.
The former Waitakere City Councilís website has a factsheet Avoiding Construction Waste (PDF 69 KB).
You can also find more information from the following sites:
Information about the Resource Management Act can be found at www.rma.govt.nz