Heating & Energy

Product overview

Welcome to New Zealand's trusted, independent source of practical information. We provide recommendations on products and trusted businesses, exclusive deals and consumer advice. 

Insulation

12mar insulation hero default

We explain your home insulation options.

Insulation makes your home easier and cheaper to heat. Warm indoor temperatures, along with adequate ventilation, make for a drier and healthier place to live. We discuss insulation options for new and existing homes, explain changes to the building code that affect insulation requirements, and tell you where to get more information.

On this page

Compare products

Insulation basics

We look at why you need insulation, how it works and explain 'R values'.

Want to be snug and warm this winter? Upgrade to a Gold or Silver membership to view our advice.

Building Code requirements

By law, since 1978 all new homes and major renovations in New Zealand have had to be thermally insulated.

Since November 2007 the standards of insulation required for new homes and major renovations have been markedly increased. The minimum requirements for energy efficiency in house design and construction are spelled out in the Building Code's energy effectiveness clause H1. The standard AS/NZS4859.1 sets the testing and labelling requirements for insulation materials used in the home and whether they comply with the requirements of H1.

The new requirements

The new minimum insulation requirements, including double glazing, were introduced in stages around the country.

The tables below show an example of the new overall R values for wall, roof, floor and glazing required in different parts of the country for non-solid (timber-framed) construction houses.

Full details of insulation requirements can be obtained from the compliance documents of the Building Code.

Zones 1 & 2 - North Island excluding the Central Plateau Roof Walls Floor Vertical glazing Skylights
Building Code NZS 4218:2004 R2.9 R1.9 R1.3 R0.26 R0.26

Zone 3 - South Island and the North Island Central Plateau Roof Walls Floor Vertical glazing Skylights
Building Code NZS 4218:2004 R3.3 R2.0 R1.3 R0.26 R0.31

To achieve the required R2.0 for the walls of a Zone 3 timber house, for example, you need to install an insulation product with an R value between 2.2 and 2.8. This is because the higher R value for the insulation product offsets the lower R value of the timber framing (see "Insulation basics").

There are different R requirements for solid construction houses. Details can be found in Clause H1 of the Building Code.

Before you get started

Seal around doors and windows.
Seal around doors and windows.

Before spending money on insulation, sort out draughts.

Seal around doors and windows, block off unused chimneys and remove downlights that are not rated 'close abutted' (downlights with air gaps around them).

But remember you will still need to air or ventilate the house to prevent damp accumulating and to maintain air quality. Even on the coldest nights you will need some fresh air in the house. There is a fine line between draughts and ventilation.

You may be eligible for help (see below) to fund insulation improvements.

Need some expert advice?

If you are unsure about how best to insulate your house, consider paying for a home energy rating. For background information see www.energywise.govt.nz.

You will receive an independent assessment of the energy performance of your home including how well the building's design, construction and orientation enables it to maintain a comfortable indoor temperature, and how efficient the indoor heating and water heating are. You will get recommendations for the most cost-effective ways to improve the house's energy efficiency and reduce your energy costs.

Free insulation

Warm Up New Zealand: Healthy Homes projects provide free ceiling and underfloor insulation for low-income households occupied by people with health needs related to cold, damp housing. Availability is through regional projects.

Home owners or tenants may be eligible if they have a Community Services Card and the house is occupied by someone under 17 years or over 65 years. People can also be referred to the programme by a health provider if they are at risk from illness linked to cold, damp housing - such as a respiratory condition.

Visit www.energywise.govt.nz for terms and conditions and more information.

Are you going to install insulation yourself?

Here are some things to consider before you buy and install insulation.

  • The first step is to check your current insulation: is there any? What state is it in?
  • Check what the R values are for your climate zone (see 'Building Code requirements' above).
  • Make sure all leaks (roof and pipes) are repaired so the new insulation doesn't get wet. Damp insulation is less effective.
  • Have an electrician check you can safely cover electrical wiring that can't be placed outside the insulation.
  • If you have recessed downlights that are not closed abutted (CA) rated, replace them to eliminate the air gaps. CA rated recessed light fittings are now available that allow insulation to touch them. If you're not replacing the downlights, check to see how big a gap in the insulation is needed around each light fitting to prevent over-heating.
  • Choose a product that is independently accredited and complies with the standard AS/NZS 4859.1: 2002. Compliance with this standard is mandatory under the Building Code. A compliance statement must be on the label of the insulation.
  • Wear a dustmask, goggles, gloves, long sleeved shirt and closed footwear when installing fibre insulation products.

The quality of installation is of paramount importance. Even small gaps will undermine the performance of the insulation. A comprehensive easy-to-use guide on installing insulation is available as a free download from www.energywise.govt.nz.

Insulating existing homes

Many houses built before the 1978 regulations took effect have no insulation. Even post-1978 houses may lack sufficient insulation. We look at how to insulate the roof space, walls, floors and windows.

You need to be a Gold or Silver member to view this content.

Insulating new houses

Minimum insulation requirements for new homes are now mandatory.

If you're building a new home, we recommend insulating beyond the code's minimum requirements.

You need to be a Gold or Silver member to view this content.

Materials

There are a variety of materials that can be used to insulate your home. We look at the pros and cons of a selection.

You need to be a Gold or Silver member to view this content.

Our advice

When looking at insulation for your home, consider these points.

You need to be a Gold or Silver member to view this content.

×