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 a grant or interest subsidy (see below) to fund insulation improvements.

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).
  • 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. See our downlights report for more information.
  • 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

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.

Funding available


The Energy Efficiency Conservation Authority (EECA) offers funding for improvements to insulation for homes built before 2000, through its Warm Up New Zealand: Heat Smart programme.

Funding for insulation  
All eligible houses 33% of the total cost up to $1300 (including GST)
Homeowners who hold Community Services Cards 60% of the total cost, or more than 60% if you qualify for a special project.
Landlords with tenants who hold Community Services Cards 60% of the total cost

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

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