Insulation
Around 900,000 New Zealand homes have substandard insulation. [1] Good quality, well installed insulation can significantly reduce the rate of heat loss in your home. This makes your house easier and cheaper to heat properly than without insulation.
On this page:
Benefits of insulation in your home
Good insulation means a significant reduction in the rate of heat loss in your house via ceilings, walls, floors, windows and doors. This reduced rate of heat loss makes the house easier and cheaper to heat properly. This means the house will be healthier and more comfortable to live in.
Heat loss in the home
Heat is lost from the inside of the house in two main ways:
- Air infiltration - hot air escapes from the house through cracks, gaps, holes, open chimneys etc. This is replaced by cold air.
- Conductivity - hot air escapes directly through the elements of the house such as walls, ceilings, floors, windows, skylights and doors.
If your house is draughty, any insulation you install won't be able to do its job properly. It's important to minimise the amount of air leakage from your house at the same time as you improve the insulation.
Heat always finds the easiest path out of a house. If you insulate one part of your house, the ceiling for example, you reduce the rate at which heat is lost through the ceiling. But the rate at which it escapes through other parts of the house increases. To get best results you need increase the insulation for all of the outside building elements of your house.
What to insulate?
The following is the sensible order in which to install insulation:
- Insulate your ceiling first. Heat rises. In an uninsulated house the majority of heat is lost through the ceiling
- Next, insulate under your floor. If the floor is cold, you feel cold.
- Walls and windows are both relatively difficult and expensive to insulate in an existing house. These are jobs normally left for when individual rooms or a whole house is being renovated. If you need to remove wall lining in your house, you can install wall insulation.
- Similarly install double glazing when replacing windows.
How much insulation?
The amount of insulation you need depends on how cold it gets where you live. The table below gives recommended minimum insulation levels (or R-values) for existing homes - it's good to install more if you can.
| MINIMUM RECOMMENDED R-VALUES FOR EXISTING HOMES | ||
| North Island (excluding Central Plateau) | South Island and Central Plateau | |
|
Ceilings with 0-75mm of existing insulation |
R2.8 blanket or R3.4 segment insulation |
R3.2 blanket or R4.0 segment insulation |
|
Ceilings with 75-120mm of existing insulation |
R1.8 blanket insulation | R2.4 blanket insulation |
| Underfloor | R1.4 bulk insulation | R1.4 bulk insulation |
| Walls |
Check the thickness of your wall cavity and find the highest R-value product at that thickness |
|
For more information on R-values, see the effective insulation page.
Types of insulation products
A variety of insulation products are available on the market. It's important to understand which types of product are best suited for different applications.
More information about this is given on the page about each area that is being insulated.
Download the list of specific insulation products accepted for use under the Warm Up New Zealand: Heat Smart programme.
Take action
Find out if you are eligible for ENERGYWISETM insulation funding.
More information
• For comprehensive information on insulation, download the Department of Building and Housing booklet: Your Guide To Smarter Insulation.
• For a comprehensive discussion on insulation see the Smarter Homes website
Notes:
[1]Clark, S.J., Jones, M. & Page, I.C. 2005. New Zealand 2005 House Condition Survey. Wellington: BRANZ
