Ceiling insulation
Research indicates that around 375,000 New Zealand homes have inadequate ceiling insulation.[1] Good ceiling insulation is first thing to consider in most houses. Whether it's blanket or segment insulation, this needs to be well installed and thick enough for your situation.
On this page:
- How much insulation?
- Which insulation material?
- Blanket insulation or segments?
- Take action in your ceiling
- Installing ceiling insulation
How much insulation?
| 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 |
If your house is multi-story, you only need to insulate the main upper ceiling. It isn't necessary to insulate the ceiling between floors - it's more important to insulate the outer envelope of your house. You may, however, want to insulate ceilings between floors if the ground floor is a separate flat. This can also be done with sound proofing insulation to control noise.
Which insulation material?
Ceiling insulation can be made from polyester, wool, fibreglass and a range of other materials. Not all insulation is created equal though, and some products do have definite drawbacks.
If you are comparing different types of insulation, remember to check:
- what sort of performance guarantees the insulation manufacturers offer on their products
- that the insulation you are looking at has been tested to the AS/NZS 4859.1 Standard - look for a AS/NZS 4859.1 compliance statement on the insulation packaging
- what's involved in safely installing the insulation if you are thinking of doing it yourself.
Once you know these things, make sure you are comparing products with similar R-values.
Blanket insulation or segments?
Insulation is available as either:
- Segments, which fit between the joists above your ceiling, or
- Blankets, designed to be rolled out across the top of the ceiling and the joists.
If you use segments, you need to put in higher R-value insulation to make up for the heat that gets lost through the timber joists. Modelling suggests that in order to achieve R2.9 or R3.3 with well installed segment insulation you need to use R3.4 or R4.0 products respectively.
Blanket insulation that covers ceiling joists prevents extra heat loss through the timber joists. This allows slightly lower R-value products to be used. To achieve R2.9 or R3.3 in ceilings with well installed blanket insulation you need to use R2.8 or R3.2 products respectively.
Take action in your ceiling
The easiest way to check if you need ceiling insulation is to have a quick look in your roof space. Find out more about checking if your ceiling insulation is adequate.
You may be eligible for ENERGYWISETM funding to get insulation installed in your home.
Installing ceiling insulation
It is easiest to install insulation with two to three people. Although it is possible to do it by yourself, it will be harder to get the quality of installation that you need for your insulation to work as well as possible.
Access to your roof space is normally through a manhole in the ceiling. If you are unsure of how to access and safely work in a roof space, EECA suggests that you get your insulation professionally installed.
Standards New Zealand has published a standard on installing insulation. It covers a variety of products and provides detailed instructions on how they should be installed.
Download Standard NZS 4246:2006 Energy efficiency - Installing insulation in residential buildings.
For more tips see the Installing Insulation page.
Safe installation around downlights, chimneys and flues
Downlights, chimneys, flues and extractor fans can produce a lot of heat, so special care needs to be taken with them to ensure safe insulation installation. EECA recommends having your insulation installed by a professional, but there are some things to consider if you are doing it yourself or want to check your insulation is installed correctly.
If you have recessed downlights and insulation, you should check your ceiling insulation occaisionally to be sure it hasn't slumped towards your downlights creating a fire hazard.
For more information on safe installation of insulation around downlights, chimneys, flues and extractor fans refer to the Installing Insulation section.
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 choosing insulation products, see the Smarter Homes website.
Apply for an insulation grant
Grants are available for ceiling and underfloor insulation, regardless of your income, if your house was built before 2000. Find out more about home insulation funding.
Seek professional advice
- Consult a builder or visit a hardware shop that sells insulation products
- Use our suppliers and partners directory
- Get a professional report of your home's insulation requirements with a Home Energy Rating.
Notes:
[1] Clark, S.J., Jones, M. & Page, I.C. 2005. New Zealand 2005 House Condition Survey. Wellington: BRANZ
