Installing ceiling insulation

Ceiling insulation is the easiest, cheapest and most effective insulation to install in your home.

Using a qualified professional

If you aren't getting your insulation done under the Warm Up New Zealand: Healthy Homes programme, we recommend using a trained professional installer who: 

  • works to the New Zealand insulation installation Standard NZS 4246:2016.
  • has completed the insulation installer training of the Insulation Association of New Zealand (IAONZ).

 New Zealand Standard for installing insulation

List of trained installers - IAONZ website

 Warm Up New Zealand: Healthy Homes programme

DIY checklist

If you’re going to install ceiling insulation yourself then there are some things you should think about.

  • Safety - as with all DIY projects, there are safety considerations. Make sure you read and follow the Health and Safety advice in Appendix B of New Zealand Standard NZS 4246:2016. If you're not sure, get a professional to install the insulation for you.
  • Ceiling space - does your house have a ceiling space? If not, it could be tricky to install, but it may still be possible to put insulation in your skillion roof or cathedral ceiling.
  • Existing insulation - a quick look in your roof space will tell you if you have any insulation already. If there is, you'll still want to check what state it's in.
  • Leaks and electrical issues - check your roof and any plumbing in the roof space for leaks. Check that your electrical wiring and installations are in safe condition. You should fix any issues before insulating.
  • Multi-story homes - only the upper ceiling between your home and the outside needs to be insulated. You don't need to insulate the ceiling between floors except above or below unheated rooms like laundries, workshops or garages.

 New Zealand Standard for installing insulation

 Checking for existing ceiling insulation

How much ceiling insulation?

How much insulation you need in your ceiling depends on how cold it gets in your area and on the thickness and condition of any existing ceiling insulation. The R-value is a measurement of the insulation's effectiveness - the higher the R-value, the more effective it is at preventing heat loss.

If you are building a new home your insulation must meet the building code.

Building Code - Building Performance website

Minimum recommended R-values for existing homes

The table below lists recommended minimum R-values for retrofitting ceiling insulation into existing homes. We recommend going higher if you can.

Minimum recommended R-Values for existing homesNorth Island (excluding Central Plateau)South Island and Central Plateau
Ceilings with no insulation, or up to 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