Installing wall insulation

Wall insulation makes a big difference to the comfort and warmth of your home. If you are planning renovations, it's a great time to consider wall insulation.

Watch: How to install wall insulation | 3:30 mins

Installation checklist

Check local building consent requirements

Retrofitting wall insulation needs a building consent unless your local council grants you a?discretionary exemption. Either way, it must comply with the Building Code. Find out about requirements through your local council.

Council maps and websites - LGNZ website

Ensure your wall cavities are dry

Leaks or moisture issues in wall cavities can be worsened by installing insulation, leading to timber decay and toxic mould growth. To make sure that the outside cladding and flashings are in good condition, and there are no hidden plumbing leaks, consult a qualified builder (who is a licensed building practitioner) or a registered or accredited building surveyor.

Registered building surveyors - New Zealand Institute of Building Surveyors website

Accredited building surveyors - Building Officials of New Zealand website

Check the building paper in your walls

Building paper (wall underlay) prevents insulation from coming into contact with the outer cladding of your house, reducing the risk of moisture problems that can lead to timber decay and toxic mould growth. Building surveyors can check whether the building paper in your walls is intact. If not you can retrofit it, provided your wall is dry - refer to the NZS 4246:2016 insulation installation standard (see link below).

Get your electrical wiring checked

If you have existing electrical wiring inside your external walls, we recommend a safety inspection by a registered electrician. They can check whether your wiring is in safe condition and adequately rated so it doesn’t overheat when surrounded by insulation. Rewiring or circuit breakers may be required if your house has unsafe wiring.

Get the insulation installed to the New Zealand Standard

We recommend using a trained professional to install your wall insulation. Look for an installer who:

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

New Zealand Standard NZS 4246:2016 contains everything you need to know about installing insulation. It's easy to follow with lots of colour pictures, and it's free to download (see link below).

?New Zealand Standard for installing insulation