Is Double Glazing mandatory in New Zealand homes?

Double glazing has been used for decades in many countries around the world due to its excellent insulating properties. Many homeowners in New Zealand are curious about whether double glazing is a legal requirement, or if it's simply a recommended upgrade.

In this blog post, we'll explore the regulations around double glazing in New Zealand and help you understand whether it's a legal requirement for existing homes, rental properties, and new builds.

New Builds

Whenever a home is built, it needs to meet insulation requirements from the current building code, which are specified in the ‘Building thermal envelope’ section. There are a number of things that need to be measured in order to calculate the thermal envelope of a building, including insulation in the floor, walls, windows, doors and roof. Insulation in these areas is measured using R-Values (thermal resistance rating), which measures the thermal resistance of a material. The higher the R-Value, the more thermal resistance the material has, resulting in better insulation.

These insulation requirements have been updated many times across various iterations of the building code, with minimum R-Value requirements in floors, walls, windows, doors and roofs increasing over time.

Since the mid-2000s, most kiwi homes have required at least standard double glazing in their windows and doors to meet the building thermal envelope requirements. In 2023, there has been further changes to the building code, significantly increasing the minimum insulation requirements. This means that most new homes require high-performance double-glazing units (Low E Glass and Argon Gas Fill) such as SureTemp LE, and thermally separated aluminium joinery such as SureFRAME, to meet the new standards.

Eversure specialises in installing double glazing into existing homes and doesn’t supply double glazing for new builds, however if you’re thinking about building a new home and are looking for advice, we’re happy to answer any questions.

Existing Homes

As noted at the beginning of the article, the insulation requirements of existing homes are essentially whatever the building code specified at the time the home was built. This is why most homes built prior to the mid-2000s have single glazed windows and doors, as the insulation standards were much lower and could be met without double glazing.

There is a scenario where the insulation requirements of an existing home can change, which is when renovations requiring consented work are carried out. Usually, to get consent, the renovated areas need to be brought in line with the current building code, meaning windows and doors would need to be double glazed. There can, however, be exceptions to this rule, so it’s important to fully understand the requirements and your obligations prior to undertaking a renovation that includes consented work.

If you are looking at retrofitting double glazing into your home, which is what Eversure specialises in, this can be done using either a retrofit method such as SureFIT, or by installing new joinery such as SureFRAME. When undertaking this kind of work, it’s a requirement that the installation method, thermal performance and safety requirements of the existing joinery needs to be either matched or improved upon with the new windows and doors. By installing high performance double glazing, you can significantly improve the thermal performance of your windows and doors, bringing them much closer to the current standards. The beauty of this kind of project, is that unless it is part of a larger renovation project or the frame sizes are increasing, you should not require consent.

Rental Properties

While rental properties have requirements around window safety, draughts and ventilation, double glazing of windows and doors for improved insulation is not currently mandatory. In 2019, New Zealand introduced the healthy homes standard for rentals which includes minimum standards for heating, insulation, ventilation, moisture ingress and drainage, and draught stopping, however double glazing is not currently part of this.

Despite it not currently being mandatory, many landlords find that double glazing is a smart choice for their rental property, as it can help them upgrade the window safety, reduce draughts and improve ventilation to meet the healthy homes standards. It will also improve the aesthetics, create a more comfortable environment for tenants and help to reduce condensation which can cause mould and rot. This will make the property more attractive for prospective tenants and reduce the likelihood of future expenses related to repairs of rotten timber or mould.

Conclusion

Double glazing has been mandatory in new builds for many years, with current standards now requiring installation of high performance glass (Low E and Argon Gas) and frames (thermally separated aluminium) in most new builds. While it is not currently mandatory in existing homes and rental properties (unless work requiring consent is being carried out), double glazing is a smart investment for any homeowner or landlord. Double glazing adds significant value by improving a home's energy efficiency, reducing noise pollution, improving safety, reducing condensation, improving functionality, reducing maintenance requirements and more.

If you are looking to get started, you can book in a consultation here. We understand that every home is unique with different needs when it comes to double glazing. With our consultation at your home, we can fully understand what you want to achieve from your project so we can develop a comprehensive bespoke quote for you.