Understanding Wall Insulation Requirements for Existing Homes

If you own an older home, there’s a good chance your walls aren’t insulated. Most homes built before the 1990s were constructed without insulation in the external walls. Even homes built later may have thin or patchy wall insulation that doesn’t meet today’s standards.

There’s currently no legal requirement for homeowners to upgrade wall insulation in existing homes unless they’re carrying out major renovations. However, insulating your walls can dramatically improve the warmth, comfort, and energy efficiency of your home. It also helps lower heating bills and reduce mould and dampness caused by cold surfaces.

If you’re a landlord, under the Healthy Homes Standards, you must meet minimum requirements for ceiling and underfloor insulation, but wall insulation isn’t compulsory. Still, adding wall insulation is one of the most effective ways to improve a home’s overall thermal performance and also keep your tenant warm and cosy.

Why CosyWall is Ideal for Insulating the Walls of Existing Homes

CosyWall is a high-performance wall insulation system designed for retrofitting into existing New Zealand homes. It uses dry glasswool fibre that is blown into the wall cavity through small holes, filling the void and creating a consistent thermal barrier.

Unlike some traditional insulation batt or segment style products, CosyWall fills every corner of the cavity, helping to achieve higher R-values and better thermal performance. The system is CodeMark certified, meaning it’s approved for use under the New Zealand Building Code and can be used with confidence by homeowners, landlords, and builders.

CosyWall is installed from the outside or inside of the home with minimal disruption. Once the insulation is in, the small access holes are sealed and the surface is repaired. The result is a warmer, drier home that stays comfortable all year round.

Wall Insulation Requirements for New Homes, And Why They Still Matter for Older Homes

When building a new home in New Zealand, external wall insulation must meet the total R-value of R2.0, as required by the Building Code. This applies across all climate zones and is designed to ensure modern homes are warmer, drier, and more energy efficient.

While these standards don’t apply to existing homes unless major renovations are being done, we recommend aiming to match or exceed the R2.0 standard when insulating your existing walls. Meeting modern wall insulation requirements is one of the best ways to improve the comfort and efficiency of your older home, even if it’s not a legal requirement.

Ready to Improve Your Home’s Comfort?

If your home feels cold in winter or heats up quickly in summer, insulating your walls with CosyWall can make a noticeable difference. Learn more about how the system works and book an assessment at www.wallinsulation.co.nz. We also have created an wall insulation calculator to provide an estimate on the cost of insulating your walls. Try the calculator out for yourself now!