NZBC Insulation Requirements

NZ Building Code insulation requirements (H1)

The insulation rules for new homes and buildings sit under clause H1, Energy Efficiency, of the New Zealand Building Code. MBIE issued the 6th edition of H1/AS1 on 27 November 2025. The previous 5th edition can be used until 26 November 2026; from 27 November 2026 only the new rules apply.

What changed

The schedule method is gone. There is no longer a simple table of minimum R-values to tick off. Designers show compliance with the calculation or modelling method.
Timber framing counts for more. Walls must be calculated assuming at least 38% of the wall area is framing, unless a lower figure can be shown. Timber conducts heat much faster than insulation, so this lowers the real R-value of most framed walls.
Areas are measured from the inside. Roof, wall and floor areas now use overall internal dimensions.
Slab-on-ground floors no longer have their own minimum R-value in the calculation method, but slab heat loss still counts in the total.
The overall level of insulation required is unchanged. MBIE says the changes are about flexibility, not lowering the bar.

Where Eurothane GP PIR fits

Eurothane GP has a thermal conductivity of 0.022 W/m·K. That gives R4.05 in a 90mm board, compared with R2.8 for the best 90mm glass wool wall batt. The boards can go between the framing, over it, or both.

Under the new rules, a continuous layer of PIR fixed over the framing is one of the most effective ways to lift a wall's construction R-value. It covers the studs, plates and nogs that the 38% framing rule now counts. See our installation drawings for roof, wall and floor details, and the product page for R-values by thickness.

Climate zones

New Zealand's six H1 climate zones, from zone 1 in the Far North to zone 6 in Central Otago. Your zone sets the reference building your design is measured against.

Good to know

H1/AS1 covers housing and buildings up to 300 m². Larger buildings use H1/AS2.
Your designer or architect is responsible for showing compliance, and your council checks it at consent.
Eurothane GP is supplied with a declaration of performance and fire test reports; see Certificates.

This page is a guide only. For the full requirements, see MBIE's H1 Energy Efficiency page.

Specifying PIR for a project? Call us on 03 540 3003 or send us your plans. We supply nationwide, with freight quoted on each order.