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News: New Home Insulation

Building Code changes affecting new homes

What the new Building Code changes mean for existing and new homes.

The Ministry of Business, Innovation and Employment (MBIE) has introduced 6 new climate zones (see map on right) which now means new homes can be better designed and built based on the climate they're in.

The new Building Code changes are expected to reduce the energy to heat and cool new homes by 40%. The changes for residential insulation are as follows:

  • Ceiling insulation - increase of minimum value of R6.6 across all 6 new climate zones. This can be achieved by double layering ceiling products in trussed roofs and roofs with a cavity space. Mammoth already has a number of double layer options available that meet the new requirements.
  • Underfloor insulation - will have different R values across the country with the minimum required increasing from R1.3 to up to R1.7 for slab-on-ground and up to R3.0 for timber sub floors.
  • Wall insulation - there is almost no change to the current R2.0 that is currently called for.

See the table below for more details. (Courtesy of BRANZ).

H1table Zones

What does this mean for new build homes?

These building code changes impact significantly on new builds. We have products and solutions that can help you, or we can help your architect/ designer with our H1 Calculations to help ensure you comply with the new regulations.

What does this mean for existing homes?

The insulation requirements for existing homes remain unchanged.

Why the changes to the Building Code?

The desire for warmer, drier healthier homes is reflected in these changes, as the longer term energy costs savings and increased health benefits will be substantial. Higher insulation R values not only increases energy efficiency in building but also improves the health, comfort and wellbeing of the occupants. These changes are also likely to achieve cost savings to the health system because of reduced hospital admissions and GP visits.

When do the Building Code changes start?

The effective date of the new acceptable solutions and verification methods was 29th November 2021 with a transition period of one year ending 3rd of November 2022. You can read more about the Building Code changes on the MBIE site here.

How the Mammoth team can help

The Mammoth team already have solutions in place to meet the Building Code. Contact us today for more information.


Mammoth® Modern Insulation
Manufactured by InZone Industries Ltd
PO Box 204 289
Auckland 2161
New Zealand


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