Insulation requirements for NZ installers: H1, Healthy Homes and the rules between them

Which rule-set applies to this job?

Start every job with one question: is this new or consented building work, or is it an existing home? On new builds and consented alterations, the insulation is part of the building consent and must meet Building Code clause H1 Energy Efficiency, so the R-values on the consented plans or the designer’s H1 calculation are what you install. On an existing rental that is being brought up to standard, the target is the Healthy Homes insulation standard, which is a lower and simpler bar than current H1 and uses a different climate map. The practical rule is never to quote a rental retrofit using new-build R-values (you will price yourself out), and never to install a consented job to the lower rental figures (the inspector will fail it).

H1 on consented work: the 6th edition

The current Acceptable Solution is H1/AS1 6th edition, in force from 27 November 2025. Its biggest change for installers is that the schedule method, the simple table of minimum R-values by climate zone and building element, has been removed, so compliance goes through the calculation method or modelling, and the calculated build-up of the wall (including the framing) matters. The 6th edition also does not include foil insulation. The 5th edition, as amended, can still be used to show compliance until 26 November 2026, and MBIE has said that from 27 November 2026 anyone using H1/AS1 in a building consent application must use the 6th edition. If you are quoting a consented job today, the safe approach is to install what the consented plans say, not what a table from an older job says. Record the product, the installed R-value and the area for each element (ceiling, walls, floor) so the builder can give the council evidence of H1 compliance at code compliance certificate stage. Our H1 6th edition explainer covers the change in plain English.

Healthy Homes insulation standard for rentals

For rentals that were consented before 3 November 2022, the Tenancy Services standard sets minimums by NZS 4218 climate zone (a three-zone map, not the six H1 zones). Ceiling insulation must be at least R2.9 in zones 1 and 2 and R3.3 in zone 3, and underfloor insulation must be at least R1.3. Existing ceiling insulation installed before 1 July 2016 must be at least 120 mm thick; thinner insulation is acceptable only if the landlord can show it met the minimum R-value when installed and has not degraded by more than 30%. Insulation has to be in reasonable condition with no mould, dampness, damage or gaps, and installed in line with NZS 4246:2016. There are exemptions: where access is impracticable or unsafe, where the original underfloor insulation is still in reasonable condition and the landlord holds compliance documents, where there is another habitable space directly above or below, and for low-pitched roofs or small ceiling cavities that need other building elements insulated instead. Landlords who breach their healthy homes obligations can face penalties of up to $7,200. A completion record that lists product, R-value, thickness and zone is the evidence a landlord needs, so write it for them. Our Healthy Homes calculator works through the zone and minimums.

• Ceiling: R2.9 (NZS 4218 zones 1–2) or R3.3 (zone 3).
• Underfloor: R1.3.
• Pre-July-2016 ceiling insulation: at least 120 mm thick, unless it can be shown to have met the R-value and degraded by 30% or less.
• Condition: no mould, dampness, damage or gaps; installed to NZS 4246:2016.

Underfloor foil: removal, never repair

Foil underfloor insulation has caused electrocutions in New Zealand, because staples or nails can pierce a live cable. Since 1 July 2016 a ban issued under the Building Act prohibits installing foil insulation in residential buildings that already have an electrical installation, and prohibits repairing existing foil. If you find ripped or sagging foil, you cannot staple it back up. It has to come out and be replaced with a non-foil product. Treat any existing foil as potentially live: isolate the power at the switchboard before anyone goes under the house, and do not leave an installer to find out the hard way. Some rental guidance accepts existing foil that is in reasonable condition and meets the R-value requirement, but that is a question about leaving it alone, not about touching it. If you are removing foil, say so on the quote and the job card.

Consent traps: walls and firewalls

Schedule 1 of the Building Act 2004 exempts installing thermal insulation in an existing building from building consent, with two exceptions: insulation in an external wall and insulation in an internal fire-separation wall. Retrofitting either needs a consent. That catches wall-cavity fill and wall-lining retrofits, and it is the line between a ceiling or underfloor job you can start on Monday and a wall job that needs paperwork first. A separate exemption covers installing a ground moisture barrier in the subfloor of an existing building. The Healthy Homes moisture standard also requires a rental with an enclosed subfloor to have a ground moisture barrier where it is reasonably practicable, so on rental underfloor jobs decide whether one is needed and quote it deliberately rather than leaving it out.

Asbestos in pre-2000 homes, and keeping the records

Older ceilings, linings and soffits can contain asbestos, and insulation work disturbs them: lifting ceiling tiles, drilling through linings, working in a roof space above a textured ceiling. Under the Health and Safety at Work (Asbestos) Regulations 2016, asbestos at a workplace has to be identified, and a structure built before 1 January 2000 should be inspected by a competent person before refurbishment work starts. Make that check, and its result, part of the pre-start routine on every older home. For the rest of the paperwork, Toolie’s insulation pack separates the two rule-sets in the same way as this guide. It checks an existing rental ceiling against the NZS 4218 zone minimum and the 120 mm rule, checks underfloor against R1.3, warns when existing underfloor foil is recorded, and flags that external-wall or firewall retrofits need a consent. The insulation statement it produces records product, R-value and zone for the landlord or builder. See Toolie for insulation installers for the quoting side.

Sources

Official sources this guide relies on. Rules change, so check the current version before relying on a date or threshold.

• Tenancy Services: Healthy homes insulation standard
• MBIE: H1/AS1 6th edition
• MBIE: Foil insulation ban
• Building Act 2004, Schedule 1 (exempt building work)
• Health and Safety at Work (Asbestos) Regulations 2016

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