A plain-English intro to H1 — the Building Code clause covering roof insulation and R-values, why it matters at re-roof time, and where to confirm current rules.
H1 is the Building Code clause covering energy efficiency, including insulation — and for roofs and ceilings it sets minimum thermal performance, expressed as R-values, that varies by climate zone. It matters most at re-roof and renovation time, when insulation can be improved and compliance obligations may apply.
The important caveat up front: the specific R-value requirements have been updated in recent years and can vary, so this article is a plain-English introduction to what H1 is, not a source of current compliance figures — for those, current guidance is the authority.
This is general information, not current compliance data or professional advice. For current figures and how they apply to your work, check with Auckland Council, a building professional, or MBIE.
What are the H1 insulation requirements for roofs?
Direct answer, in plain English: H1 is the Building Code's energy-efficiency clause, and for roofs and ceilings it sets minimum insulation performance (R-values) that varies by climate zone. The idea is that buildings should retain heat efficiently, and roof/ceiling insulation is a major part of that (a lot of a home's heat loss is through the roof), so H1 sets minimum thermal-resistance levels insulation must meet. The figures depend on where in NZ the building is — colder zones generally requiring more.
And they apply to relevant new work. The crucial point is that the specific required R-values have changed over recent years (with notable updates increasing requirements), so the current figures should always be confirmed with current guidance rather than assumed from any article. The insulation types and cost our guides cover are the practical side; H1 is the regulatory framework. This article explains what H1 is; MBIE, the council, and building professionals are the authorities on current requirements.
In short
H1 is the Building Code clause covering insulation, setting minimum roof/ceiling R-values that vary by NZ climate zone. It matters at re-roof and renovation time. The specific figures have been updated in recent years and can vary, so confirm current requirements with Auckland Council, a building professional, or MBIE. This is a plain-English intro, not current compliance data.
R-values and climate zones — the basics
Two concepts make H1 understandable: R-values — an R-value measures thermal resistance, how well insulation resists heat flow, with a higher R-value meaning better performance; H1 sets minimum R-values for roof/ceiling insulation (among other building elements), so meeting H1 means the insulation achieves at least the required R-value, the R-value basics our guide covers; and climate zones.
NZ is divided into climate zones, and H1's minimum insulation levels vary between them, with colder regions generally requiring more insulation than warmer ones, so the same clause produces different required figures in different parts of the country (Auckland sitting in its own zone with its own figures). Together they mean H1 compliance for a roof is "achieve at least the minimum R-value for this climate zone" — a figure that depends on location and that has been revised over time.
Because the figures change, the practical approach is to treat the framework as stable (H1 governs roof insulation via R-values and zones) while confirming the actual numbers from current sources, since an out-of-date figure is worse than none. For Auckland work, the council and building professionals can confirm the current zone requirements.
Why H1 matters at re-roof time — and the rules-change caution
H1 becomes practically relevant at re-roof and renovation time for two reasons: compliance may apply — depending on the scope of work and current rules, significant re-roofing or renovation work may bring H1 obligations into play, so whether it applies to a particular re-roof should be confirmed with Auckland Council or a building professional (this depends on specifics and current rules, not a blanket yes or no); and the practical opportunity.
Even where not strictly required, re-roofing is the natural moment to improve insulation, since the roof space is accessible and the work is happening anyway, so upgrading to current (or better) R-values during a re-roof is often sensible regardless of the strict obligation, the energy-saving and comfort benefit our energy guides describe, with new-build and major-renovation work connecting to the building expertise at our parent brand My Homes Construct.
Running through both is the rules-change caution: H1 requirements have been updated in recent years and can change again, so what is current now may differ later — making current guidance (MBIE, the council, building professionals) the reliable source rather than any fixed article. The honest framing: H1 governs roof insulation, it matters at re-roof time, the figures vary by zone and change over time, and current professional or council guidance is the authority for any specific project.
Practical takeaways
H1 sets minimum roof/ceiling insulation (R-values) that vary by climate zone, and it matters most at re-roof and renovation time. Because the required figures have been updated recently and can change, confirm current requirements with Auckland Council, a building professional, or MBIE rather than relying on fixed figures. Re-roofing is a good practical opportunity to improve insulation regardless. This article is a general introduction only — not current compliance data, and not a substitute for professional or council advice on your specific work.
Talk to us about re-roofing and insulation in Auckland
My Homes Roofing Expert re-roofs across Auckland and can coordinate insulation improvements at re-roof time, pointing you to current H1 guidance and building professionals for compliance specifics. Call 022 501 9921 or visit house re-roofing Auckland.
Frequently asked questions
What are the H1 requirements for roofs?
H1 sets minimum roof/ceiling insulation (R-values) varying by climate zone. The figures have changed recently — confirm current ones with the council, a professional, or MBIE.
What is an R-value?
A measure of thermal resistance — higher means better insulation. H1 sets minimum R-values, varying by zone.
Does re-roofing trigger H1?
It can, depending on scope and current rules — confirm with the council or a building professional. It is also a good chance to improve insulation.
Do requirements vary around NZ?
Yes — H1 uses climate zones, colder regions generally requiring more. Auckland has its own figures.
Where do I find current requirements?
MBIE publishes the Code; the council and building professionals advise. This article is a general intro, not current data.
Topics covered
- H1 building code
- roof R-value rules NZ
- insulation compliance NZ
- H1 roof insulation
- ceiling insulation R-value