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NZ Building Code · Standards & CodesNZBC Acceptable Solutions & Verification Methods
A plain-English rundown of the current NZ Building Code Acceptable Solutions and Verification Methods, with editions, effective dates and transition windows.
Acceptable Solutions and Verification Methods are the government-published compliance pathways for the NZ Building Code — follow the Acceptable Solution and your work is deemed to comply with that clause. This is a quick map of the current documents across the clauses builders touch most, showing the edition, when it took effect and any transition window where the old version is still valid.
What these documents are
Every clause of the Building Code can have one or more Acceptable Solutions (a prescriptive recipe) and Verification Methods (a calculated or tested pathway). Each one has a scope, a current status and a free download.
- Acceptable Solution – a step-by-step way to meet the clause without further proof.
- Verification Method – a way to show compliance by calculation or test.
- Where a new edition has replaced an old one, there is usually a transition window during which the previous version is still valid for consent applications.
H1 Energy Efficiency
H1/AS1 6th edition is the current Acceptable Solution for clause H1 Energy Efficiency, published 27 November 2025. The previous 5th edition Amendment 1 is transition-only.
- H1/AS1 6th edition (current): 6 climate zones; Roof R6.6 in all zones; Walls R2.0; Slab R1.5 / R2.5+; Windows R0.46–R0.50. The Schedule method has been removed.
- H1/AS1 5th ed Amendment 1 (transition only): still valid for consent applications until 26 November 2026. Covers the Schedule method (≤30% glazing), the Calculation method and Modelling, across 6 zones.
B1 Structure
B1 is the structural clause. The Acceptable Solution points to NZS 3604 for standard timber framing, and the Verification Method covers foundation geotechnical design.
- B1/AS1 2nd edition (current): effective 28 July 2025. References NZS 3604:2011 for timber-framed buildings up to 10m / 3 storeys, plus Building Product Specifications (BPS). Includes Amendment 11 (foundation 2× D12 bars) and Amendment 15 (cantilever balustrade).
- B1/VM2 2nd edition (current): the Verification Method for foundations, renamed from B1/VM4 to B1/VM2. Covers geotechnical design, with timber piles handled via BPS.
B2, C, E2 and E3
The remaining high-use documents cover durability, fire, and moisture — several with their own transition windows.
- B2/AS1 3rd edition (durability, current): effective 28 July 2025. Uses 50 / 15 / 5 year durability tiers, with timber treatment per BPS. Transition until 31 July 2026.
- C/AS1 + C/AS2 + C/VM2 2nd edition (fire, current): C/AS1 for small buildings, C/AS2 for other risk groups, C/VM2 for verification. Fire testing is centralised in BPS. Transition until 31 July 2026.
- E2/AS1 4th edition (external moisture / weathertightness, current): covers cavity construction rules, building wrap and flashings for timber-framed buildings. Cavity construction is mandatory for most claddings, with a 20mm minimum cavity; a risk matrix score above 6 means a cavity is required, and sheathing is mandatory in Extra High wind.
- E3/AS1 (internal moisture / wet areas, current): the Acceptable Solution for E3 Internal Moisture.
Plain-English guide, not advice. This page helps you understand and navigate the rules — it is general information, not design, engineering or consent advice, and it does not reproduce the copyrighted tables of NZS 3604 or any Standard. Always check the current Standard or Acceptable Solution and your BCA, and use a suitably qualified LBP, engineer or QS where it matters.
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Common questions
Which H1 energy efficiency edition applies right now?
H1/AS1 6th edition is the current Acceptable Solution, published 27 November 2025. The previous 5th edition Amendment 1 is transition-only and stays valid for consent applications until 26 November 2026. The 6th edition removed the Schedule method.
What does B1/AS1 reference for timber framing?
B1/AS1 2nd edition (effective 28 July 2025) references NZS 3604:2011 for timber-framed buildings up to 10m / 3 storeys, plus Building Product Specifications. It includes Amendment 11 (foundation 2× D12 bars) and Amendment 15 (cantilever balustrade).
When is a drained cavity required under E2/AS1?
Under E2/AS1 4th edition, cavity construction is mandatory for most claddings, with a 20mm minimum cavity. A risk matrix score above 6 means a cavity is required, and sheathing is mandatory in Extra High wind.
Which Acceptable Solutions have transition windows I should watch?
Several current editions have transition periods where the previous version is still valid: H1/AS1 5th ed Amendment 1 until 26 November 2026, and B2/AS1 3rd edition and the C-clause fire documents (C/AS1, C/AS2, C/VM2) until 31 July 2026.
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