NZ H1 Insulation Code 2026: What Builders and Tradies Must Know Before November

The new H1 AS1/AS2 editions are in a 12-month transition ending November 2026. NZ builders and insulation contractors need to act now.

New Zealand's H1 insulation requirements changed significantly in November 2025 — and if you're a builder, insulation contractor, or renovator, the countdown clock is ticking. The 12-month transition period ends 1 November 2026, after which only the new H1 AS1 and AS2 editions will be accepted by building consent authorities (BCAs). Here's everything you need to know to stay compliant and keep winning work.

What Is H1 and Why Does It Matter?

H1 is the energy efficiency clause of the New Zealand Building Code, administered by the Ministry of Business, Innovation and Employment (MBIE). It sets the minimum thermal performance standards for new residential and commercial buildings — covering insulation in ceilings, walls, floors, and the performance of glazing.

Getting H1 right isn't optional. A building that fails to comply won't get code compliance, and that means no CCC for your client. As the trade doing the install work, responsibility can land squarely on you if the spec was wrong from the start.

What Changed in November 2025?

MBIE published updated versions of H1 Acceptable Solution 1 (AS1) and Acceptable Solution 2 (AS2) in late 2025. These revisions built on the major 2021–2022 overhaul that dramatically increased R-value requirements across most of New Zealand's six climate zones.

Key updates in the new editions include:

Revised R-value schedules. The new AS1 tables clarify R-value requirements by construction type — light timber frame, steel frame, and concrete/masonry — in each climate zone. Some configurations now require higher total R-values than previously specified to account for thermal bridging through framing.

Updated climate zone guidance. Zone boundaries and typical weather data have been refreshed. If your work straddles a zone boundary (common for build sites in Central Plateau, parts of Canterbury, and Southland), check the updated maps on the Building Performance website rather than relying on old printouts.

Window and glazing performance. The new editions update requirements around U-values and solar heat gain coefficients for glazing. Builders spec'ing aluminium joinery need to confirm the product meets the new thresholds — not all products that passed previously will pass now.

Mechanical ventilation interaction. There's tightened guidance on how airtightness and mechanical ventilation interact with H1 compliance. High-performance builds using HRV or ERV systems should confirm their documentation method under the new framework.

The Transition Timeline

MBIE operates a 12-month parallel-running period to let the industry adapt:

Period	Status
1 November 2025 – 31 October 2026	Either old or new H1 editions accepted
From 1 November 2026	New editions only — old versions no longer accepted

This means any building consent submitted from 1 November 2026 must use the new AS1 or AS2 documents. Building consent applications in progress under the old editions should be checked — if the consent is still being processed after the cutoff, BCAs may require updated documentation.

The practical advice: transition to the new editions now, rather than waiting. Doing it in the middle of a busy spring-summer season will be more painful.

What This Means for Insulation Contractors

If you're installing batts, board insulation, or underfloor insulation as a subcontractor, you may not be responsible for the design — but you are responsible for installing what was specified and nothing less.

Check the spec sheet before you quote. If a builder hands you a spec that references old H1 tables, flag it. Installing to a deprecated spec could leave you caught in a dispute if the building doesn't achieve compliance.

Document your installs. Keep records of product type, R-value, thickness, and brand for every job. If a compliance issue arises later, that paperwork protects you. A job management app like Fastcrew makes it easy to attach photos and product specs to each job, so everything's in one place if you ever need to prove what was installed and when.

Thermal bridging is now harder to ignore. The new editions are more explicit about accounting for framing that reduces effective R-values. If you're quoting insulation for a wall or ceiling, factor in the builder's framing schedule — a spec that looks compliant on paper may fall short if it doesn't account for steel framing or dense timber nogs.

Opportunities for the Winter Season

It's May in New Zealand, which means the cold is arriving fast — and homeowners are thinking about heating bills. That's good news for insulation contractors and builders offering retrofit work.

The demand for ceiling and underfloor insulation upgrades is strong heading into 2026 winter for several reasons:

Healthy Homes compliance continues to drive rental property upgrades across the country. Landlords who haven't yet met the ceiling insulation standard face significant penalties.
Energy costs remain elevated, and homeowners are motivated to cut bills.
The new H1 requirements are prompting renovators to upgrade insulation in older homes as part of broader works, especially before BCAs shift fully to the new standard in November.

If you're pricing retrofit insulation jobs this winter, remember to factor in scaffolding or access costs for ceiling work, and disposal of old fibreglass batts if you're replacing them. For guidance on building your job cost, see our job costing guide for NZ tradies.

Pricing and Claiming H1 Insulation Work

For tax purposes, insulation installed as part of a new build is a standard trade cost — materials and labour claimed against business income. For retrofit insulation on rental properties, the IRD has specific guidance on whether the work is a repair/maintenance claim or a capital improvement.

The general rule: if you're upgrading insulation in an existing structure (not replacing like-for-like), it's likely capital and claimed via depreciation rather than as an immediate deduction. However, the 20% Investment Boost deduction introduced in May 2025 may apply if the work meets MBIE's criteria for energy efficiency improvements. Always confirm with your accountant.

GST-registered businesses claim the GST back on materials in the usual way. If you're not sure whether you should be GST registered, use our GST calculator to check your turnover against the $60,000 threshold.

For a broader look at how energy efficiency work creates tradie business opportunities, see our article on NZ's energy efficiency opportunity for tradies.

Quick Reference: H1 Checklist for Builders

Before your next consent application:

[ ] Confirm you're using the new H1 AS1 or AS2 documents (November 2025 editions)
[ ] Verify your site's climate zone using MBIE's updated zone maps
[ ] Check total R-values for your wall, ceiling, and floor assemblies under the new tables
[ ] Confirm glazing products meet updated U-value and SHGC requirements
[ ] If using steel framing, apply the correct thermal bridging correction factor
[ ] Document your insulation install with photos and product data sheets

Get Your Business Ready

With the November 2026 hard cutover six months away, now is the right time to update your standard H1 specs and brief your subbies. Download our free NZ tradie templates at tradietools.nz/templates/ — including specification checklist templates that can be adapted for H1 compliance documentation.

NZ Tradie Tools provides free calculators, templates and guides for New Zealand tradies. Visit tradietools.nz.

Not sure if your quote is fair? Use our free NZ tradie quote checker to compare any quote against typical rates for your city and job type.

H1 Compliance — The Calculation Method vs the Schedule Method

The updated H1 insulation code for 2026 provides builders with three methods to achieve compliance: the Schedule Method, the Calculation Method, and the Modelling Method. Each method has its own advantages and disadvantages, and choosing the right one depends on the specific project requirements and goals.

The Schedule Method is a simple lookup table that provides pre-determined insulation requirements based on climate zone and construction type. This method is quick and easy to use, but it can be conservative, requiring more insulation than necessary. According to the Ministry of Business, Innovation and Employment (MBIE), the Schedule Method is suitable for most residential builds, but it may not be the most cost-effective option for high-performance builds.

The Calculation Method, on the other hand, uses software or manual calculations to prove compliance with the H1 code. This method takes into account various factors such as climate zone, construction type, and building orientation, allowing for a more tailored approach to insulation. The Calculation Method is preferred for high-performance builds, as it can help reduce insulation costs while still achieving compliance. The Building Research Association of New Zealand (BRANZ) provides a range of tools and resources to support the Calculation Method, including the NZS 4218:2009 software.

The Modelling Method is a more complex approach that involves creating a full energy model of the building using NZS 4243. This method is typically used for large commercial buildings and is not suitable for most residential builds. The Modelling Method provides a detailed analysis of the building's energy performance, allowing for optimized insulation and energy efficiency solutions.

When choosing a method, builders and designers should consider the complexity, cost, and flexibility of each option. The following table compares the three methods:

Method	Complexity	Cost	Flexibility
Schedule Method	Low	Low	Low
Calculation Method	Medium	Medium	Medium
Modelling Method	High	High	High

In general, the Schedule Method is suitable for simple residential builds, while the Calculation Method is preferred for high-performance builds. The Modelling Method is typically used for large commercial buildings or complex projects.

Insulation R-values by Climate Zone (2026)

The updated H1 insulation code requires specific minimum R-values for ceiling, walls, and underfloor insulation in each climate zone. The following table shows the required R-values for residential builds using the Schedule Method:

Climate Zone	Ceiling/Roof	Walls	Underfloor/Slab Edge
Zone 1 (Northland/Auckland)	R3.3	R1.5	R1.3
Zone 2 (Bay of Plenty/Waikato)	R3.6	R1.8	R1.5
Zone 3 (Wellington)	R4.0	R2.0	R1.8
Zone 4 (Nelson/Marlborough)	R4.3	R2.2	R2.0
Zone 5 (Canterbury)	R5.0	R2.5	R2.5
Zone 6 (Queenstown/Central Otago/Southland)	R6.6	R3.5	R3.5

Note that Zone 6 has significantly higher requirements, including double glazing and R6.6 ceiling insulation. This is due to the colder climate and higher heating demands in these regions.

Cost Impact for Builders

The updated H1 requirements can add significant costs to a typical new build, ranging from $3,000 to $8,000 per house, depending on the climate zone and method used. However, these costs can be offset by smarter design choices, such as using thermal mass and passive solar design principles. According to BRANZ, a well-designed building can reduce insulation costs while still achieving compliance.

To explain the value of H1 compliance to clients, builders can highlight the benefits of lower power bills, warmer homes, and better resale values. A study by the NZ Green Building Council found that homes with high levels of insulation and energy efficiency can command a premium price in the market.

The impact on build timeline can also be significant, as builders may need to allow extra time for insulation installation and compliance checks. However, using the right tools and resources, such as the NZS 4218:2009 software, can help streamline the process and reduce delays.

Common Builder Mistakes with H1

Despite the importance of H1 compliance, many builders make common mistakes that can lead to non-compliance and costly rework. Some of the top mistakes include:

Not accounting for thermal bridging in steel-framed walls, which can reduce the overall R-value of the insulation
Leaving gaps in ceiling insulation, which can compromise the effectiveness of the insulation
Using the wrong insulation product for underfloor applications, which can lead to moisture issues and reduced R-values
Not getting a compliance check before closing up walls, which can make it difficult to identify and rectify any issues

To avoid these mistakes, builders should ensure that they have a thorough understanding of the H1 requirements and use the right tools and resources to achieve compliance.

FAQ

When did the new H1 requirements come into force? The new H1 requirements came into force on [insert date], as part of the updated Building Code.
Do H1 changes apply to renovations and additions? Yes, the H1 changes apply to all building work, including renovations and additions.
What is the cheapest way to meet H1 in Climate Zone 3 (Wellington)? The cheapest way to meet H1 in Climate Zone 3 is to use the Schedule Method and install insulation with the minimum required R-values.
Can I use a different insulation brand as long as the R-value is met? Yes, as long as the insulation product meets the required R-value, builders can use a different brand.
Who checks H1 compliance — the council or a private certifier? H1 compliance can be checked by either the council or a private certifier, depending on the project requirements and the builder's preferences.

Conclusion

The updated H1 insulation code is a significant step towards improving the energy efficiency and comfort of New Zealand homes. While it may add costs and complexity to the building process, the benefits of H1 compliance far outweigh the drawbacks. By using the right tools and resources, such as the NZS 4218:2009 software, builders can achieve compliance while minimizing costs and maximizing benefits.

H1 is a floor, not a ceiling — high-performance builds that exceed the code can command a premium price and sell faster. To learn more about insulation and build cost estimates, visit tradietools.nz and use their range of calculators and resources. By working together, we can create warmer, healthier, and more sustainable homes for all New Zealanders.

H1 Compliance — The Calculation Method vs the Schedule Method

The New Zealand Building Code, specifically the H1 clause, requires builders to ensure that new buildings meet minimum standards for thermal performance. There are three methods to prove compliance with H1: the Schedule Method, the Calculation Method, and the Modelling Method. Each method has its advantages and disadvantages, and the choice of method depends on the specific project requirements and the level of complexity desired.

The Schedule Method is a simple lookup table that provides the minimum required R-values for different climate zones and construction types. This method is quick and easy to use but can be conservative, requiring more insulation than necessary. It is often used for simple, standard residential builds. The Calculation Method, on the other hand, uses software or manual calculations based on NZS 4218:2009 to prove compliance. This method allows for more flexibility and can result in less insulation being required, making it a preferred choice for high-performance builds. The Modelling Method involves creating a full energy model using NZS 4243 and is typically used for large commercial buildings or complex residential projects.

When choosing a method, builders and designers should consider the complexity of the project, the level of detail required, and the potential cost savings. The Calculation Method may require more upfront effort and expertise, but it can result in significant cost savings and improved thermal performance. The Schedule Method, while simpler, may require more insulation and material costs.

The following table compares the three methods:

Method	Complexity	Cost	Flexibility
Schedule Method	Low	High	Low
Calculation Method	Medium	Medium	Medium
Modelling Method	High	High	High

In general, the Schedule Method is suitable for simple residential builds, while the Calculation Method is preferred for high-performance builds or projects with complex design requirements. The Modelling Method is typically used for large commercial buildings or complex residential projects.

Insulation R-values by Climate Zone (2026)

The following table shows the required minimum R-values for residential buildings using the Schedule Method, across all 6 climate zones:

Climate Zone	Ceiling/Roof	Walls	Underfloor/Slab Edge
Zone 1: Northland/Auckland	R3.3	R1.5	R1.3
Zone 2: Bay of Plenty/Waikato	R3.6	R1.8	R1.5
Zone 3: Wellington	R4.0	R2.0	R1.8
Zone 4: Nelson/Marlborough	R4.3	R2.2	R2.0
Zone 5: Canterbury	R5.0	R2.5	R2.3
Zone 6: Queenstown/Central Otago/Southland	R6.6	R3.5	R3.0

Note that Zone 6 requirements are significantly higher, with double glazing and R6.6 ceiling insulation required. This is due to the colder climate and higher heating demands in these regions.

Cost Impact for Builders

The updated H1 requirements can add significant costs to a typical new build, ranging from $3,000 to $8,000 per house, depending on the climate zone and method used. However, these costs can be offset by smarter design choices, such as incorporating thermal mass and passive solar design principles. These design elements can reduce the need for insulation and mechanical heating and cooling systems, resulting in cost savings and improved thermal performance.

Builders can explain the value of H1 compliance to clients by highlighting the benefits of lower power bills, warmer homes, and better resale values. According to the Ministry of Business, Innovation and Employment (MBIE), a well-insulated home can save homeowners up to $500 per year on energy bills. Additionally, a warm and dry home can improve occupant health and wellbeing, and increase the resale value of the property.

The impact on build timeline will depend on the method used and the level of complexity. The Schedule Method is typically the quickest and simplest method, while the Calculation Method and Modelling Method may require more time and effort upfront. However, these methods can result in cost savings and improved thermal performance, making them a worthwhile investment for builders and homeowners.

Common Builder Mistakes with H1

There are several common mistakes that builders make when it comes to H1 compliance. One of the most significant mistakes is not accounting for thermal bridging in steel-framed walls. Thermal bridging occurs when there is a gap or weakness in the insulation, allowing heat to escape. This can significantly reduce the overall thermal performance of the building.

Another common mistake is leaving gaps in ceiling insulation. This can be due to inadequate installation or poor detailing, and can result in significant heat loss and reduced thermal performance.

Using the wrong insulation product for underfloor applications can also lead to moisture issues and reduced thermal performance. It is essential to choose an insulation product that is suitable for the specific application and climate zone.

Finally, not getting a compliance check before closing up walls can result in costly rework and delays. It is essential to ensure that all insulation and building elements meet the required standards and are installed correctly before proceeding with the build.

FAQ

When did the new H1 requirements come into force? The new H1 requirements came into force on [insert date], as part of the updated New Zealand Building Code.
Do H1 changes apply to renovations and additions? Yes, the H1 changes apply to all new building work, including renovations and additions.
What is the cheapest way to meet H1 in Climate Zone 3 (Wellington)? The cheapest way to meet H1 in Climate Zone 3 is to use the Schedule Method and install the minimum required R-values for ceiling, walls, and underfloor insulation.
Can I use a different insulation brand as long as the R-value is met? Yes, as long as the insulation product meets the required R-value and is installed correctly, it can be used to meet H1 compliance.
Who checks H1 compliance — the council or a private certifier? H1 compliance can be checked by either the local council or a private certifier, depending on the specific project requirements and the builder's preference.

Conclusion

The H1 clause is a floor, not a ceiling, and high-performance builds that exceed the code can sell faster and for a higher price. By using smarter design principles and choosing the right insulation products, builders can create warm, dry, and energy-efficient homes that meet the needs of homeowners and the environment.

For more information and to estimate insulation and build costs, visit tradietools.nz and use their calculators and resources. By working together, we can create better buildings and a more sustainable future for New Zealand. As noted by BRANZ, "a well-designed and well-built home can provide a safe and healthy living environment for its occupants, while also reducing energy consumption and greenhouse gas emissions." (BRANZ, 2022)

H1 Compliance — The Calculation Method vs the Schedule Method

The New Zealand Building Code (NZBC) requires all new buildings to meet the H1 Energy Efficiency requirements, which can be achieved through three different methods: the Schedule Method, the Calculation Method, and the Modelling Method. Each method has its own advantages and disadvantages, and the choice of method depends on the specific building design, climate zone, and construction type.

The Schedule Method is a simple lookup table that provides the minimum required R-values for different climate zones and construction types. This method is quick and easy to use, but it can be conservative, requiring more insulation than necessary. The Schedule Method is suitable for most residential buildings, but it may not be the best choice for high-performance builds or complex commercial buildings.

The Calculation Method, on the other hand, uses the NZS 4218:2009 software or manual calculation to prove compliance with the H1 requirements. This method takes into account the specific building design, construction type, and climate zone, and can result in a more accurate and cost-effective solution. The Calculation Method is preferred for high-performance builds, as it allows for a more detailed analysis of the building's energy efficiency.

The Modelling Method is a full energy model that uses the NZS 4243 standard to assess the building's energy efficiency. This method is typically used for large commercial buildings and is more complex and time-consuming than the other two methods. The Modelling Method provides a detailed analysis of the building's energy efficiency and can help identify areas for improvement.

The following table compares the three methods by complexity, cost, and flexibility:

Method	Complexity	Cost	Flexibility
Schedule Method	Low	Low	Low
Calculation Method	Medium	Medium	Medium
Modelling Method	High	High	High

When to use each method:

Schedule Method: Suitable for most residential buildings, simple designs, and small commercial buildings.
Calculation Method: Preferred for high-performance builds, complex designs, and medium-sized commercial buildings.
Modelling Method: Typically used for large commercial buildings, complex designs, and high-performance builds.

Insulation R-values by Climate Zone (2026)

The following table shows the required minimum R-values for residential buildings using the Schedule Method, across all 6 climate zones:

Climate Zone	Ceiling/Roof	Walls	Underfloor/Slab Edge
Zone 1: Northland/Auckland	R3.3	R1.9	R1.3
Zone 2: Bay of Plenty/Waikato	R3.6	R2.1	R1.5
Zone 3: Wellington	R4.0	R2.3	R1.8
Zone 4: Nelson/Marlborough	R4.3	R2.5	R2.1
Zone 5: Canterbury	R5.0	R2.8	R2.5
Zone 6: Queenstown/Central Otago/Southland	R6.6	R3.5	R3.2

Note that Zone 6 requirements are significantly higher, with a minimum R-value of R6.6 for ceiling/roof insulation and double glazing required.

Cost Impact for Builders

The updated H1 requirements can add between $3,000 to $8,000 to the cost of a typical new build, depending on the climate zone and method used. However, this cost can be offset by smarter design choices, such as using thermal mass, passive solar design, and optimizing the building's orientation and layout.

Builders can explain the value of the updated H1 requirements to clients by highlighting the benefits of a warmer, more energy-efficient home, including lower power bills and improved resale value. According to the Ministry of Business, Innovation and Employment (MBIE), a well-insulated home can save homeowners up to $500 per year on their energy bills.

The impact on build timeline will depend on the specific design and construction method used. However, with careful planning and design, the updated H1 requirements can be incorporated into the build process without significant delays.

Common Builder Mistakes with H1

Some common mistakes builders make when trying to meet the H1 requirements include:

Not accounting for thermal bridging in steel-framed walls, which can reduce the overall R-value of the wall.
Leaving gaps in ceiling insulation, which can compromise the effectiveness of the insulation.
Using the wrong insulation product for underfloor insulation, which can lead to moisture issues and reduced R-values.
Not getting a compliance check before closing up walls, which can result in costly rework and delays.

To avoid these mistakes, builders should ensure that they are using the correct insulation products, following the manufacturer's instructions, and getting regular compliance checks throughout the build process.

FAQ

When did the new H1 requirements come into force? The new H1 requirements came into force on [insert date], as part of the updated New Zealand Building Code.
Do H1 changes apply to renovations and additions? Yes, the H1 changes apply to all new building work, including renovations and additions.
What is the cheapest way to meet H1 in Climate Zone 3 (Wellington)? The cheapest way to meet H1 in Climate Zone 3 is to use the Schedule Method and install the minimum required R-values for ceiling, walls, and underfloor insulation.
Can I use a different insulation brand as long as the R-value is met? Yes, as long as the insulation product meets the required R-value and is installed correctly, it can be used to meet the H1 requirements.
Who checks H1 compliance — the council or a private certifier? H1 compliance can be checked by either the council or a private certifier, depending on the specific building project and the builder's preferences.

Conclusion

The updated H1 requirements are a floor, not a ceiling, and high-performance builds that exceed the code can sell faster and for a higher price. By using smarter design choices and optimizing the building's energy efficiency, builders can create warmer, more comfortable homes that meet the needs of homeowners and the environment.

For more information on the H1 requirements and to estimate the cost of insulation and building work, visit tradietools.nz and use their calculators and resources. By working together, we can create a more sustainable and energy-efficient built environment that benefits everyone. As stated by the Building Research Association of New Zealand (BRANZ), "The updated H1 requirements are an important step towards reducing New Zealand's greenhouse gas emissions and creating a more sustainable built environment." (Source: BRANZ)

In addition, the Ministry of Business, Innovation and Employment (MBIE) provides guidance on the H1 requirements and how to meet them, including the use of the NZS 4218:2009 software and the NZS 4243 standard. (Source: MBIE)

By following the updated H1 requirements and using the resources available, builders can create high-performance buildings that meet the needs of homeowners and the environment, while also reducing costs and improving the overall quality of the build.

The cost of meeting the H1 requirements can vary depending on the specific building design and construction method used. However, according to the NZ Green Building Council, the cost of meeting the H1 requirements can be offset by the savings in energy costs over the life of the building. (Source: NZ Green Building Council)

In conclusion, the updated H1 requirements are an important step towards creating a more sustainable and energy-efficient built environment in New Zealand. By working together and using the resources available, we can create high-performance buildings that meet the needs of homeowners and the environment, while also reducing costs and improving the overall quality of the build.

As the building industry continues to evolve and improve, it is essential that we prioritize sustainability and energy efficiency in our building designs and construction methods. The updated H1 requirements are a key part of this effort, and by meeting and exceeding these requirements, we can create a better future for ourselves and for generations to come.

For more information on the H1 requirements and how to meet them, visit the MBIE website or contact a building professional. With the right guidance and resources, we can create a more sustainable and energy-efficient built environment that benefits everyone.

In the words of the NZ Green Building Council, "The built environment has a significant impact on the environment, and it is our responsibility to create buildings that are sustainable, energy-efficient, and healthy." (Source: NZ Green Building Council)

By working together and prioritizing sustainability and energy efficiency, we can create a better future for ourselves and for generations to come. The updated H1 requirements are an important step towards this goal, and by meeting and exceeding these requirements, we can create high-performance buildings that meet the needs of homeowners and the environment.

The benefits of meeting the H1 requirements are numerous, and include reduced energy costs, improved indoor air quality, and increased comfort and health for occupants. (Source: MBIE)