Quality · Compliance
Granny flat materials and Building Code rules in New Zealand
What the Yard 37 and Yard 57 are made of, what changes for New Zealand, and the rules that apply to a granny flat built under the 2026 exemption.
Materials, element by element
From the manufacturer's quotation for our reference units (October 2026). Every item is confirmed in writing in your quote.
Galvanised steel frame
Powder-coated Q235 steel, bolted with stainless fixings: 150 × 210 × 3.0 mm columns and 4.0 mm corner castings on our reference units. Near the coast, the fluorocarbon (PVDF) coating option extends service life in salt air. Whether this bolted frame counts as a lightweight steel frame under the exemption is one of the questions open with MBIE.
Insulated sandwich panels
Walls of 75 mm EPS (Standard) or 100 mm EPS (Premium) between two skins of 0.35 mm colour steel; 75 or 100 mm PU and rock wool are available. The New Zealand version has a thicker insulated roof than the Australian 50 mm panel, sized by the H1 calculation.
Windows and doors
Thermal-break aluminium, double glazed, with flyscreens; thermal-break aluminium entry door. Glazing performance is set by the H1 calculation for your climate zone.
Floor and finishes
Cement board and bamboo plywood with a PVC wear layer, SPC click flooring in the finish schedule, and floor insulation of at least R1.3, the H1 minimum for a suspended floor; embossed metal cladding outside.
Electrical
230 V single-phase installation wired at the factory to AS/NZS 3000, with safety switches (RCD/RCBO). Because that work was done overseas, a New Zealand electrical inspector assesses the installation and issues a record of assessment before connection. As the importer, you sign a supplier declaration of conformity for the installation: we prepare it with the test results, the declarations for each fitting and the wiring layout, and go through it with you. The licensed electrician named in your quote then connects it and issues the certificates. Your quote confirms the inspection and its cost.
Plumbing
Four labelled connection points: cold, hot, grey water and sewer. Under the exemption, plumbing and drainage follow set acceptable solutions, with no more than 30 fixture units and no pumped systems. We check the layout against these conditions before your order; your registered plumber and drainlayer make the connections.
The rules in New Zealand
General information as at 23 October 2026, not advice for your section. Your designer certifies the design and your council issues the PIM: neither role is ours.
| Topic | Rule | Source |
|---|---|---|
| Granny flat exemption | A new, stand-alone, single-storey home of up to 70 m², measured between the inside faces of the external walls, can be built without a building consent if every condition is met. It must still comply with the Building Code. Whether a home manufactured overseas, and a bolted steel frame like those of our units, can use the exemption is an open question with MBIE (asked on 23 October 2026). Until MBIE answers in writing, we take no deposit for a project that relies on the exemption; it can go through a building consent instead. | Building Act 2004, s 42B and Schedule 1A (in force 15 January 2026, amended 8 October 2026) |
| Design conditions | A detached dwelling with its own kitchen; no mezzanine; up to 4 m high above the floor; floor up to 1 m above the ground; lightweight steel or timber frame, or a certified composite structural product; at least 2 m from boundaries and other homes; roof cladding up to 20 kg/m² and wall cladding up to 220 kg/m²; its own point of supply for electricity (clause 2(1)(k)): your designer confirms how your section meets it, and your quote confirms any separate connection; electric or gas heating only; no level-entry shower that needs a waterproof membrane. | Schedule 1A, clause 2(1) |
| Plumbing and drainage | Designed to set acceptable solutions for surface water (E1), water supply (G12) and foul water (G13); no more than 30 fixture units under AS/NZS 3500; no pumped systems; main drain at least DN100 at 1:60, branch drains at least DN65 at 1:40. | Schedule 1A, clause 2(1)(i) and 2(2) |
| PIM | Compulsory for every exempt granny flat and issued by the council within 10 working days of a complete application. No building work may start before it is issued, and it lapses after two years if the work is not finished. A dwelling built in a factory needs no second PIM. | Building Act, ss 32 to 34A |
| Authorised people | Design, building, plumbing, drainlaying and electrical work must be done by people authorised to do it: a licensed or registered designer, Licensed Building Practitioners for restricted building work, registered plumbers and drainlayers, licensed electricians. | Building Act, s 42B(3)(b) |
| After completion | Within 20 working days, the owner sends the council the records of work, the electrical certificates, the final plans and the designer's certificate of work. Failing to do so carries an infringement fine of up to $1,000. | Building Act, s 42B(4) and (5) |
| Planning | One minor residential unit per site can be a permitted activity in residential, rural, mixed use and Māori purpose zones, up to 70 m², where there is a principal home on the site and setback and site-coverage standards are met. | National Environmental Standards for Detached Minor Residential Units, 2025 |
| Structure (B1) | Loads from AS/NZS 1170, including wind (Part 2), and earthquake actions from NZS 1170.5. Foundations to the MBIE granny flat foundations guidance or a specific engineering design. | B1/VM1, 2nd edition (2025); MBIE Granny Flats Foundations Guidance (2026) |
| Weathertightness (E2) | The acceptable solution E2/AS1 covers timber-framed buildings. A steel-framed panel unit shows compliance another way, for example as an alternative solution based on the manufacturer's details and evidence. | E2/AS1, 4th edition (2025) |
| Energy (H1) | Minimum construction R-values of R2.6 for roofs, R1.0 for walls and R1.3 for floors other than slab-on-ground, plus a whole-building calculation. The previous edition can be used only until 26 November 2026. | H1/AS1, 6th edition (27 November 2025) |
| Electrical | Installation to AS/NZS 3000 (the Wiring Rules). For an imported building, the importer provides an installation supplier declaration of conformity with a certificate of compliance or a record of assessment, and declarations for medium- and high-risk fittings. An electrical safety certificate is issued after connection. | WorkSafe, electrical safety in imported buildings (May 2024) |
| Asbestos | Importing any product that contains asbestos is prohibited unless the EPA grants a permit. There is no minimum threshold. | Imports and Exports (Asbestos-containing Products) Prohibition Order 2016 |
| Biosecurity | Containers arrive with a biosecurity declaration, are unpacked at an MPI-approved transitional facility and checked for contamination. Wood packaging must carry the ISPM 15 mark. | Ministry for Primary Industries, containers and cargo |
| Duty and GST | Duty is 0% for goods of Chinese origin with a proof of origin (5% otherwise). GST of 15% applies to the customs value plus freight and insurance, with Customs and MPI levies of $118.44 plus GST per import entry. | Working Tariff Document, 9406.20; GST Act 1985, s 12; NZ Customs, goods levies |
| Consumer rights | Consumer guarantees that cannot be excluded for consumers, and implied warranties for residential building work, with defects notified within 12 months to be remedied. | Consumer Guarantees Act 1993; Fair Trading Act 1986; Building Act, ss 362I to 362Q |
What we require from every factory
- Business licence, checked on China's national registry.
- Detailed specification: steel grade and thickness, panels, insulation, windows, floor.
- Structural drawings and calculations for your New Zealand designer or engineer.
- Asbestos test reports from an accredited laboratory, and independent sampling before shipping.
- Wiring layout to AS/NZS 3000 and the declarations or approvals for each electrical fitting, checked before your order.
- Plumbing layout with its fixture-unit count, installation guide and written warranty item by item.
Your side of the project
- Applying for your PIM with your designer, before production starts, and checking the planning rules for your section.
- Accepting the designer, Licensed Building Practitioner and licensed trades named in your quote, who contract with you directly for the site works included in the turnkey price.
- Paying council and Watercare charges directly (counted in the turnkey price at the amount for your address).
- As the importer, signing the supplier declaration of conformity for the electrical installation, which we prepare with you.
- Truck and crane access to your section, checked with you before the quote.
- The completion documents sent to your council within 20 working days, development contributions paid within the same 20 working days, and insurance of the unit once delivered.