What changed in the granny flat exemption on 8 October 2026?
MBIE's October update makes the 70 m² granny flat exemption easier to use. Here's what changed, and what didn't.
Updated 1 October 2026 · By CAD Consultants Ltd
From 8 October 2026, the granny flat exemption allows certified composite structural products (such as some SIP panels and solid timber systems with a CodeMark certificate) and makes it easier to use existing water supply, wastewater and stormwater services. The core rules haven't changed: up to 70 m², single storey, detached, simple design, at least 2 m from boundaries and other dwellings, built by Licensed Building Practitioners, with council notified before and after.
What's new from 8 October 2026
1. More building products
Granny flats can now use certified composite structural building products, including some Structural Insulated Panel (SIP) and solid timber systems. Each product must be used within the scope and limits of its CodeMark certificate and the manufacturer's instructions. This opens the exemption to more prefabricated and off-site manufactured homes.
2. Using existing services
- Council or utility connections: you may be able to use or modify the property's existing water, wastewater and stormwater connections, if the provider agrees the connection is suitable. You'll need the provider's approval, but not a building consent for the change.
- Existing on-site systems (rainwater tanks, wastewater treatment, stormwater) can be used or upgraded if they have enough capacity and comply with the Building Code.
- New on-site systems are allowed where council services aren't available or can't take another connection.
What hasn't changed
| Condition | Rule |
|---|---|
| Size | Up to 70 m² floor area |
| Form | New, single storey, detached, simple design |
| Distance | At least 2 m from legal boundaries and other residential buildings |
| Construction | Lightweight roof and frame; simple plumbing and drainage; must meet the Building Code |
| Who builds | Restricted building work done or supervised by Licensed Building Practitioners |
| Council | Apply for a PIM before you start; give council the completion records when finished |
Development contributions and service connection costs can still apply. Whether you also need a resource consent depends on the national standard for minor residential units and your district plan.
Where people still get caught
Step outside one condition and the whole exemption falls away, which means a full building consent. Common traps: a wall closer than 2 m to the boundary, a level-entry shower that needs a waterproof membrane, or a design that isn't "simple". The October changes make the exemption easier to use. They don't make it forgiving.
See our granny flat design service for how we design flats that tick every box.
Common questions
Can I now use a prefab or SIP granny flat without a building consent?
Possibly. From 8 October 2026, certified composite structural products such as some SIP and solid timber systems can be used under the exemption, but only within the scope of their CodeMark certificate and the manufacturer's instructions. The flat must still meet every other condition.
Can my granny flat share the main house's water and sewer connection?
From 8 October 2026 you may be able to use or modify the existing council or utility connections, if the provider agrees the connection is suitable. You'll need the provider's approval, but not a building consent for that change.
Did the 70 m² size limit change?
No. The exemption still applies to new, detached, single-storey granny flats of up to 70 m², at least 2 m from boundaries and other residential buildings.
Do I still need a PIM?
Yes. You apply to council for a Project Information Memorandum before building, and provide completion records when the work is finished.