Researchers plan to make building a granny flat even simpler

Thursday, 15 January 2026

Designs for exempted granny flats will need to be single storey and simple in shape, such as this design by Compac Homes, which won Tiny Home of the Year in 2025.

Homeowners wanting to make use of the granny flat legislation - which takes effect as of today - will be able to access free-to-download architectural plans, after Auckland University researchers received funding from Branz.

Branz, New Zealand’s independent building research body, has granted $220,000 for the 18-month project led by Professor Anthony Hōete.

Auckland University Professor of Architecture Anthony Hōete says granny flats are not just for nanas, but can respond to a variety of housing needs.

Hōete, of Ngāti Awa descent, says the open source plans for buildings up to 70 square metres will be of benefit to many, particularly those wanting to live intergenerationally.

“They could be for kaumātua [respected elders], it could be transitional housing. Maybe the kids want a couple of extra rooms outside.”

It could help where the main house on the property is overcrowded, he says.

Hōete says the initial phase of the research will be to investigate 1000 different properties “to understand the nature of how we live and what our sections look like”.

They then will design half a dozen types, with full sets of drawings, documentation and specifications for people to download at no cost.

Small stand-alone dwellings of up to 70sqm need not feel small, as this bedroom in Sheila and Noel Boddington’s Shaye’s Tiny Homes house shows: This one is large enough to include a dressing room.

The Building and Construction (Small Stand-alone Dwellings) Amendment Bill allows for standalone dwellings of up to 70 square metres to be built without a consent, so long as certain conditions are met.

His team is partnering with Context Architects, who he says “have done a lot of work in affordable housing for Kāinga Ora”.

The idea is for homes that are affordable, that look good, and are sustainably built. The build price is expected to be between $3500 and $4000 per square metre, or less than $300,000 total.

The granny flat legislation will make life easier for some fans of tiny homes, such as those visiting the Tiny House Expo, but they will need to own land with a primary residence.

Some designs will have more of a focus on universal design, which is making homes suitable for people with disabilities, including older people.

Hōete says the project is exciting. “It may be the right time. We’ve come out of a difficult couple of years economically.

“This is going to give people tangible options where they can be a little bit self-empowered, they can choose from a suite of schemes, go and find a builder and do it.“

The granny flat research is one of 22 new projects that will share $11.5 million in Building Research Levy funding.

A Building Research Levy of 0.1% is collected from all building consents over $20,000. Each year, an independent group decides on projects to fund that deliver practical solutions to reduce costs, lift quality, and improve resilience and sustainability in New Zealand buildings.

Other research projects funded in the $11.47m round include:

Whakamaru i te Rangatahi - Navigating housing solutions for rangatahi and whānau, by Pūrangakura Māori and Indigenous Research Centre
Architecture for all: Building equity through AI and whānau-centred design, by Te Wānanga o Aotearoa
Spatial data refresh: Updating Branz maps for safe, resilient buildings, by Branz
Retrofitting homes to cut energy bills and improve comfort, by Centre for Research Evaluation and Social Assessment (CRESA)
Closing the gap between design and reality for healthier homes, by Branz
Your Home, Your Way: A DIY Tool for affordable, custom energy retrofit solutions, by Massey University
From Sunlight to Savings: Reducing energy costs for whānau in social housing, by Te Āhuru Mōwai.

Granny flat legislation basics

1. It’s actually called the Building and Construction (Small Stand-alone Dwellings) Amendment Act 2025, and was passed by Parliament in October 2025.

2. The building consent exemption will commence on January 15, meaning homeowners won’t need a standard building consent to build a qualifying granny flat.

3. The exemption applies to self-contained dwellings up to 70 square metres in floor area.

4. The building must have a simple design, comply with the Building Code, and be built or supervised by an LBP (licensed building professional).

5. The local council must still be notified before construction begins and after it’s finished. Homeowners apply for a Project Information Memorandum (PIM), and are liable to pay infrastructure contributions.

6. The legislation is intended to boost housing supply, with estimates of about 13,000 granny flats built over the next 10 years. It was part of the National–New Zealand First coalition agreement.