The government has announced consultation on a move that would force councils to allow buildings up to 60 square metres in certain areas, without requiring a consent.

It sets out the policy as a way of making it "easier to build granny flats and increase the supply of affordable homes for all New Zealanders".

NZ First leader and Acting Prime Minister Winston Peters announced it alongside Housing and RMA Reform Minister Chris Bishop after the Monday Cabinet meeting.

Prime Minister Christopher Luxon was overseas, headed to Japan for an official visit.

The move follows a commitment in the National-NZ First coalition agreement, which requires the government to "amend the Building Act and the resource consent system to make it easier to build granny flats or other small structures up to 60 square metres, requiring only an engineer's report".

However, the discussion document released as part of the announcement makes clear the requirement for an engineer's report was being abandoned, as it could mean additional costs and engineering services.

"Instead, we are proposing that all work is conducted or supervised by competent professionals under current occupational licensing requirements to ensure all building work will meet the Building Code," the documentation states.

Peters said the policy would "make it more affordable for families to live the way that suits them best".

"High housing costs have a greater impact on Māori, Pasifika, and people with disabilities, as well as seniors - so unlocking the space in the backyards of family members opens the door to new ways of living," he said in a statement.

"We know granny flats are a great option for seniors, but they're also increasingly popular with other families such as those who want homes where their university-age children can live at home but maintain some privacy and independence, or families who want to provide extra support to a loved one."

Bishop said many councils already allowed granny flats without requiring a resource consent.

"But there's a lack of consistency and different standards across the country. We're proposing a National Environmental Standard (NES) to require all councils to permit a granny flat on sites in rural and residential zones without resource consent. An NES means changes can come into force quickly.

"We are determined to get on top of how expensive it is to build a house in this country."

It would apply in rural and residential zones, but the documents called for feedback on whether it should apply in other areas like mixed-use zones.

The changes would also need to be balanced against things like flood risk, so some district plan rules would still apply. As well as building size, other restrictions include percentage of a property able to be covered in buildings, and distance from a boundary.

He said he would hope the move would not leave councils worse off because the fees from consenting were meant to be cost recovery, and he would be "horrified" if they were making money off it. He pointed to the ACT Party's proposal to share GST with councils, with the aim of incentivising the building of new houses, as another way the government was looking to support local authorities.

Bishop said the granny flats would not be allowed to be more than one storey, would need interconnected smoke alarms, and be distant enough from the boundary to prevent the spread of fire to other buildings.

He said the consultation is a couple of months long to ensure they get the settings right.

Consultation is open from today, 17 June, until 5pm on 12 August. Final policy decisions will be made later in 2024, expected to be in place by mid-2025.

This story was originally published by RNZ