Small standalone dwellings up to 70sqm, dubbed granny flats, no longer require a building or resource consent under government changes in place from yesterday.
However, certain conditions must be met for the exemption to apply.
BuildSmart co-director Glen Williamson, of Dunedin, said reducing "red tape" and cost to build was welcome.
"It’s certainly a good thing, I think, for the industry, but it's probably a few pitfalls for owners to probably think about, that’s for sure," he said.
The consent exemption applied only to simple designs meeting the Building Code, where work was carried out by authorised professionals.
A project information memorandum was required from the local council, which could also charge development contributions.
Mr Williamson said builds would still have to meet aspects of the District Plan, such as setbacks and hazard overlays, which could limit some development.
"People still definitely need to talk to professionals, either a draftperson or a builder, and start discussing and understanding some of the issues before they just start going ahead and building something straight away."
S2B Build director Sam Barnett, of Mosgiel, said the changes would produce some savings and significantly reduce time tied up in consenting.
"Around 70 [sq m] would cost you around $400,000 to build — simple construction type like what they're proposing," he said.
"Inside that cost is maybe $5000 of building consent, and that's the only cost you're going to save."
The government’s changes reflected a feeling of trust in licensed builders, he said.
Following details released yesterday, Mr Barnett expected an influx of inquires.
"Hopefully that pulls through into some work for us as builders," he said.
"But it'll be interesting to see what people's thoughts are once they realise what they actually have to do before they can start construction.
"They can't just chip away at it on their weekends."
Platinum Homes Otago licensee Tim Rutherford said the changes were a great initiative, although had a level of complexity people were still working through.
Brent Lucas Builders co-director Brent Lucas, of Dunedin, also said the legislation was a great idea, but people would have to be aware of the exemption criteria.
"I just think it's a good way for people to look after their parents in the future when they need it."
In a statement yesterday, Associate Finance Minister Shane Jones said the exemptions would reduce direct costs by up to $5650 and shorten the build process by 14 weeks.
Legislation underpinning the changes was passed in October.
