Hundreds of Auckland homeowners may have to apply for new resource consents, after the Auckland Council admitted it had misinterpreted its own rules.
The council said 430 resource consents are affected in suburbs like Grey Lynn and Ponsonby, where special character rules apply.
"The special character overlay zones are in the older part of town and so you're looking at sort of Grey Lynn, Ponsonby, there's some on the [North] Shore," Resource Consents general manager Ian Smallburn said.
"Traditionally they're single house zones so people that would be looking to undertake additions and alterations to their properties, or potentially building new homes."
The council said the consents were granted between December 2016 and December 2017.
It was urging resource consent holders to reapply as soon as possible, so they weren't left open to the risk of a legal challenge to their consent.
It would take a matter of days for the new consents to be issued, because most updates to them should be relatively straightforward, the council said.
Affected homeowners would be contacted in the next two to three weeks.
Environment and planning lawyer Nicky McIndoe said the bungle showed just how complicated the city's planning rules were.
She said it wa a hassle for those caught up in it.
"They've done their best to get the resource consents to authorise works which they are undertaking on their properties and through no fault of their own, find themselves in a situation where they now need to go back and patch up the situation to ensure that they're not in breach."
The council had not yet looked into how much it could cost ratepayers.
It will be looking at changing the Unitary Plan to clarify the rules, but that process could take at least a year.
The problem arose when the Environment Court disagreed with how the council was applying the extra rules that applied in special character areas.
It said those rules should not take precedence over the underlying zoning rules and both should apply when resource consent applications were considered.
The council said some homeowners may have to make changes to their plans to comply with the new interpretation of the rules.
Auckland builder Charlie Bailey, from Salamander Build, said any hold-ups or plan changes have flow-on effects for people like him.
"It's a nightmare really, you know you've got everything planned and it's really hard to book in your subbies, you've got workers that work for you, sometimes you've got to lay them off or you've got to try and pull other jobs forward. It's a bit of a nightmare and I just don't understand how they could get it so wrong to be honest."
The owners of up to five properties have been told to stop building work while the issues were sorted out.
The council said it would pay for the new consents and look at compensation in some cases.
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