A prisoner has been accused of vandalising the sprinkler system at Napier's courthouse, causing extensive water damage and forcing it to shut for three weeks.
The flooding happened on Friday and the Ministry of Justice said it was due to be closed for a week.
But on Thursday a spokesperson told RNZ the Hastings Street building would now be out of action until the week of 6 November.
District Court proceedings will be heard at Hastings District Court in the meantime - but the court said there would be delays, and some hearings might be adjourned and rescheduled.
There were no matters for the High Court set down for the next two weeks.
The police said no charges had been laid but inquiries were continuing.