Community groups and the Oamaru Opera House will share the Oamaru courthouse with the Oamaru District Court when it reopens.
The Waitaki District Council and the Ministry of Justice do not expect any issues of the joint use to arise.
The cost of the work to earthquake-strengthen and refurbish the building is still unknown.
Waitaki Mayor Gary Kircher said the council was still working on how much it would cost, but that work was expected to finish soon.
"There is still work going on, just fine-tuning, what the dollar amounts are going to be for the work. We've got approximate costings, but we just don't want to go out with something that is not right,'' he said.
But council chief executive officer Michael Ross said yesterday it would be funded through an internal loan, which would require council approval.
Mr Kircher said the council would invite community groups to use the building and the courthouse could accommodate overflow from the Opera House "when they've got big events on''.
"Potentially, it could be some group having monthly meetings there,'' he said.
"As far as permanent tenants go it's certainly a lot more difficult, just because of the need to keep the space flexible.''
The council was not actively pursuing other groups to use the space, he said.
Last week the Justice Minister announced the courthouse would be transferred from the ministry to the council and the ministry would lease back the building for court services.
Yesterday, the ministry's general manager commercial and property, Fraser Gibbs, said the use of the courthouse building when not in use for court services would be decided by the council "as the owner and manager''.
"However, the fundamental principle is that the sharing arrangement satisfies the dignity, confidentiality and security requirements of the court,'' he said.
A ministry spokesman said the ministry did not discuss "specific security arrangements in our courts''.
Mr Ross said the council would manage the shared use and the surrounding security issues during the minimum 10-year-lease "with existing council resources and contractors'' and that the council and ministry would both have security systems in place.
"We will work collaboratively to ensure the safety of the public,'' he said.
He could still not provide the cost of the "nominal purchase'' of the courthouse.
Oamaru lawyer Bill Dean, who has previously said the building would cost at most $350,000 to strengthen, said the council employed the same quantity surveyor he had to work out the costs.
"Costings may have gone up, but at the same time I don't think the council is going to need to do all of the things that [the engineer] initially said would bring it up to [100%]. To get it to 67% is very different.''
The ministry initially indicated it would cost $6million to strengthen the building.
After Mr Dean's report, the estimate was cut to $2million.
