The 1883 Thames St courthouse was closed in late 2011 after being classed as earthquake-prone.
Court services were relocated to the nearby Oamaru Opera House and then to a portable facility in Humber St in 2014.
After a short delay caused by poor weather, earthquake-strengthening work started in late February.
Scaffolding was erected around the building before it was cloaked in white plastic wrap to make it weatherproof and reduce dust and noise.
Strengthening work, which involved steel support rods being installed throughout the building, was completed several weeks ago, as was work to replace the building's roof. Its guttering was also re-contoured.
Waitaki District Council property manager Renee Julius said it would take ''a week and a-half or two weeks'' for the scaffolding to be removed, and external cleaning of the building would take about the same length of time.
As the building's Oamaru stone was unable to be water-blasted, it would be steam-cleaned instead.
The wrap will be sent to Invercargill to be recycled, she said.
Internal work continued to prepare the building for the return of court services, likely to be in late September or early October after the Ministry of Justice pushed out the initial time frame of early September.
The delay came after ministry staff visited the courthouse to inspect progress and confirmed their operational requirements would be met once back in the building.
Additional work was identified in security and technology spaces, the ministry told the Otago Daily Times last month.
The work was incorporated into the current work schedule, as it was ''more cost-effective and less disruptive'', Ministry of Justice commercial and property general manager Fraser Gibbs said.
While the cost of the work has not been disclosed, it was within the council's $900,000 budget, funded through its endowment fund.
After long negotiations, an agreement was reached between the council and the ministry in 2016 that resulted in the council taking ownership of the building and agreeing to lease it back to the ministry.
