That will complete the project for the church's centennial celebrations.
The church was officially opened on October 24, 1909.
The church, designed by F. W. Petre, is one of Waimate's prominent historic buildings, standing at the northern entrance to the town's main street.
The restoration started in 2000, with a conservation report on the church, followed by fundraising starting in 2004 for the project.
Now, it is entering its final phase, with the interior restoration expected to cost about $200,000.
Project chairman John Foley said that once completed, the overall project would have carried out about 50 years of maintenance and would last another 50 years.
Scaffolding will go up in the church from Monday, and the interior stage is expected to take about six weeks.
The colour scheme for the interior will be similar to that in the newly restored Opera House in Oamaru, which the project committee visited.
"We were very taken with that [colour scheme]," Mr Foley said.
The work includes restoration of the coffered ceilings and plaster, reinstating some of the interior features and removing the 1970s mahogany joinery.
New lighting will enhance the ceilings, highlight special areas or objects and cater for multiple uses.
One such feature is marble altar rails, which were salvaged from among the church's piles.
They have been cleaned, uncovering Roman lettering and numerals.
The restoration committee has all the funding for the stage, except about $40,000 which will come from the parish.
The rails came from quarries in Carrara, Italy's marble mountain.
They were made to Petre's design, boxed, shipped to New Zealand and reassembled in the church's sanctuary in 1909.
The first two stages of the project, costing about $330,000 and paid for, have been completed.
They included bracing and strengthening the church, a new roof, restoration, cleaning and repairing the exterior.
