Resource consent was gained several months ago and building consent was granted last week, with the job going to construction company Calder Stewart, which built the present structure.
The workshop space will increase from 1500sq m to 3000sq m, while the combined engineering and administration space would increase from 800sq m to 1600sq m.
At present at the site there is a metre-high pile of gravel on the expansion site, to compress the ground below, which will then be removed for slab preparation and construction to begin.
Scott chief executive Chris Hopkins said he expected construction to start by the end of the month, with the job finished early next year and staff scheduled to move in by February or March.
While the present 91 jobs at the plant would not increase alongside the doubling of space, Mr Hopkins believed that with sales expected to increase, job numbers would grow in the longer term at the site.
He said the research and development/innovation hub within the building would be expanded, included advanced automation training.
The Dunedin site largely conducts research and development for Scott's robotics division, while its Christchurch site focuses on its mainstay manufacturing of assembly lines for export.
