The innovative permanent block will feature five "learning studios" for years 5 and 6, and possibly years 7 and 8.
The block will be built on the upper netball courts behind the library. The site will be closed in the first week of the school holidays that start this weekend.
Construction is is expected to be completed by December.
School principal John Western said plans for the block had been designed for the past 18 months but confirmation of ministry funding had been announced three weeks ago.
The new facility would help reduce overcrowding, he said.
"It's important because we have a lot of relocatable classrooms and we wanted to provide permanent classrooms for the future of our school."
Queenstown Primary has 608 pupils in years 0 to 6 on its roll. Six years ago, the school's pupil population was about 400. Almost half of the classrooms are still relocatable.
