The Dunedin secondary school's administration block has remained untouched since it was built in 1958.
But thanks to a grant from the Ministry of Education, it will get a timely modernisation.
Principal Philip Craigie said a new main entrance would be created at the north end of the present building, which would make the school's main entrance "much more obvious".
Many of the present offices, guidance room and sick bays would be relocated, and new toilets would be installed for the school hall.
A new kitchen would also be built to serve the school hall and the staffroom, which would have more work space for teachers and a new toilet area, he said.
The present courtyard would be partially covered by a glass atrium roof which would allow more flexibility for people using the hall.
Mr Craigie said revamping the school's present entrance to the hall, and providing toilets and a kitchen, meant it could be used independently.
"You'll be able to have access to the hall without needing access to the school, which will be useful for community functions."
The development was expected to cost about $1 million, and funding was provided in the Ministry of Education's Five-year Property Fund.
Mr Craigie said once the plans were approved and the tenders for the work had been let, the building would be completed in four stages to keep disruption to school operations at a minimum.
He was still waiting for final approval of the project, but hoped construction would begin later this year.
"This is great to see. It's well overdue, and it will make the face of the school so much more appealing."
