Results from asbestos testing at Kaipara College are expected back tomorrow.
The Helensville college has been closed to staff and its 550 students since Friday, after routine tests of water-tightness found asbestos dust in the school hall and the administration building.
Health and safety experts from WorkSafe and the Ministry of Education have been taking air samples and surface swabs inside and outside all of the school buildings.
Principal John Grant said the school would re-open on Wednesday at the earliest.
Wednesday night's prizegiving would be held in the Helensville School Hall.