The second fire to damage part of Richmond School in just one month is being treated as suspicious by police.
Emergency services were called to the Napier school at 1.40pm on Saturday, after a fire started on a fence and spread to a single-storey building.
Two fire engines were needed at the scene and the fire was under control by 2.30pm.
Principal, Shane Foster said it was "disappointing" but was glad there was no "serious" damage and that no one had been hurt.
"The community reacted pretty fast in terms of notifying the fire brigade, because they got there before some serious damage, otherwise we could have lost everything."