Sacred Heart School principal Paul Richardson said a ceiling fan had been left on over the weekend in Nga Maara Hall at his Northeast Valley primary school.
He believed the ceiling fan's motor had malfunctioned and started singeing the ceiling.
Luckily, the school's cleaner Judy Homes noticed ``a bit of a smell'' and raised the alarm.
Mr Richardson said if it had not been for the ``diligence of our cleaner,'' the incident could have been a lot worse.
Fire crews from Dunedin and Willowbank stations extinguished the smouldering fire in the roof of the building quickly, before it could spread.
The damage to the hall's ceiling was not serious, Mr Richardson said.