Ottawa Fire Crews say they were called to Kanata Montessori School just after midnight on reports of trees on fire in the area.
When they arrived, they confirmed a fire in a portable building near the school ground.
Firefighters had the blaze under control less than half an hour later. They say there were no civilians in the area at the time, and no firefighter injuries were reported.
The fire caused roughly 50,00 in damages. The cause of the blaze is under investigation. An Ottawa Fire Services Investigator will attend the scene.