A fire that started in a garbage bin outside Cambridge Memorial Hospital spread to the building itself, Waterloo Regional Police say.
The fire was spotted shortly before 2 a.m. Monday by a police officer.
Firefighters were called in to extinguish the flames as investigators pinpointed the garbage bin as the likely source of the fire.
A 38-year-old man is charged with arson with disregard for human life.
No injuries were reported, but damage is estimated at $25,000.