An overheating chimney connected to a malfunctioning emergency generator was the cause of a blaze that caused $450,000 worth of damage at an Ottawa retirement home, fire officials say.

A dozen rooms at Windsor Park Manor were damaged by the fire, which started just before 5 p.m. Thursday. The rooms also suffered water damage.

The residents who lived in the affected rooms can thank the sprinklers for alerting them, as well as staff members, to the fire. The staff then moved to evacuate the rooms promptly, according to Windsor Park's general manager.

"They were immediately evacuated because the water sprinkler started," said Diane Thauvette-Chenier, "The building, of course, has the latest technology with fire walls everywhere."

She thinks the damage could be worse than estimated because of water from the firefighters. One resident said the water in some of the rooms was about 30 cm deep.

"It was just pouring through, you could see it going into rooms on either side of the corridor," Phyllis Lockyear said.

Twelve of the home's 101 residents are displaced from their rooms, but they will stay in spare rooms at the home.

Residents seemed calm through it all and said staff could be thanked for providing great care under pressure.

"Everything worked so well. It was like nothing happened and we all had supper," Betty Craven said.

Thauvette-Chenier said she believes it could take about a month to repair all the damage in the home.