Ottawa Fire crews were called to the Riverside and Uplands area on Saturday around 10:30 p.m. after flames were spotted coming from the roof of a single family home.
When crews arrived at the home on Malhotra Court, the flames had spread to a neighbouring home.
It took close to two hours to get the blaze under control and fire crews remained on scene into the early morning hours on Sunday to monitor the hot spots.
No one was injured in the blaze.
Initial reports peg the damages at $650,000.
An Ottawa Fire investigator is looking into the cause.