Tuesday’s blaze at a home on Emerald street north in Hamilton caused over half a million dollars in damage.
Provincial investigators were called in because of the high value loss but the cause has now been ruled accidental.
Two fire fighters had to be evacuated from a top window, they were sent to hospital for smoke inhalation. They have since been released.
Three units were damaged, the main house where investigators believe the fire began, a home on Wilson, and a three storey house to the north.
The estimated cost of damage to the three properties is $600,000.