An over-heated lawn mower started a fire which caused significant damage to a Kambah home earlier today.

ACT Fire & Rescue were called to the scene in Springbett Street, where they found the home well alight just after midday.
Multiple crews extinguished the blaze, which caused an estimated $400,000 of damage to the unoccupied home.

ACT Fire & Rescue has confirmed the fire started in a detached double garage before spreading to the roof space of the house.

Fire crews are now ventilating the property.