Crews were alerted to the blaze, in Dewar St in Lake Hayes Estate, about 7.15pm, a Fire and Emergency New Zealand spokesman said.
They arrived to find one property "well involved" and the blaze spreading to a neighbouring property.
By 7.50pm the fire had been mostly extinguished and crews were damping down hotspots, the spokesman said.
It was thought no-one was in either property, and there were no reports of any injuries.
Police and ambulance also attended.
A fire investigator would be examining the scene.