A man was asleep as his house burned only escaped after being woken by the sound of his door breaking.
Firefighters were called to the house in England Street in the Auckland suburb of Freemans Bay just before 11am.
Five flatmates share the single-storey house, and four were at work. However, one was asleep and was awoken by the heat and flames breaking his door.
He tried to fight the flames with a garden hose before firefighters arrived.
A firefighter said it was suspected a cigarette could have sparked the blaze.