The two adults and three children have been renting the house for about three years. They are believed to be staying with family and friends.
Mr Beer said a member of the family discovered a fire in one of the bedrooms and raised the alarm.
The family unsuccessfully tried to douse the flames using a garden hose.
Mr Beer said everything was destroyed, including a car that was parked in a garage beside the house. It's understood the family had contents insurance.
Mr Beer and fellow fire investigator Roy Brickell are investigating the cause of the blaze.
He said it was a good time to remind people to check their smoke alarms and to develop an escape plan.
"A remainder to landlords to ensure they have working smoke alarms because it's a rule under the Tenancy Act."
He said the house had a smoke alarm but he didn't know whether it was working at the time.
Fire and Emergency NZ has constantly reminded people of the importance of installing smoke alarms, having better knowledge of home escape planning, having a safe meeting place and calling 111 early.
It recommends long-life photoelectric smoke alarms in every living area, hallway and bedroom.
Occupants may have only one or two minutes from the sounding of the smoke alarm to when their lives are seriously threatened by fire or smoke.
"That's why it's essential to have an escape plan in place, to practise it regularly, and to know how to get to safety quickly," Mr Beer said.
