A mother and two young children escaped their burning home near Lake Rotoma with the fire service needing to bring water from Ngongotaha to put it out.
Fire safety investigator Stuart Bootten said the fire started in the laundry attached to the back of the house and destroyed the room, a sleepout bedroom and toilet. Windows were also broken in the house.
The blaze happened about 6.50am today.
Being in a rural area, there was no access to water for the firefighters so a water tanker was used from Ngongotaha, he said.
He said the house would not be able to be used due to damage to the power meter on the back porch.
The occupant, who did not want to be named, said she heard the smoke alarm go off in the hallway before the living room alarm was triggered. They had had alarms installed in every room for about 10 years.
"The safety message has been reinforced here, the mother and her two young children were alerted by the smoke alarms," Mr Bootten said.
"This is a really good example of the owner going with what the fire service has said, smoke alarms in every bedroom, hallway and lounge and they were alerted in the early stages of the fire."
Mr Bootten praised the woman for having the presence of mind to close the door which isolated the fire and stopped it from spreading.
"Smoke alarms and sprinklers do save lives, this may have been one of those cases. The fire service always recommend a sprinkler service, especially in rural areas.
"Anyone rebuilding, we certainly encourage them to inquire into that, due to the fact of the time to get fire trucks to them." Sprinklers would have prevented the damage, he added.
The cause of the fire was still under investigation. Mr Bootten encouraged people to check their appliances.
He said two weeks ago a house fire in Mamaku was caused by a faulty washing machine.
"The preliminary investigation is looking at the washing machine and dryer and I encourage people to check the lint filter and even go online to Energy Safety Services appliance recall to check their appliances are not on the list and, if they are, to get them urgently serviced."