A Northland family have lost all their possessions after a cat knocked over a candle, setting fire to their house.

Their barking dog alerted the family to the flames engulfing the house by State Highway 12 at Kaikohe last night.

Kaikohe volunteer fire officer Wiremu Matene said today that firefighters were called out about 8.30pm.

They arrived to find the rear of the building alight and the family of five running down the driveway.

The fire was put out, but smoke damage was extensive.

"They have pretty much lost everything," Mr Matene said.

The parents told him they had been waiting for Housing New Zealand to connect mains power to the property, and they had been using a generator, gas bottles and candles.

One of the children, who had had a bath, forgot to blow out a candle on leaving the bathroom, and a cat knocked it over.

There were smoke alarms in the house, but there were no batteries in them, Mr Matene said.

"Apparently, the dog alerted them to the fire by barking," he said.

"But if they had been asleep at 2am, they would have had little show because their smoke alarms weren't working."