Rachael Hutchen was at work when she received a call from her husband to say their two-storey home of the past four and a half years was on fire.

Luckily, no one was home at the time.

"It was a shock," Ms Hutchen said. "You always hear these things happening to other people but you don't expect to be in a meeting and get a call to say there's fire trucks at your house."

Ms Hutchen rushed home to find about half a dozen firetrucks and "lots of action" with crews working hard to extinguish the fire.

She said she felt "heartbreak" at what happened, but also relief that no one - especially her two young children - was home at the time.

"I'm just relieved everyone is okay," she said.

Ms Hutchen was particularly thankful for the June Long Weekend public holiday, because on any other Monday her husband would have been at work on night shift - meaning he normally would have been at home asleep at the time of Tuesday's fire.

She said the full extent of the damage was not known at this early stage.

"From the outside it doesn't look too bad, but from what we've been told it sounds pretty bad on the inside," she said.

The family will stay with friends until they hear back from the insurers about what the next step is.

"I'm in survival mode now," Ms Hutchen said on Tuesday afternoon. "It's out of our control.

"I'm now starting to think about getting the kids from school and going to Kmart to buy pyjamas. And we have a two year old, so sorting out nappies."

Fire and Rescue NSW duty commander Inspector Michael Woodward said the cause of the fire was undetermined but was being investigated.

"There is nothing to indicate it was deliberate," Inspector Woodward said.

Inspector Woodward said responding crews got the fire under control very quickly and managed to contain it to the area of origin.