Firefighters were called to the house on Bicentennial Drive at about 2pm, following several triple zero calls from neighbours.

Owner John Osmialowski, who has lived in the area for 24 years, was dealing with the disaster on Tuesday in the traditional Australian way - with a beer in his hand.

His 12-year-old son was the only one home at the time of the blaze, but couldn't call emergency services as phone lines were down.

Mr Osmialowski said his son tried to put it out himself, with the help of two Queanbeyan council workers who were in the area, but it spread too quickly.

He said he didn't know what was left of their belongings as he and his family would not be allowed back in until at least Wednesday.

"The house is not the most important thing, it's everything inside, everything we didn't have a chance to get out. The photos and the wedding photos and all that sort of stuff. That's the most important stuff to me," he said.

"The house can be rebuilt, it's everything inside that counts."

Mr Osmialowski said he had been at work when his neighbour phoned him to tell him about the fire.

"I thought he was joking and I said don't be silly and he said, 'No, get home now'," he said.

He said his son heard a bang before the fire began.

His neighbour Wayne Cochrane was one of the first people to see the fire.

"The back veranda I saw going up then I heard a noise, sound like hail on the roof. I ran in and called triple zero [before] I came back and made sure [John's] son was alright," Mr Cochrane said.

NSW and ACT firefighters attended the scene, including two fire appliances from the ACT as well as an aerial appliance and a breathing apparatus van.

NSW Fire and Rescue Queanbeyan station officer Mark Beachcroft said firefighters found the house well alight when they arrived and it took them 30 minutes to bring it under control.

"Although when we first arrived the fire was fairly fierce, with flames coming out of the building, we covered the exposures pretty quickly," he said.

He estimated the damage to be worth hundreds of thousands of dollars, saying up to 90 per cent of the house had been damaged, and there was no danger to surrounding properties.

Mr Beachcroft said firefighters still still haven't determined the cause of the fire and the investigation was ongoing.