A house in Morton Street, Queanbeyan, was substantially damaged by fire on Sunday.
The fire began in a front bedroom but other parts of the house suffered smoke damage.
A Queanbeyan fire station officer said the damage could amount to $50,000, but it was not known how the fire began.
When the fire began, neighbour Emily Priest heard a window popping from her balcony a few doors away.
“We saw the smoke come up from what I thought was a chimney, then we heard all this popping,” she said.
“The fire was everywhere, the smoke looked like a tidal wave.”
The blaze spread quickly and the fire brigade took about 40 minutes to extinguish it, she said.
“We heard it was electrical, but they don’t know what happened yet,” she said. “The front bedroom looks ruined.”