The fire caused major smoke damage to the house, although actual fire damage was confined to a small part of the living room wall and ceiling. Last night, she stayed with her parents.
Mrs Birtles left home to go into town about 10.30am. Everything was all right then.
When she came home about 11.30am, as she turned into Taward St she saw white smoke pouring out from under the roof of her house.
The windows were black and she could not see inside, but managed to get in the back door and phone the Fire Service.
Philosophical about the damage, Mrs Birtles said: "You can't do much about it now."
There was no-one in the house at the time and Mrs Birtles had managed to find three of her four cats.
"There's no skeleton inside, so the other one must be around somewhere," she said.
Two units from the Oamaru Fire Brigade were sent to the fire, along with two police cars to control traffic.
It took about two hours for the fire to be extinguished. Efforts were complicated by loose fibre insulation in the roof which made it difficult to find what was smouldering.
While the fire was next to a log burner that was lit, Oamaru chief fire officer Gary Gibson was not certain what had caused it.
Mrs Birtles said fire was confined to a chair next to the log fire, the wall, ceiling and a ceiling fan.
A fire safety officer was to inspect the damage to see if the cause could be established.
