Fire risk management officer for Central and North Otago Stuart Ide said Saturday’s blaze in the upmarket golf resort neighbourhood of Jacks Point was "most likely" caused by the disposal of hot ashes.
"From what I understand, they put the ashes into a plastic bag and put water on them," he said.
"They just probably didn’t put enough water on them."
The embers appear to have burnt through the side of the bag.
"There was a slight breeze, sufficient for the embers to blow around, probably catch hold of some fine combustibles like leaves.
"Then it’s spread up the side of the building."
If insurance company investigators, on scene yesterday, reach the same conclusion, the fire will be formally marked down as the 12th in Otago caused by the disposal of hot ashes since last July.
It would be the second in Queenstown in five weeks.
"It’s accidental but it’s a concern."
It is understood the property’s owners live in Singapore and rent it out through website Airbnb.
On Saturday, as fire crews dampened down and checked for hot spots, a group of five Asian people arrived at the property.
They were spoken to by police and then shown to the property.
Mr Ide said the Fire Service circulated safety leaflets to rental agencies that managed flats but that could be extended.
"We’ll certainly be looking at that as a way to educate and inform people.
"Because no matter how much money we put into advertising and promoting safety with fires, if you’re not in the country, you’re not going to see it."
Mr Ide said one of the problems could be the language barrier.
"Not everyone speaks English, so we may have to go a pictorial way.
"Mr Ide said there was extensive damage to the house.
"Smoke and fire damage up into the roof.
"All the electrical cables have been damaged as well, because it was right next to the main electrical feed into the house."
More than 30 firefighters from Frankton, Queenstown and Arrowtown were called to the blaze in Rannoch Dr shortly before 3pm.
Three breathing apparatus teams with low-pressure delivery fought the fire from the outside and inside.
Firefighters remained on scene until about 7pm.
Mr Ide added: "Safe disposal of ashes is extremely important because when they’re put outside, they spread up the outside and people inside, even if they have smoke alarms, are not aware they’ve got a major fire occurring."
He also reiterated the Fire Service’s safety heater-metre rule during the current cold snap — always always keep furniture, curtains, clothes and children at least 1m away from heaters and fireplaces, and do not cover appliances with anything, including drying clothes.
