Fire and Emergency New Zealand fire investigator Scott Cameron said the occupant did everything right.
"The smoke detectors activated, that’s what alerted the occupant and they were able to get out safe and call the fire service," he said.
Six appliances from Invercargill, Kingswell and Bluff as well as additional support vehicles attended the fire which razed the 1950s-built home.
While the fire was under control within an hour, it took attending crews more than five hours to fully extinguish the blaze in the four-bedroom house.
The Bluff water supply was gravity fed and the downhill flow from the street to the back-section property provided additional water pressure to the hose crews.
Mr Cameron said it appeared the fire had started in the roof space.
"You can see from ... the colourisation on the roof — that’s pretty extreme heat that’s gone through that wee place."
It had been a difficult fire to battle because crews were unable to douse the seat of the blaze and had to work from outside the house. Usually, crews would pull off the roofing iron, but "because it’s an unstable roof, we can’t commit people".
He expected the house would be a total loss.
"It’s pretty unfortunate. Fires that devastating, they lose everything."
Mr Cameron said while his investigations were still in the preliminary stages, it was likely the cause of the fire was accidental.
Neighbouring properties were unaffected.
"The brigade acted pretty swiftly and contained everything."
The Otago Daily Times was unable to contact the occupant of the house.
