James Ponsford, a recent arrival in Wanaka from Nelson, escaped with minor burns to his hands and a leg after waking up just before 3am to find himself on fire.
He had been sleeping on a bed next to a woodburner in the lounge at 5 Glengyle Way. There was no working battery in the smoke alarm.
Ms Ponsford woke his flatmates, Elliot Sims, Grace Caudwell and Jade Higham, and they escaped the rented house, with their pet basset hound cross, Foley, and called emergency services.
"He was very, very lucky .. I believe if he hadn't woken when he did, another two or three minutes and we would have been dealing with a fatality," Mr Cahill said.
The fire spread rapidly through the iron and wood-clad home.
Flames were leaping from the windows by the time the first Wanaka volunteer fire brigade member, neighbour Steve Walsh, arrived on the scene.
Mr Sims said the flatmates, all aged in their 20s, had received offers of help "left, right and centre" and were grateful for the support.
Mr Ponsford's injuries were "nothing too major" and he would be fine, Mr Sims said.
"If he hadn't got burned, he wouldn't have woken up," Mr Sims said.
The flatmates had lost their car keys, wallets and many other possessions in the blaze but hoped to salvage some of their gear from the less damaged bedrooms.
Mr Sims and and his fiancee Ms Caudwell lost presents received recently at their engagement party in Auckland and had not been insured.
"We've got each other. That's what counts," Mr Sims said.
The house owner, a friend of the flatmates, was insured and is in Japan.
They had informed him of the fire, Mr Sims said.
Mr Cahill inspected the ruined house yesterday and would report to police, the New Zealand Fire Service and other parties.
He believed the fire started alongside the fireplace, near where a woodbox containing wood and paper was stored.
"The smoke alarm was installed and I was told the battery had died and they hadn't replaced it," Mr Cahill said.
"I can't emphasise enough the need to have a workable smoke alarm, maintained throughout the year, and kept operative," he said.
"It's quite possible that it [the fire] was a result of items that had been placed on top of the fireplace ... People should refrain from putting clothes or placing items on top of any fire.
"The rule of thumb is: at least 1m away.
"Even the location of his bed is far too close to be considered safe."
The Wanaka brigade sent both its fire engines and its rescue van to the fire.
The volunteer firefighters worked in pouring rain until about 5.45am to extinguish the blaze, search the house and dampen down the hot spots.
Acting fire chief, Bruno Galloway, reinforced the safety message.
"We had a bit of a campaign and went round and installed smoke alarms. We haven't done any recently but we will do it if people ring us up," he said.
Wanaka police and St John Ambulance also attended.
