A neighbour, Wayne Schmelz, raised the alarm after hearing what he described as a "pop" sound and looked up to see flames a metre high through the windows of the Norman Tce house.
Crews from from Wanaka, one from Luggate and Lake Hawea, and the command unit from Alexandra attended.Wanaka volunteer deputy fire chief Tony Wellman said the fire was “well involved” by the time crews arrived.
Mr Wellman said he thought it unlikely the house could be saved as it was “structurally very damaged”.
It had been an old timber home and the wood was very dry which would have contributed to the speed of the fire, he said.
Fire investigators are expected at the scene tomorrow morning.