Turangi chief fire officer Tong Kingi said the investigator would try to determine what had started the fire, which was not being treated as suspicious.
"It appears it started in a bedroom and then spread throughout the house,'' Mr Kingi said.
"Neighbours ... saw large flames coming out of one of the windows.
"The house was fully involved on arrival.''
Mr Kingi said the single-storey timber home would need to be demolished.