Harwood property owner Lenore White called 111 about the fire in a spare room at 9.24am yesterday.
Minutes earlier, her husband Donald had rushed outside to battle the fire with a garden hose after ''something blew''.
In a dressing gown, Mrs White stood on the street as she watched the home the couple built almost three decades ago, engulfed in flames.
''I took nothing out of the house at all. We have lost 99.9%.
''I own a dressing gown and a cellphone ... we don't even have a pair of shoes between us.''
She was grateful to see firefighters who arrived at the property within minutes of the call.
Greg Dixon, of the Portobello volunteer firefighters, said the house was well alight when they arrived. Several Dunedin appliances and a water tank attended.
The fire was believed to have started by a sunbed, and would form part of a fire investigation to be carried out today, he said.
In an electrical fire, people were urged to turn off the property's main electrical switch, rather than the electrical appliance, he said.
The couple was thankful three of their cats had been found, with one unaccounted for yesterday afternoon.
''It is one of those things you don't think will ever happen to you,'' Mrs White said.
They now plan to live on site in a sleepout while the insured home is rebuilt.
The aftermath was made easier by support from the Harwood community, she said.
''I have superb neighbours. This is the best place to live in the world.''
Water for their sleepout was expected to be connected today, while an electrician visited yesterday to supply electricity via a neighbour's property.
Mrs White said her walking frame also went up in the blaze and in lieu of any potential donations she hoped people would support the Dunedin physio pool, which is set to close this year.
