"I had gone for a walk and came back an hour later and basically the whole Fire Service was here," said Mrs Hopman.
"What hasn't been destroyed has been totally ruined by smoke ... half the house is pretty munted."
She said the fire had started somewhere in the back of the house.
Five teenagers were staying at the house at the time.
Mr Hopman had gone to the shops and received a phone call from a friend of one of his teenage children to say the house was on fire.
"Steve had said he thought he could smell something odd - but he thought it was one of the kids' shoes," Mrs Hopman said.
She said fire crews were "absolutely brilliant" but were still not sure over what caused the fire.
"If it had been at night it would have been a whole different scenario."
Masterton Fire Station officer Mike Cornford said the fire was "well involved" by the time firefighters arrived at the house.
"The house was totally smoke logged and there [were] flames in three rooms," he said.
Three fire engines were sent to the house fire and crews took around 20 minutes to get the better of the blaze.
Firefighters had stayed at the house for several hours to make sure it was completely out and to dampen down.
Mr Cornford said the fire was not suspicious, but he was still not sure what had caused it when spoken to yesterday.
The house had no workable smoke alarms and Mr Cornford said the family were "quite lucky" the blaze had broken out during the daylight hours.
"They were lucky it was in the afternoon and not in the middle of the night," he said.
The Greytown Fire Brigade was called to Loasby Place on Saturday to help a homeowner extinguish smouldering firewood near a fireplace.
