"It was extremely dangerous sending crew in there," Swarbrick said.
With nearby buildings protected, a direct attack on the fire was initiated including checking to make sure no one was inside.
"The initial report from some bystanders was they thought someone was inside because they could hear voices.
"On investigation it was found there was nobody inside, thank goodness."
The callout involved two Paraparaumu fire trucks and a support vehicle, two fire trucks from Waikanae and an aerial platform from Wellington City to help remove the roofing iron and extinguish the fire completely.
"The last appliance left at about 6.50am."
Swarbrick said the fire was being treated as suspicious.
"We had a fire investigator there and police were notified and will be doing their own investigation as well."
The house was one of nine that are being demolished to make way for a 78-townhouse development on 10,000sq m of land.
The site is expected to be cleared by the end of the month.