Detective Beck told the Bay of Plenty Times yesterday that nobody had seen or heard anything to help the investigation.
"It would be nice to know if there was someone out there that had any knowledge."
Greerton Fire Service Station Officer Richard Moreland said the alarm was raised at 4.45am by a passing motorist and the house was "totally involved" when they arrived a few minutes later.
Firefighters hit it with a low-pressure hose, delivering enough water to have the blaze under control within 10 minutes. Two tankers were used to supply water to the fire, with one filling up at a hydrant near the entrance to The Lakes while the other was emptying out.
A small hose dampened down nearby hay bales, although the prevailing wind was away from the bales and a stand-alone garage, which was not damaged.
The last crew was still there at 11am, turning over debris on the floor of the house to assist fire cause investigators.
Lakes sales manager Simon Maxwell said the house was used as an office before construction of the bypass and contained only out-of-date sales brochures.
"It is inconvenient but there is not a lot we can do about it. It is just something we will have to work through."
Mr Maxwell said all the company's assets were insured, so he assumed the farmhouse was covered as well.
Carrus Corporation, the new owner of The Lakes, was planning to call tenders to sell and relocate the house and adjoining garage.
The two buildings stood in the way of one of the next stages of The Lakes.
Meanwhile, police investigations are continuing into the fire that destroyed a two-storey house in Ohauiti Rd last week.
The 5.30am fire on August 15 was being treated as a suspected arson. No one was at home at the time and the Bay of Plenty Times has been told by one neighbour that the occupants had moved out about a week earlier.
The property is at the centre of a court restraining order, which was granted last month under the proceeds of crime law.
Tauranga fire safety officer Ken McKeagg confirmed that an electrical fault, electrical appliance malfunction and accidental ignition had been ruled out.