Launceston detectives will begin investigating the Rosetta Place fire this morning after the Tasmania Fire Service ruled that it was arson. 

The fire  followed a period of sustained targeting of the home and its occupant, The Examiner  understands. 

The fire began about 10pm and gutted the one-storey property, which is now an asbestos hazard.

A man was home but escaped without injury.  

Firefighters knocked the fire out in less than  30 minutes. 

Vandals have previously pulled down the property's fences, set fire to a back door and smashed windows. 

This financial year has seen 11 deliberately lit structure fires in the North. Eight have been homes, followed by a recreational property and a commercial address.

The remaining fire was listed as ``other''.

Records show there have been 34 deliberately lit structure fires in the South in the past six months, including 22 homes.

There have been five deliberately lit house fires in the North-West and three other torched buildings in that time.

Liberal  police spokeswoman Elise Archer said the best deterrent to arson was more police on the beat. 

``When Labor cut police numbers it gave the green light to criminals -  that's why we have seen a spike in serious crimes and antisocial behaviour,'' she said. 

A  spokeswoman said Tasmania Police  employed ``a range of strategies year-round to deter and detect arson''.

``Like any crime, arson is investigated and offenders are  brought before the courts,'' she said. 

``Tasmania Police and Housing Tasmania also work very closely together.''