Shoalhaven Police are investigating after a house at Mollymook was extensively damaged by fire on September 5.
Shortly after 6am emergency services were alerted to the fire in the single storey brick home in Ocean Street.
Fire and Rescue NSW and several Rural Fire Service crews attended the blaze, which took several hours to extinguish.
Police said it is believed the fire started in the garage of the unoccupied home and quickly spread throughout the property.
Examinations of the scene revealed the circumstances of the fire appear to be suspicious.
Shoalhaven detectives are investigating the blaze.
Anyone with information is asked to contact Nowra Detectives on 4421 96989 or Crime Stoppers on 1800 333 000.