On arrival to the Covala Court house, firefighters found the two storey brick house fully engulfed by fire.
Up to 30 firefighters on scene were able to control the fire within an hour but the house was completely destroyed.
The top storey of the house collapsed during the fire attack.
The family of two parents and two boys survived the fire uninjured.
Fire investigators have returned to the scene today to try and determine a cause but the fire is not suspicious.
CFA crews remained on scene blacking out until after midnight.
Six CFA trucks from Eltham, Diamond Creek and Bayswater attended the incident.