The Four Roads, St Philip property owned by husband and wife Troy and Sonia Harper was also occupied by relative Rukiya Clarke.
The family lost all their possessions in the fire which started just after 11 o'clock in the morning.
A distraught Troy said: "No one was home at the time. I got the call while on the road, I was hoping at least to save some items, but all is gone."
A team of five officers and two fire tenders from the St John and Worthing fire staions responded to the blaze. (Picture by Glen Hinkson.)