NSW Fire and Rescue and Rural Fire Service crews battled a blaze at a two-storey house at Bundeena on Monday.
They said that no one was inside the two-storey property in Baker Street, near Eric Street but the ground floor was damaged significantly and there was heat and water damage to the second floor.
NSW Fire and Rescue crews from Bundeena and Sutherland went to the scene and were assisted by Rural Fire Services from Maianbar and Bundeena.
Police confirmed that they were called at 3.30pm to a house fire in Baker Street, Bundeena.
There were reports at first that a man had been rescued but were not confirmed.
The fire was reported to be out about 4.40pm.
Ambulance NSW said a male in his man, 37, was treated for minor burns to his lower legs.
He remains in St George Hospital in a stable condition.
All occupants were accounted for.