Around 40 firefighters attended the blaze at Gay Street Lane, just after 12.30pm.
Although the fire is now out, firefighters remain on the scene damping down affected areas, while the A29 between Adversane and Pulborough remained closed until 4pm.
The first crews arrived at the property within minutes, and were faced with a developing fire in the garage and roof space of the two-storey house.
Assistance from additional fire crews was immediately requested.
Firefighters wearing breathing apparatus tackled the fire and quickly prevented further spread, using four main jets and two high pressure hose reels.
Two small gas cylinders, involved in the fire, were removed and made safe.
The blaze, which is believed to have started accidentally in the garage, is now out, but firefighters remain on the scene damping-down affected areas.
Support and assistance for the occupiers of the property is being provided by the Red Cross Fire and Emergency Support Service.