Multiple fire crews were called to Shelby Road, Durrington on Wednesday, September 18 to deal with the fire.
A spokesperson for West Sussex Fire & Rescue Service confirmed that there were no casualties with crews leaving just before 6pm.
The spokesperson said: "At 4.21pm we responded to a fire at Shelby Road, Durrington.
"Joint Fire Control sent three fire engines from Worthing and a fire engine from East Preston to the scene.
"Upon arrival crews were confronted with a fire involving one outbuilding which had spread to the property.
"Firefighters wearing breathing apparatus used hose reels, jets and a thermal imaging camera to extinguish the fire.
"Fortunately there were no casualties and the fire was of accidental ignition.
"Crews left the scene at 5.40pm."