A woman had to be led to safety after flames took hold of the caravan parked on a driveway in Walsall.
Fire crews attended Bridge Road in Shelfield following calls about a blaze outside a property at 3.30am on Sunday.
The fire spread to the semi-detached property and melted window sills and gutters.
The caravan was destroyed in the blaze. The occupant was led out of her home and was given oxygen by emergency crews. Neighbours in the adjoining house were forced to leave their home.
It is understood police are treating the fire as arson.
Watch commander Steve Palmer, of Aldridge Fire Station, said: "This was a serious fire to a caravan that could have engulfed the house had we not responded so quickly.
"It did spread to the house and part of the windows and doors melted as result. The caravan was completely destroyed."
One neighbour, who did not want to be named, said: "I heard sirens and looked out my window.
"I could see lots of flames coming from the caravan. It was frightening."
Another neighbour, who did not want to be named, said she saw the fire crews arrive as well as the police.
"The flames were quite high," the woman said. "It looked a bad fire."