Firefighters were called to Penelewey, Feock, yesterday afternoon after a report of a fire in a summerhouse.
Crews from Truro and Falmouth attended the blaze just after 1pm and crews used one hosereel and one main jet, two breathing apparatus a thermal image camera and a hydrant.
An ambulance was requested for one casualty who was suffering slight smoke inhalation.
One gas cylinder was involved and was cooled and then safely removed from the building.
The cause is believed to be accidental.