One crew from Amersham, Aylesbury, Berkhamsted and Hemel Hempstead attended a fire involving an outbuilding containing fuel pellets.
Firefighters used two sets of breathing apparatus, one hose reel jet, a thermal imaging camera and a telehandler to extinguish the fire.
Approximately 25% of the barn was damaged.
Crews remained on site to remove the pellets and damp down the area.