At 12:45hrs. GSFR Truck 39, Tanker 39 & Rescue 39 was dispatched as part of the 1st Alarm Outbuilding Assignment. Chief 35 checked up within seconds after dispatch reporting a Working Fire and requested 4 additional tankers to the scene. Engine 35-1 arrived and deployed a 2 ½ with Blitz Fire and (2) 1 ¾ lines to begin attacking the fire. Tanker 35 supplied Engine 35-1 with water. Truck 39 arrived and setup aerial operations along with Truck 31. Truck 39 popped the roof. Tanker 39 assisted in the tanker shuttle. Tanker 29 setup a fill site at the end of the driveway. Engine 29-1 went to Schaeffer School Road to setup a Fill site. Air 61 filled air cylinders. Rescue 39 arrived and had the RIT. The fire was placed under control at 13:18hrs. There were no injuries reported. Crews Cleared at 13:49hrs. The cause of the fire was a woodstove.