Germantown firefighters were called to fire at a Maple Road shop building on Feb. 20.
Crews were dispatched at 6:41 p.m. when a passerby called the dispatch center to report a large building behind a house on fire.
Germantown units arrived at 6:46 p.m. and found a 100- by 50-foot metal building with fire involving 50 percent of the structure. The building, which housed a sheet metal shop, had a lightweight truss roof.
Firefighters from Engine 62 deployed a 2 1/2-inch and worked with Engine 64 to make entry to the building.
Chief Gary Weiss said crews were withdrawn when lightweight trusses started failing and had the potential for roof collapse.
The fire was placed under control within 45 minutes.
The owner said he used coal from the wood burning stove to fill some gaps in the metal wall at the base of the cement pad. The ashes were still hot and ignited the inside wall before spreading through the structure.
