Loudoun Co. barn fire traced to ‘spontaneous combustion’ of mulch

Fire officials in Loudoun County, Virginia, are blaming the spontaneous combustion of mulch and potting soil for a fire that tore through a barn.

Crews were called to a farm on Lincoln Road in Purcellville just before 4:30 p.m. Tuesday, when a caller reported a large barn on fire. Firefighters arrived to find the barn engulfed in flames and smoke.

Hazardous materials units also responded to the scene due to flames encroaching on several propane tanks. Firefighters quickly brought the blaze under control but remained on scene for an extended period knocking down hot spots.



An investigation later traced the fire’s likely origin to what a news release described as a “spontaneous combustion” of mulch and potting soil from a flower box.

“Spontaneous combustion can happen when a decomposing, organic material such as mulch generates enough heat to ignite without an outside source,” Loudoun County Fire Chief Keith Johnson said.

“Because of this, a large or compacted area of mulch can create sufficient heat to spontaneously combust. Remember, in all cases, mulch fires are more likely to start when the weather is hot, and it has been dry for an extended period.”

Property damage was estimated at $542,000. No people or animals were injured.

According to the Loudoun County fire marshal, homes and business can minimize the risk of a mulch fire by:

  • Maintaining at least 18 inches of clearance between the edge of a mulch bed and flammable building materials such as vinyl siding and wooden decks.
  • Keeping landscaped mulch beds moist if possible.
  • Ensuring proper clearance from electric devices such as lights.
  • Using non-combustible materials for the first 18 inches around the base of a building with flammable siding, and around gas or electrical meters.
  • Using brick or non-combustible exterior siding for buildings or renovation projects.
  • Disposing of matches, cigarettes and cigars safely in a sand-filled metal or ceramic container, placed clear of a structure.

Alejandro Alvarez

Alejandro Alvarez joined WTOP as a digital journalist and editor in June 2018. He is a reporter and photographer focusing on politics, political activism and international affairs.

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