Wood Mulches Played Role In Threatening Homes During Glass Fire
Volunteer firefighter Steven Burgess told the San Francisco Chronicle that he noticed a pattern when the Glass Fire erupted in Napa County. Burgess found that many of the homes threatened by the fire had wood chips and plant-based mulches on fire outside the home.
“Every single wildland fire I have been on, where structures were involved, usually involved a problem with landscaping,” Burgess told the Chronicle, adding that it’s usually wood chips or other mulches.
“We see it all the time,” wildfire and hazard mitigation specialist Todd Lando said. “In every single major fire, we see wood chips in gardens ignite.”
Flammable materials such as wood chips are not allowed to be used within 100 feet of a house, according to Cal Fire, but enforcement is rare, according to the Chronicle.
“I think it’s important to remember that defensible space is the law in California. Virtually every jurisdiction has adopted some version of it,” Lando said. “But it’s really not a law enforcement issue in the traditional sense. It’s difficult for fire departments to enforce this because they can’t write a ticket.
A 2011 University of Nevada and University of California study found that every plant-based mulch it tested was combustible in windy, dry, hot conditions. The study found that a mixture of redwood cedar, pine needles and shredded rubber had the highest average rate of fire spread.
FireSafe Marin’s Richard Shortall said fires can be started when embers are blown into mulches.
“The next thing you know, the house has caught on fire because of fine wood mulches next to the home,” Shortall said.
Bee Green Recycling & Supply’s president Joshua Fookes suggested an ornamental rock mulch layer as an alternative to wood chips and mulches.
“The key is to cover the soil with enough material to prevent weed growth. Smaller gravels (pea gravel, Yuba stone, Mexican beach pebbles) are easier to clean leaves and other wind-blown debris from,” he said.
Lando and Shortall said gravel is a good, fireproof alternative to mulch for retaining soil moisture.
The Glass Fire burned 67,484 acres in Napa and Sonoma counties, destorying 1,555 buildings. The cause of the fire is still under investigation. A PG&E transmission line runs through the general location of the fire’s ignition point, and smaller utility lines were down after the fire in the general area as well. California law holds utilities liable for any property damage caused by any fires the utilities cause.