"Unfortunately, over time, the sun had reflected off the metal," he said, and like a magnifying glass, the concentrated heat sparked a fire in the surrounding wood and leaves, which had become tinder dry due to drought-like conditions.
The owner had no idea the metal sheeting could start something like this, said Concialdi, who recommended using non-reflective materials, like wire mesh, instead.
"It's very rare, but it does happen, like in this case."
Hot weather over the weekend fueled flames as they moved up mountain slopes, consuming chaparral and oak trees that had not burned in years, fire officials said.
At least 71 homes in the canyon were left without electrical power after the fire charred two utility poles Friday night, Cleveland National Forest officials said.
The fire was 80% contained by Monday afternoon, officials said, with more than 1,000 firefighters, five helicopters and four bulldozers still fighting the blaze.