Firefighters say that a deck fire at a Vancouver, Washington home started when reflected sunlight from a nearby window kindled a fire in a planter located on the deck. The fire didn't appear to be particularly destructive to the deck, but climbed up the siding and into the attic of the single-story home, causing about $160,000 in damage. Clark County Assistant Fire Marshal Richard Martin noted that this type of fire is not unheard of.
Insulated glass panels used in windows, sliders, and patio doors sometimes have a slight concavity, which is caused by a pressure difference between the outside air and the gases trapped between the inner and outer glass layers of the IG panel. Research has shown that - under certain conditions - when sunlight reflects off the glass, the concavity can focus the light and create hot spots with temperatures exceeding 200-degrees F, which can melt vinyl siding, cook decking, and - apparently - start fires in planters.