The facades of the buildings burned in Valencia were covered with flammable material: "The polyurethane turned it into a chimney" The most serious fire that the city has ever suffered has caused columns of smoke visible for kilometers, while the smell of burning has spread throughout all the neighborhoods. "It is the reason why the fire has spread so quickly," insists Juan Antonio de Diego, an expert insurance appraiser and expert in the structure of the building that this Thursday was devoured by flames.