my dad was welding in the garage and sparks caught a piece of cardboard on the floor behind him, he was to focused on the work to notice by the time he noticed the fire had spread to about the size where you need water to put it out, by the time he got water to the fire about half of the ceiling tiles and plastic light fixture covers had completely melted and the whole roof looked like honey being poured from 20 different containers
im glad our garage is separate from the house that couldve been a lot worse
no actual structural damage though, just the roofing and a shelf