I had a friend whose law office burned several years ago. Now, this was a building fire, - the building was still partially standing, although too far gone to be rebuilt. Firefighters also quickly got the blaze under control, so we're talking about something different than a forest fire.
But still, I was amazed at how well a common filing cabinet protected his files. These were the more expensive filing cabinets, the ones with multiple rollers on the drawers, not the $35 ones from Walmart, but they were still not the even more expensive fire proof filing cabinets. I think for most of us, who only have to fear a normal building fire, that a good filing cabinet, kept closed, may be sufficient protection.