Wood-burners kept me employed for many years. Part of what my company did was investigation of structure fires. And we could always count on a steady business in the winter months. Most improperly installed. Some just lack of cleaning. Many caught fire 15-20 years after installation because of lack of proper clearance to combustibles. The years of heat would slowly lower the ignition point of the hidden wall framing and then it would just take one more fire to ignite the whole thing.
"Never had a problem until yesterday!" was the usual statement from the owner. I don't even allow candles to be burned in the house. But obviously I'm slightly biased
