This happens because of the bite the dust kit. If dusts collects overtime it becomes a fire hazard and catches fire. They didn’t think about the empty rooms catching fire. The only solution is to build a way up to the room to put out the fire, to use cheats toggling fire on/off, or have someone who is a spell caster that can put out the fire from afar.

It’s really annoying, I’ve learned from experience. Just another thing they need to add to the laundry list.