The fire mechanics are actually semi-realistic and one of the cooler bits of the game mechanics. Fires need draft (so air gets in), venting so smoke gets out (although this can be cheesed), and cover from rain and wind. A fire right next to your building benefits from 3-4 half walls around the base, and a roof suspended far enough above to let the smoke vent out. The roof can be a slanted section or peak section (your choice).

The partially ruined buildings you find with a narrow 2m channel down the center of the roof can have a fire at the end opposite the door (remove the center floorboards to expose the dirt) and no chimney, as that center channel is big enough to dissipate the smoke above your head. Just repair the damage and move in :)