How did you manage in this, and was it with some previous version? They oughta warn you few times first, then ask you to leave, and proceed with almost an immediate attack if you continue with breaches. I did a quick try and managed to start two fires before getting attacked.
I covered a house completely with branches and slender tree trunks (put them over the wall tiles) and then sneakily started a big fire on an adjacent tile. Then after getting shouted at I just waited and watched the fire spread and eventually burn the whole house down. But yeah, it was a long time ago on an older version, and now that I tried it on the current version I couldn't get the fire to spread at all. Has there been changes to how that works?