Fire control rules are somewhat different between the US and Europe. In Germany, such a system would be fine. Depending on the door even encouraged. A large pa

Fire control rules are somewhat different between the US and Europe. In Germany, such a system would be fine. Depending on the door even encouraged. A large part of German Fire Code is to prevent the spread of the fire and contain it in the rooms where it started for as long as feasible. The lowest rating a fire location can have is E30, meaning the fire takes 30 minutes to "break out" and spread further. The building owners likely also benefit from grandfathering (ie, special building fire code, which depends on federal state in germany). It also depends on the fire load, ie, how much flammable material the house contains. A concrete or stone house that contains only flammable material as part of furniture isn't a huge fire load and you don't need heavy doors to prevent fire from spreading out of a single flat, a normal door will likely already prevent spread.