I have some langs and this year tried one KTH. Next year I would like to try a Waare, which I already have built. How do you know when to add another box on the bottom if you don't open the hive to see what's been built. In my experience, leaving to much space in a hive is an invitation to wax moths so I don't want to add one to early, or to late and cause them to swarm. If you don't look into the hive, what's the magic sign?