I have 1 hive with a 10 frame deep. When the hive was last inspected about 5 days ago there were still 4 completely empty frames. I am feeding the bees due to the dearth and have noticed this week that there are lots of bees up in the deep with the feeding board. The bees are very busy building burr comb and sealing up the edges with propolis.
Is there a rule of thumb for adding another 10 frame deep? I'm wondering if the bees want to expand up rather than out.