>>A beekeeper who is very big top entrances propagandist here suggests top entrances to be 3.5cm diameter. I don't like drilling holes in my deeps. I place a ~1/4" (0.65 cm) dia stick under the top insulating newspaper. The stick extends from the inner cover hole to the edge of the inner cover. I find that the moist air flows out of the hive well. I don't see mildew or mold inside the hive. The newspaper absorbs a little moisture along the stick but this does not compromise its insulating value. I do have drilled holes in some of my medium honey supers to help provide an airflow in the summer months. >>I understand that slatted bottoms have some other adventages but I didn't unify my hives, it is maybe not too much serious of me. I've read/heard slatted racks reduce swarming but I have not seen any comparisons with regular colonies. Waldemar -- Visit www.honeybeeworld.com/bee-l for rules, FAQ and other info ---