I have a notch on the under/bottom lip of my inner covers on all my hives. I leave my screen bottom boards open...though it took me a long time to get comfortable with this practice. I like to take a 1" piece of blue insulation board and set it on top of the inner cover to reduce the likelihood of condensation on the underside of the inner cover.
I think this works well for winter ventilation.
More and more, I've gone to these sheets of blue insulation board as year-round outer covers. A 4x8 sheet $19.99 at Lowes and I can cut out ten covers from each sheet. So far I have some that are three years old. They do take several bricks to hold them down.
I have six beemax hives. I made my own inner covers for them to account for inverted buckets for feeding. And I notched these homemade covers on the underside as well. I can't say I notice any difference in my bees, however, those big, black "bull" ants like to make tunnels in the beemax hives.
This works for me. I know most like to have that notch on top.
Grant
Jackson, MO
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