I like the idea of a migratory top for my long langstroth. I use four flat boards, end to end to cover it. I can remove any of the four and expose only a quarter of the hive at a time. There is 3/8 inch beespace between the top of the frames and the boards I use as a top. Here is the problem. I need a better coverall for the hive.
1. As you can see in the picture, my plastic rain cover stretches and protracts in the heat/cold of the day, shifting it. Sometimes in just a few days, expposing it to water.
2. I could use NO coverall, just the four migratory boards, end to end in a row covering the hive. But then with propolis, the boards never fit back snuggly, leaving gaps and exposing the hive to rain dripping on the bees from above.
3. I could use a big solid cover, hinged on the long end like the top of a coffin. Perhaps a flat long board. I want to avoid a telescopic top with removable top bars underneath. I live in small hive beetle country, and hate to think of beetles retreating safely up into an attic.
4. I could use a long piece of tin over the top, in place of the plastic. But if it is corogated tin, the bricks on top will have a hard time supplying the pressure needed to keep all four top boards down flat. If the tin is long and flat, then I have a hot piece of metal transferring heat into the hive. But maybe that is the best way, and paint it white.