Here’s the low down on exactly how we wrapped and prepared each of our four-month-old double-deep Langstroth hives for winter:
1) Built and installed the world’s simplest, cheapest mouse-proof entrance reducer and made sure to check the hive for mice beforehand.
2) Flipped the inner cover to the winter position (with the flat side facing up) and placed a piece of hard insulation over it. The insulation has a R-7.5 rating, whatever that is. Apparently, R-5 or above will keep the condensation from forming in the hive. It looks like this before the top cover is added: