Here in the Pacific Northwest, winters aren't nearly as cold as they are in other parts of the country, but rain is constant throughout the season, making condensation a real problem inside beehives. Condensation can form beneath the top or inner cover and drip down on the winter cluster, killing bees that otherwise may have well survived the winter.
To make moisture quilts, construct a frame to fit on top of your beehive. As you can see in these photos, you can use 1x3 boards, or even 1x2. Or you can even use a shallow honey super. Of, if you have a good table saw, you can rip a shallow honey super in half along its length and width, giving you two moisture quilt frames.
Drill ventilation holes in the frames, and over with #8 hardware cloth.
Stretch #10 or #8 hardware cloth over one side of the frame. I place the frame down on the hardware cloth, trace the inner dimensions using a marker, then cut it out, allowing an extra inch on all sides to be folded up and stapled to the inside of the frame.
Cut burlap to fit inside the frame. The burlap will keep the insulating layer contained and out of the hive supers.
Place the prepared frame on top of the hive. Fill with kiln-dried pine shavings - the kind you can usually get from a feed or pet store.
Place the top back on the beehive. You do not need to use the inner cover - your telescoping (or other) top will suffice.
With this installed, your bees will have a much better chance of surviving the winter. Any condensation that forms beneath the hive cover will drip onto the insulating layer of pine shavings. The ventilation holes will allow air circulation, letting the chips dry and preventing mold.