PREFACE (OCTOBER 08, 2015): I made these insulated inner covers once and didn’t make them again because a piece of insulation over the inner cover in the winter position works just as well and requires no work other than cutting the insulation. I also use moisture quilts instead of hard insulation. See the updates at the bottom of this post for all the details.
Winters in St. John’s, Newfoundland, provide a messy mixture of rain, snow and high winds with irregular periods of freezing and thawing. Wrapping Langstroth honey bee hives with a Type 15 asphalt felt isn’t a bad idea. Neither is installing mouse-proof entrance reducers. Preventing condensation, though, is the top priority. A 1-inch thick piece of R5-rated hard insulation over the inner cover in the winter position will prevent condensation from building up inside the hive during the winter. We used a 1.5-inch thick piece of insulation during our first winter (because we couldn’t find anything else) up until the end of January. Then we had to switch to insulated inner hive covers because the regular inner covers don’t provide enough room for candy cakes and pollen patties. A shim lifting a regular inner cover up an inch or two would provide enough space. However, an all-in-one insulated inner hive cover might be more convenient. It requires moderate carpentry skills (which means we’ll probably go with the shims instead), and it’ll cost a little more, but here’s how we made them if anyone is interested. We’ve tested them, and they work.*
You will need a piece of lumber close to an inch thick and 2.5 to 3 inches inches high (to be cut into 20 and 15 inch long pieces). You will need some 1-inch thick R5-rated hard insulation (cut to fit inside the cover’s outer frame). You will need a thin sheet of wood or high-density fiberboard (also cut to fit inside the frame). You will need some short thin nails. You also will need some screws and maybe some carpenter’s glue.
The following instructions aren’t precise, but they don’t need to be. What you’re aiming for is a frame the same width and length as a regular super that will hold a piece of hard insulation about two inches above the top bars in the top brood box. The insulation prevents condensation build-up. The space beneath the insulation provides room for candy cakes, pollen patties — and the bees. Our bees clustered heavily at the top of the hives during the first winter, probably from running low on honey (see this video). At least 2 inches, maybe even 3 inches, of space would reduce the likelihood of the bees getting squished after the pollen patties and candy cakes are added. Without the extra space, the bees cling to the inner cover and get squished by the pollen and candy cakes when the cover is put back in place. That’s why the height of the frame can be anywhere from 2.5 to 3 inches. It depends on how much room you want to give the bees.
1) Cut the lumber into 15 and 20 inch pieces and screw them together to make a frame that will fit over your top brood box (see the above photo). The side pieces are 20 inches long. The end pieces are 15 inches long. The exact dimensions may vary depending on what kind of supers you have. We somehow managed to screw them together at more or less right angles so the frame fit right in line with the top of a super. But it was pretty rough. A T-square comes in handy.
2) Cut a piece of hard insulation so it fits snugly inside the frame.
The dimensions will vary. Ours turned out to be 38cm x 47cm, whatever that is in inches.
If the lumber is 3 inches high and the insulation is an inch thick, that should leave about 2 inches of space beneath the insulation (or in this photo, above the insulation). Our lumber was 2.5 inches high and the insulation was 1.5 inches thick. It left us with only an inch of space, which we discovered was barely enough room for candy cakes and high clustering bees. (We make the mistakes so you don’t have to.)
3) Cut your thin sheet or wood or high-density fiberboard to fit inside the frame, and place it right on top of the insulation. Brace the board in place with thin nails like this:
We drove the nails in at an angle, and then banged them down flat to hold the board in place. The board should fit a little loosely into the frame so you can see bits of the insulation through the cracks on the outer edges.
4) Cut a normal sized ventilation hole / top entrance at the front of each inner cover. Once the bees have been fed for the winter, the insulated inner cover is placed over the brood chamber to replace the regular inner cover. The outer cover is placed as usual on top of the insulated inner cover. And that’s it. The top entrance may not be sheltered by the outer cover, but our bees didn’t seem to mind.
For the less carpentry-inclined beekeepers, a simple piece of insulation over a regular inner cover like this will also work (show here without the top cover on):
But when it comes time to add any pollen patties or sugar cakes, you’ll need to use a shim to provide an extra inch or two of space.
* We tested the insulated inner covers and the simple piece of insulation over regular inner covers, and they both did a great job at preventing condensation over the winter. But note that we used 1.5-inch thick R-7.5 insulation, not 1-inch thick R5-rated insulation. I was told by a local beekeeper with over 20 years of experience that R5-rated insulation works just as well. We’re taking his word for it. But if you want to play it extra safe, use the higher rated insulation instead. We will update this post if we discover any problems with these designs.
UPDATE (August 09/11): These ventilator rims might work just as well as the insulated hive covers. I haven’t tested them in the winter yet, and I’m not sure if I’m willing to chance it. But if they did work just as well in the winter, I’d just keep them on all year and never bother with the insulated inner covers. I’ll get back to you.
UPDATE (August 11/11): The simple piece of insulation over the inner cover works perfectly. The only issue with that method and the insulated hive covers is that there’s not enough space for candy cakes or pollen patties that are added around late January or February. Therefore, I would use a two-inch rim (or eke) for the simple piece of insulation set up, which would also work for the insulated inner cover set up. But if I make any more of the insulated inner hive covers, I’ll simply use a taller piece lumber, one that’s at least 4 inches high. I’ll probably just use a 2-inch high rim, though, because it seems like the simplest solution. Then don’t forget to wrap your hives.
UPDATE (Oct. 18/11): Some beekeepers place the piece of insulation under the inner cover, not over the inner cover like we’ve demonstrated here. If you go that way, just make sure you still have an upper entrance for ventilation. Ventilation is key.
P.S.: Make sure to remove the insulated inner covers from the hives before spring. See Big Time Burr Comb for more info.
BIG UPDATE (Feb. 02/14): Moisture quilts can be made with a saw, a drill, a few other do-dads and minimal carpentry skills — and, for me, they’ve proven to be worth the effort (and they’re not too costly). I more or less made the moisture quilts by stapling window screen to the bottom my ventilator rims.
I made the switch from simple hard insulation over the inner cover to moisture quilts about a month ago because I noticed the insides of my hives were soaked (possibly because they were moved to an exceptionally foggy location this past year). A month later my hives are dry inside, dryer than I’ve ever seen them.
It’s still too early to make the call, but so far I’m very impressed, almost astonished at how well these things wick away all the moisture from inside the hives. Even after a month of rain, high winds and crazy temperature fluctuations, my hives are dry as a bone.
I held out on the moisture quilts until now because I was tired of always having to build something new for my hives (beekeeping isn’t the most affordable hobby for working class folk), but the moisture quilts, probably more than anything else I’ve built, seem to be worth the extra effort.
NOVEMBER 10, 2015: See Moisture Quilts vs Hard Insulation for an explanation and demonstration of both methods. And here’s a video that demonstrates how easy it is add a piece of hard insulation over the inner cover, essentially creating an insulated inner hive cover (taken from my Quick & Dirty Hive Preparations post):