Moisture Quilts vs Hard Insulation

I’m a true believer in moisture quilts as the best overall ventilation and moisture reduction aid for Langstroth hives in the winter. I’m a true believer because I’ve seen soaking wet hives become dry as a bone within a week of having moisture quilts installed.

An emergency moisture quilt that saved this colony. (January, 2014.)

An emergency moisture quilt that saved this colony. (January, 2014.)

Empty moisture quilts are excellent ventilation aids in the high heat of summer too, allowing the bees to regulate the temperature of the brood nest with less fanning and to cure honey sooner. Moisture quilts are also really cheap and easy to make. Everybody wins.

I’ve used hard insulation over the inner cover to reduce condensation inside my hives too. It worked well enough to get all of my colonies through at least two long, snowy, wet winters in St. John’s, Newfoundland. I always found some condensation inside the hives, but nothing that seemed to hurt the bees. The hard insulation method didn’t fail me until I moved my bees to a community called Logy Bay, one of the foggiest places on the island of Newfoundland.

And that’s when all of my colonies (I think I had eight at the time) nearly perished from condensation soaking through every frame of their hives. I opened the hives one day and it was as if someone had sprayed the bees with a hose. Everything was dripping wet.

A soaking wet hive in Logy Bay, Newfoundland.  The newspaper is soaked.  Most of the dry sugar (that white stuff) has dissolved away from all the moisture. (January 15, 2014.)

A soaking wet hive in Logy Bay, Newfoundland, in desperate need of a moisture quilt. The newspaper is soaked. Most of the dry sugar (that white stuff) has dissolved away from all the moisture. Yeah, it’s bad. (January 15, 2014.)

I immediately converted some ventilation rims to moisture quilts by stapling screen underneath them. It wasn’t pretty or neat but it did the job. I then filled them with wood chips and installed them on my hives and just like that, even during one the foggiest, wettest weeks of the winter, all the moisture was wicked away from inside the hives and my bees were saved from certain death. Hurray for moisture quilts!

So if I had to pick one piece of cheap and easy homemade equipment to keep my bees alive all winter, it’s moisture quilts. I know of commercially available ventilation hive pieces that supposedly do a good job at keeping hives dry, but they add about another $100 to the total cost of each hive. That’s not much of an option for five-figure-income people like me. Most of my moisture quilts cost me less than $10 to make, with minimal carpentry skills required. What’s not to love?

Nonetheless, a piece of hard insulation over the inner cover is even cheaper and easier to make than a moisture quilt. And because I’m more keen on demonstrating a version of beekeeping that’s accessible to as many people as possible, I’ve decided to use only hard insulation on two of my hives this year. I definitely would not do this if my hives were still in the fog-drenched region of Logy Bay. But my hives are now in Flatrock, a place that isn’t half as foggy as Logy Bay, or even St. John’s for that matter (based on my personal observations from living in Flatrock for the past five months). My hives are in a well sheltered, elevated spot where fog doesn’t stick around for long. I think they’ll do fine without moisture quilts. If I notice condensation building up inside the hives with hard insulation, it’ll take me two seconds to drop a moisture quilt on top and fix it.

So let the games begin: Round 1 of Moisture Quilts vs Hard Insulation! This is what it looks like:

I placed a rim over the top brood box to make room for dry sugar that I might have to give the bees later in the winter. The top box (or deep) should be full of honey that will keep the bees alive all winter, but I have to be ready for the worst.

Adding a rim with an upper entrance (the round hole).

Adding a rim with an upper entrance (the round hole).

I put the moisture quilt full of wood chips over the rim. The rim (a.k.a. a spacer or an eke) is about 2.5 inches or 6 centimetres high. It could be higher. The screen stapled to the bottom of the moisture quilt bows down a fair bit from the weight of the wood chips. I haven’t perfected the design of the moisture quilts, and I don’t care. The rough ones I first slapped together still work fine.

A moisture quilt filled with wood chips being placed over the rim.

A moisture quilt filled with wood chips being placed over the rim.

This is what it looks like just before I add the top cover:

So we have the brood boxes, a rim (or spacer or eke) with a top entrance hole, plus a moisture quilt with wood chips, just enough to cover maybe half the height of the ventilation holes.

So we have the brood boxes, a rim (or spacer or eke) with a top entrance hole, plus a moisture quilt with wood chips, just enough to cover maybe half the height of the ventilation holes.

To quote Rusty Burlew, who kinda sorta invented this incarnation of the moisture quilt with some directions from Abbé Warré:

“The wood chips are light, fluffy, and basically the same temperature as the air above the brood nest, so the moist air does not condense on the wood chips at all. Instead, the humid air rises and goes right through the canvas† and the two inches of wood chips until it hits the cold inner surface of the telescoping cover. Once it hits that cold surface, the moisture condenses (just like in a regular hive) and then rains back down. But instead of the drops falling on the brood nest, they land on the wood chips and are absorbed. It is just so cool!”

You got that right. It’s the coolest thing to open a hive in the middle of winter and notice that a round patch in the wood chips are moist, but dig a little ways underneath them and all the chips are dry, just like the warm and toasty bees down below.

I can feel the warmth from the bees underneath the moisture quilt. (March 26, 2014.)

I can feel the warmth from the bees underneath the moisture quilt, even through the moist wood chips. (March 26, 2014.)

The wet chips never get soggy because the moisture is pulled out through the ventilation holes. It’s brilliant.

† Rusty uses canvas in her moisture quilts instead of metal screen. Canvas is obviously better at keeping the wood chips separate from the bees. Some of the smaller particles of the wood chips fall through my screen, but it’s not much and the bees have no trouble clearing it out of the hive. Most of it falls down to the bottom board anyway.

Clearing away the wood chips allows me to see what the bees are doing. (February 1, 2014.)

Clearing away the wood chips allows me to see what the bees are doing. (February 1, 2014.)

An advantage to using screen instead of canvas: I can look through the screen and observe the bees clustering below.

With any luck, I shouldn't have to do anything with this hive until next April.

With any luck, I shouldn’t have to do anything with this hive until next April.

Now moving onto the less scintillating but nonetheless respectable hard insulation method. The set up for this hive also starts with a rim, this time a solid rim without an entrance hole drilled into it. Then the inner cover in the winter position, which means the flat part is on top and the entrance notch opens right into the hive. I keep meaning and forgetting to tape over the inner cover hole. I don’t think it matters. Supposedly the bees can chew away at the insulation and make a mess, but I’ve never had that happen.

3-deep hive, solid rim (or spacer or eke), an inner cover in the winter position, and a piece of hard insulation on top.  (The top cover is missing from the photo.)

The thick piece of hard insulation has an R-7.5 rating. I don’t know what that means. All I know is the insulation keeps the cold out so that whatever moisture or humidity rises to the top of the hive is more likely to leave through the top entrance instead of condensing on the ceiling and dripping down on the bees. Here’s what it looks like with the cover on top:

Now with the top cover on. The duct tape fills in cracks between the deeps, even though the cracks probably provides some extra, harmless ventilation.

The duct tape fills in cracks between the deeps, even though the cracks probably provide some extra, harmless ventilation.

I have five honey bee colonies going into winter this year. Three of their hives have moisture quilts set up exactly as I’ve shown. Two of them have hard insulation on top. Normally I’d use moisture quilts on all of them because I know they work no matter what the weather conditions. But I’m also aware that not everyone who takes on beekeeping as a hobby can build things. Period. Or has the money to build things. So as much as I love moisture quilts, I think it might be helpful to demonstrate the cheapest and easiest method of over-wintering honey bees in a Langstroth hive using hard insulation, and comparing those hives to the hives with moisture quilts. Let’s see what happens. To be continued…

P.S.: My hives also have quarter-inch / 6mm mesh over the bottom entrances to keep shrews out. I’ll put mesh over the top entrances soon as well. The duct tape fills in some of the cracks between the deeps, though I’m not sure it’s necessary. I’ve chosen not to wrap my hives with Bee Cozies or roofing felt or any of it this year. That could be a mistake, but I’ve had several hives over the years survive the winter without any kind of wrapping, and none have died that weren’t wrapped. So let’s see how that works out too, shall we? Either way, I’m glad to be done with the bees for the season. It’s been difficult building my colonies back up from nearly being destroyed by shrews last year. And I’m still not sure what will happen over the winter. Two of the queens are getting old and could die before the spring. The new colonies seem healthy with plenty of honey, but they’re not massive. I’m not sure how well they’ll react to extreme weather if any comes along. But in theory, I shouldn’t have to touch my hives again until April. I won’t be taking any bets on that one, though.

November 10th, 2015: I had to kill the experiment, though not necessarily because the hard insulation wasn’t working. I wrote about in Switching Out Hard Insulation for Moisture Quilts.

February 12th, 2016: I killed the experiment as a better-safe-than-sorry precaution. But I don’t think it was necessary. I think the hard insulation would have been fine.

July 2019 Postscript: I’ve had mixed results with hard insulation where I keep my bees in Flatrock, but I’m not sure I can blame those mixed results on how I winter my bees. At the moment, I would say Flatrock is the worst place I have kept bees on the island of Newfoundland. It’s the worst place because it’s close to the ocean. Specifically, it’s close to the bee-freezing Labrador Current, which I can see from my house. I keep bees in another location farther inland away from the ocean, and those bees do remarkably better than my bees in Flatrock and always have. I’m not sure if hard insulation or moisture quilts would make much difference to my bees in Flatrock. There’s only so much that can be done to fight off the Atlantic Ocean.

10 thoughts on “Moisture Quilts vs Hard Insulation

  1. Do you think it matters what size the wood chips are? I’d probably have to get the bedding stuff from pet stores, which looks smaller than what you have.

    I tried dry sugar at one point last year but the bees ignored it so I won’t bother again. They seem to prefer syrup or fondant as it doesn’t go so hard, probably easier to digest.

  2. Smaller chips might work better at absorbing moisture. Good point. I use the pet store stuff, hamster bedding, whatever it’s called. One brand seemed to contain smaller chips, though I’ve had no problems with the larger wood chips.

    I use the same wood chips in my smoker too, mixed in with old burr comb and other things to keep the heat down. It’s probably not the best smoker fuel I could use, but seeing how I have a gigantic compressed bag of it, I might as well use it.

    Syrup in the winter isn’t in the realm of possibility where I live. It’s just too cold. If your climate is warm enough that the bees can take syrup in the winter time, that might be why they don’t touch the dry sugar. I don’t think the bees are able to eat dry sugar unless it’s cold. The bees’ warm breath condenses on the cold sugar, which subsequently allows them to digest it in a viscous form. I think that’s how it works. However, similar thermodynamics should come into play with fondant and hard candy too. So there goes that theory.

    Here’s another question: If the bees need a certain amount of moisture to digest the solid sugar (whether dry sugar or hard candy), could the moisture quilt effectively starve the bees by removing the moisture they need to dissolve and digest the sugar? I don’t know.

    • Thanks for the info. It’s still just about warm enough for syrup here as we’re having a mini November heat-wave, but soon will be too cold. Most beekeepers here don’t use dry sugar, I just tried it as an experiment but to be fair it may not have been cold enough.

      The fondant is more convenient for me though as it can just be put easily over the crown board in a block, so as they seem to like that I’ll stick to it. It contains its own moisture too so then I don’t need to worry about the bees not producing enough to digest it! But if you’ve used the moisture quilt in combination with dry sugar before, and the bees have eaten it ok, presumably they still have just enough moisture?

  3. Fondant always seemed like the perfect winter emergency food to me, partially moist so the bees can eat it immediately, and easy to handle — just slip it in.

    I still consider the moisture quilt & dry sugar combo an experiment. Some colonies devour the dry sugar. Others barely touch it. Though none have yet starved with sugar in the hive. They eat it when they need it, I suppose.

  4. Hello Phillip,

    Do you observed increased storage consumption or more winter bee loses in the hives with “Moisture Quilt”?
    Do you uses “Quilt” combined with screened bottom board? Isn’t it too draughty?
    Thank you in advance for answering and sorry for spellings.

    Best regards from Gliwice, Poland.

    • Hi Konrad,

      I used a moisture quilt on a hive with a screen bottom board twice. It wasn’t too drafty. The bees survived the winter. However, that particular hive was fairly sheltered from strong winds and was buried in snow for half the winter.

      I’ve only used moisture quilts for two winters, so it’s difficult to say if the bees eat more honey with moisture quilts on the hives. I haven’t noticed much difference, though.

      As for winter loses, again, it’s difficult to say after only two winters. I lost several colonies last winter, but that had nothing to do with the moisture quilts. Shrews got through my mouse-proofing mesh and ate most of my bees.

      I’m not sure if the moisture quilts keep the bees warmer than any other method of insulation, but they certainly keep the bees dry, and I’ve never lost a colony because of cold temperatures inside the hive.

  5. I’ve used moisture quilts since 2012 with good results. Because of sugar’s hygroscopic quality, it seems moisture rising would condense more readily on the sugar (which is below the quilt) than it does on the wood chips. Anyway it hasn’t stopped my bees from consuming the solid sugar.
    You aren’t really creating much convection, because the wood chips keep most of the warm air below them.

  6. I found this moisture quilt design that provides space for a spring / summer jar feeder.

    I’ll probably never build it myself because I’m tired of building things, but I might give it a shot if I ever need to build a new moisture quilt.

  7. Yes, I put on a moisture quilt here on the coast in B.C. I staple screen 1″ up in top box and put paper on frames with sugar. You Don’t say if you put in bottom insulation or leave screen bottom open, or plug hole on top in cold, or put sticks under top lid.

  8. I don’t use a moisture quilt on every hive in every location, but when I do, I usually put a rim underneath it to make room for sugar. The moisture quilt is filled with wood chips. I don’t leave the screen open. I don’t plug the hole up top because I don’t have a hole in the top cover (if that’s what you’re talking about). But if I did, I would could plug the hole. The moisture quilt doesn’t work if the moisture that is absorbed by the wood chips can’t evaporate out some ventilation holes. I think that answers your questions.

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