Moisture quilts should be dry

Every now and again someone wants to know what happens when my moisture quilts become saturated. One beekeeper wrote, “I can’t believe you keep a soggy pillow over top your bees.”

The short answer is simple. I don’t.

Here’s the issue: if your moisture quilts are soggy, they are not made correctly. Moisture quilts are designed to regulate moisture, not store it. As I’ve said before, nothing improved my overwintering more dramatically that moisture quilts. My hives remain dry inside, the quilts are never wet, and the bees thrive. Since using them, I’ve routinely overwintered 80% to 100% of my hives.

Remember, moisture quilts are not a new concept. They have been in use for decades by Warré beekeepers with great success, and they are easily adapted to Langstroth hives.

Built correctly, moisture quilts never become saturated. Never. In fact, before I tried them for the first time, I was convinced I would have to replace the chips mid-winter. But I never have. I’ve used the same chips year after year.

Here are some important points:

Water vapor from the hive does not condense on the bottom of the moisture quilt—that’s not how they work. Warm water vapor from the bees’ respiration (water in the gaseous state) rises. Still in the gaseous state, the vapor finds its way through the wood chips, moving between and around the pieces as air does. At some point, the vapor reaches the cold under surface of the hive cover where it condenses. That condensation rains down and is collected on the TOP surface of the wood chips—the side away from your bees.

The wooden frame of the moisture quilt contains a number of ventilation ports which allow the wood chips to dry out and also provides a source of ventilation for your hive. At most, I have seen the top ¼-inch of the wood chips become damp (and I live in an extremely wet climate). I can’t actually see the moisture except for the fact that the wet chips are slightly darker than the dry ones.

But humidity varies from day to day. So while the dampness collects on the wood chips during certain combinations of temperature, humidity, and wind, it disappears during other combinations of temperature, humidity, and wind. Basically, the top layer collects and then releases moisture over the course of the winter—some days it is damp, some days it is bone dry. But you never have a “soggy pillow” in your hive. And since the water that does collect remains on the top surface of the quilt, your bees never touch a damp surface.

Another benefit of the chips above the bees is that they provide good ventilation. Since the air must find channels or pathways between the chips, it travels more slowly than if it had a straight shot from the entrance to the ventilation ports. In other words, you get good ventilation without creating a wind tunnel through your hive.

If you want even more insulation, you can make thicker quilts which will slow down air movement even more. The ventilation ports can be restricted to the top of the wood chip layer since that is where the moisture collects.

I keep a feeder rim beneath my quilts in case I want to feed hard candy or granulated sugar. This is easy to do, and since the feeder rim is below the quilt, enough moisture will collect on the feed to make it palatable for the bees, but the rest of the moisture will go up through the quilt and then be caught by it.

The moisture quilt is such a slick system and works so well that if I were selling them, I’d give a money-back guarantee. I have complete faith in them. That said, they have to be built properly. Simply put: if you’ve got soggy pillows, you’re not following directions.



  • “One beekeeper wrote, ‘I can’t believe you keep a soggy pillow over top your bees.'”

    It’s possible she was joking, but in truth, those of us who like to sew (I was going to say “sewers” but that would create more confusion!) should be forgiven if we think of a quilt as something that goes on a bed, and would of course become damp and soggy outside. It’s what came to mind when I first heard about Warre quilts but of course now I know better. I am all set to try it this year! I just have to run up the street to Petco and buy some of the “small animal bedding.”

    This website is a goldmine and I hope everyone who is able will help support Rusty’s work with a donation.

    • Mary,

      Thank you so much for the kind words and the donation! Both are greatly appreciated.

      English is a strange language. Being a quilter myself (yes, really) I have often wondered about the word “sewer.” There doesn’t seem to be an equivalent word, and certainly sewer doesn’t work. So funny.

  • Rusty,

    I want to try and make a moisture quilt. I am sure that I can build one. Sorry I can’t seem to understand how to put it on the hive, it seem to vent to outside air. It’s simple, I am just missing something. Also would you have a picture of it on the hive.

    Already my hive covers have moisture from feeding, and I will have to continue to feed thru the winter.

    Thanks so very much.


    • Becky,

      At the moment, I don’t have a photo of one on the hive, just the photos with this post.

      But the quilt is exactly the same length and width as any super (in fact, you can build one from a regular super), so you just set it above the upper brood box. It couldn’t be easier. I’ll see if I can get a photo.

  • I am very interested in your moisture quilts. Do you ever have to change out the wood chips during the winter? Also I read where you now use #8 hardware cloth instead of canvas. Has that worked better for your hives?

    East Tn

    • Jon

      I like the hardware cloth better because it doesn’t sag. I switched part of them last year and I will be switching the rest this year.

      As I said in the post, I never have to change the wood chips. I used the same chips three or four years in a row. The top layer occasionally gets damp, but then it dries out again.

  • Hello Rusty,

    Thanks again for your inspirational information. This summer I have been collecting sawdust to use it in a pillow above my TBH as insulation. When I read your story I started thinking I collected the wrong stuff, because probably it will not ventilate good (enough). What do you think?

    Greetings from Norway, Annette

    • Annette,

      If the sawdust is fluffy, it might work just fine. Certainly you could try it and see what happens. If it starts getting too wet, you could change it later.

  • I have been using them for quite a while now with Langs. I have made them so they can flip by having a metal flywire in the middle and the ventilation holes on one side. In winter the vents are on top with the insulation layer, in summer I flip them so the vents are under the insulation. This configuration worked so well last year we did not have any meltdowns when the temperature got up the 48C and I have no condensation problems in cold, wet weather.

    Instead of chips I use hessian bag layers so I can move it easily from side to side with no mess.

  • I did something similar last year and it worked great. I used my hive top feeder and filled it with wood shavings. I also added an Imirie shim between the top brood box and hive top feeder. That way I was still able to lift the feeder and add sugar. This year I made candy boards and will use that instead of the Imirie shim.

  • Some illustrative photos for anyone who’s curious. I make jumbo ventilation rims like this…

    …and staple regular screen to the bottom to convert them to moisture quilts. I fill them with wood shavings up to the level of the ventilation holes, two or three inches, a fairly thick layer of shavings. The screen sags a bit, but high rims underneath (for dry sugar feeding) fixes that.

    I used moisture quilts last year in an area where my hives got SOAKED from rain and extreme fog in the winter. (They’re virtually set up in a swamp, too, but that’s another story.) All of my hives were bone dry within a week of installing the moisture quilts.

    Here’s a photo that shows how soaked one of my hives was before I added moisture quilts:

    Click left through the photostream to see how well the moisture quilts worked. My design for the moisture quilt isn’t perfect, but even with its imperfections, it made a huge difference.

      • Hi Rusty,

        I’m responding late to one of your comments, the one about the moisture quilt photos I linked to. You said, “I love seeing all that snow and ice in there.”

        That’s not snow and ice. It’s dry sugar (or what used to be dry sugar) melted from all the water that got in the hive. I still don’t know how the hives got so completely soaked. They look like someone opened them up and dumped a bucket of water in them. But within a week of installing moisture quilts, they were dry as a bone.

  • Hi folks

    I have made one up for my Langstroth but I used rock wool insulation instead of wood shavings or pellets. I am wondering if anyone else has used this?

    • Kim,

      Rock wool is a good insulator, but I can’t imagine using it for moisture control. Anyone else have a thought?

  • Rusty, Mary P –

    The masculine equivalent is “tailor,” from the French “tailler”, to cut.
    Maybe men did the cutting, women the actual stitching.

    About rock wool – I would think the moisture would condense on it everywhere, not just at the upper surface. We’ve never come up with a better insulator than wood.


  • Hello Rusty,
    I am a new beekeeper and have found this sight immensely helpful! I live in the Bothell/Seattle Area and so have had a lot of trouble with moisture. This year I made some moisture quilts, following your instructions. Opening up the hive, most of the wood chips on top were pretty saturated. The bottom layer was dry. I have a migratory cover so the edge ended up covering part of the ventilation holes, and there is little room for circulation. It seemed pretty wet. Is that okay?

    Also, one of my hives was a late August swarm and is therefore very low on stores. Somehow they refuse to eat sugar in any form. I have tried patties, syrup, straight sugar, everything I can and they simply will not eat it (it is good organic sugar so chemicals shouldn’t affect it). What do I do?

    • Sionna,

      If the chips get wet more than half-way down, I think you should dry them and then put them back on. Alternatively, you could make two quilts and switch them. Actually, I have never had one get very wet, just part of an inch, so you must have a huge colony. Try pulling the chips away from the ventilation holes if they are close to it. If it gets too wet, you should definitely dry the chips in the oven or something.

      Have you heard that old saying about “You can lead a horse to water but you can’t make it drink?” Same goes for the bees. You can provide food, but you can’t force them to eat it. I find that putting a drop of anise oil or something similar in the feed helps them find it (it’s dark in there). I don’t recommend that during robbing season, but you could do it now. Also, it is getting too late in the year for syrup, so stick to something solid or semi-solid.

      One last thing: save the organic sugar for household use and give the bees white refined sugar. If you don’t want GMOs, then use cane sugar instead of beet sugar. Organic sugar is not produced the same way and is usually evaporated cane juice (like the kind at Costco). It has a slight tan color due to impurities. Those impurities are fine for us, but they can cause honey bee dysentery which can be serious in the winter months. For more on organic sugar, see this post.

  • By the way, the quilt boxes, if you leave the vent holes wide open make wonderful housing units for bumble bees. I had at least 2 such families move in this year. They surely like the shavings and the free heat.

  • The moisture quilt looks like a great idea, and I can see how the design would perform well.
    I think you mean wood shavings, not chips.

    I’ve been using a 1-inch-thick piece of styrofoam set in a 3-inch rim during the winter for many years. The objective is only to prevent condensation above, and dripping onto, the winter cluster.

    Research by Tom Seeley and others (e.g. Ben Harden seems to indicate that bees need lots of water during winter, so I’m assuming that some condensation on the hive inner walls, and not the ceiling, is available to the bees when it’s warm enough for them to get to it. During winter, the underside of the foam is always warm and dry, so it achieves my objective. I have to remove the foam in warm months or carpenter ants and even the bees will tunnel into it. There’s >= a 1-inch space under the foam for sugar feeding, and I skip inner covers year-round. And there’s a notch in the front of the rim for an upper entrance.

    I’m on cold and damp outer Cape Cod, Massachusetts.

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