beekeeping equipment ventilation

The best ventilated gabled roof

A ventilated gabled roof is one of my favorite pieces of beekeeping equipment. Warm air holds moisture, and the warmer the air, the more moisture it can hold. Since a summer beehive is loaded with moisture from both bee respiration and drying nectar, the hive can quickly become a damp, mold-infested environment that is not healthy for bees or good for making honey.

Winter is also problematic. Inside a cold hive, the bees’ breath warms the air immediately around the cluster. This warmer air rises until it reaches the cold inner cover where the moisture condenses, often dripping back down on the bees. In either case—winter or summer—the faster you can get rid of moist air, the better.

The ventilated gabled roof provides a double whammy to moisture-laden air. First, the gabled roof provides a place for this air to collect that is well above the supers. Secondly, the vents on each end of the gable give the air a way to escape. The extra height provided by the gable is important because the greater the distance between the inlet and the outlet, the better the draft. Assuming your air is coming in through the screened bottom board, the gable provides a nice tall “chimney” to draw air through the hive.

Of the ones I’ve seen, the very best ventilated gabled roof is made by beekeeper Bill Castro of Bee Friendly Apiary in Maryland. Bill wrote to me last year about the severe moisture problems he encountered after relocating from Colorado in 2008.

I had no issues with moisture until I moved to Maryland. . . . I immediately noticed how the build-up of moisture under the inner cover helped to form mold and mildew. I knew that the humid air here was a serious issue with cooling, since evaporation is nearly impossible. . . . After the winter of 2008, I opened the colonies in spring to find mold and mildew had built up all over the underside of the inner cover, on the tops of the upper super frames, and down the sides of the supers creating a very unhealthy environment.

I immediately took out all the frames and the inner covers . . . and scraped them down and sanded them clean. I then quickly brain-stormed and decided to make vented gable top covers and screened bottom boards. Since then, no issues with mold and mildew and the colonies perform much better.

Bill’s covers are made from pine with aluminum sheet metal covering the roof. The 1.75-inch vent holes are placed as high in the peak as possible for maximum effectiveness, and they are covered on the inside with #8 hardware cloth. The aluminum is folded over with no sharp edges, and a slight overhang protects the vent holes from sheeting rain. The woodwork is professional with tight seams, smooth edges, and star-drive wood screws. The slanted portion of the telescoping roof sits on the top outside edge of the hive, resulting in much less surface area where bees can be squished between cover and hive. Overall, it is a beautiful and effective design.

Update 6/23/2016: Bill no longer takes mail orders for his gabled roof.


Hives with ventilated gabled roofs. Hives, covers, and photo by Bill Castro.

Here is an overview of the gabled top cover. I make them from 1 x 12 materials for the gabled sides and side rails. The top cover material is 3/8-inch plywood and all joints are screwed together for durability. I don’t like to use wafer board as it smells terrible and is loaded with formaldehyde and I don’t want that near the bees.

All measurements are made for easy installation on 10 frame Langs.  All materials are easy to obtain from most hardware stores such as Home Depot or Lowes. The metal top material is extruded aluminum 24 inches wide. It can be found at any roofing supply house, but is sold in 50 foot rolls. It can also be found at most hardware stores that carry roofing supplies.


Bill’s ventilated gabled roof plan.


  • Rusty –

    Thanks so much for writing about the gabled roof and for the pics! Those are great! I am going to have to contact Bill Castro and ask him he makes those for other people!

    Thank you!!!

  • These do look nice. I had the same problems with excessive moisture and mold, and came up with a similar solution that seems to work about the same. It isn’t as attractive, but it also doesn’t require making any new equipment. The tops of my hives are just an inner cover, and on top of that an empty deep super, and then the outer cover on top of that. This gives good ventilation, the notch on the inner cover gives an upper exit that is above the snow line in the winter, and it provides a protected place to put in feeder pails. And I have never had any trouble with the bees moving up and building comb in that upper chamber (although they seem to be kind of reluctant to build comb in the local climate anyway, so it might not work quite as well in warmer areas). And setting a rock on top is plenty for keeping the wind from blowing the tops off.

  • Hello everyone,

    Thanks for the cudos Rusty. I hope everyone enjoys this gabled top. There are other commercially produced models similar to this design. I used the most economical materials I could find to make these tops. I don’t have any fancy or expensive tools or jigs. I used all regular power tools and hand tools to make them.

    All materials can be locally acquired at hardware stores and assembled in a single afternoon. I make mine in large batches since I have numerous colonies, but a person who is looking to make a single or a couple tops could easily find the appropriate amount of material for the job. I will take some pictures of my template I use for the ends and also note the dimensions of all the wood components. I really focused on simplicity of design and assembly.

    • Bill,

      That would be great! I love this roof and I’m sure others would find it equally impressive. The part I worry about doing myself is the aluminum. You got it very smooth with no nasty edges. That seems like it would be difficult. Any pointers?

  • Just found some nice 1x12s in the barn and was just going to guess at making one of these gabled roofs for my hive today. Then I saw Bill’s message, then the date, and I am holding off until he can post something. Those measurements would make things sooo much easier. Thanking you in advance.

  • Hello again everyone,

    Sorry it is taking me sooooo long to get additional information out for everyone. I have family here and wake up early to get my own personal work done before everyone awakens for breakfast, but I will try and get a plan and better detailed pictures available for anyone interested in making their own tops.

    In regards to any possible burr comb build up inside the “attic” of the gabled top, I highly suggest using a standard inner cover under the top as we would with any other type of top cover. As long as the colonies have ample empty area within the hive, open frame space, the bees will ignore the area within the gabled tops. I have left the gabled tops on a couple colonies without the inner cover and have had the bees start pulling comb there, but not often at all. Because the covers have end vent holes, it is very easy to peek inside and see what the bees are doing. Any comb being pulled on the cover can be very easily scraped off and saved for candle making or any other craft needing clean bees wax. There will also be a probability that some colonies may start propolizing the vents closed, I harvest this bulk propolis and make tinctures with white alcohol for personal use that comes in VERY handy for cold and flu season.

    I hope everyone is having a great season and having fun with the bees!!!

    Bill Castro
    Bee Friendly Apiary

  • With Bill being so busy, I decided to just go ahead, make one from scratch and see what happened. I forgot to add clearance on the first try, so while it fit, but was too snug to easily take off. After adjusting it for a 1/8th-inch clearance on each side, it went on and off great, but I decided I wanted it to hang beyond the inner cover. I had only allowed 3/4 inch depth, so it just barely reached the super with the inner cover on. I adjusted the inner rails so in would hang 5/8 inch past the inner cover.

    I was pretty happy with it after that. It not only functions beautifully, but it makes the hive look so attractive in the garden. Even made one for the neighbor’s hive. She was delighted with it. I hope that by listing my mistakes, it will not only keep others from doing the same, but will encourage them to just go ahead and make it.

  • Hey everyone,

    Sorry for the massive delay in posting a plan. I have sent it to Rusty via email and she should post it very soon. This design is made with as simplistic as possible with easy to obtain materials. I have found this top to not only be effective in ventilating, but during the summer months I remove the inner cover and it becomes extremely effective at controlling small hive beetle (SHB). When there is no inner cover, the SHB will run into the gabled top cover to escape the bees. Not only does this keep the SHB away from the colony, it also eliminates the immediately available food and hiding sources near the brood, honey and pollen. I have SHB present in all colonies here in my apiary, but do not have any issues at all with overpopulation of SHB. Since I am always looking for ways to run my operation as lean and cheaply as possible, I don’t need any additional traps for SHB and no need to run out and check anything since the SHB are no longer among the colony.

    Hope this helps, and anyone looking to buy a gabled top can email me and I can send you details. I appreciate the interest and any referrals!!!

    Bill Castro
    Bee Friendly Apiary

  • Thank you so much for posting this plan. My husband and I were just discussing gabled roof tops and now we can make our own! Love this blog, it’s such a wealth of information.

  • Just to revive this topic. I am curious what would happen if there were no round holes toward the top. Will the water get condensed on the gabled surface and simply roll toward the sides like mini streams, or will it actually still drip on the bees? I hate the idea of opening the hive to outside air in the winter, so was thinking maybe if the roof could be stapled with plastic sheet from the inside, or maybe even painted to be waterproof, then condensation could simply run down without dripping. Seems it would be warmer at least.

    • Aram,

      The condensation would probably run down the slope to the sides, but it would remain quite humid in the hive. Remind me where you live so I have an idea about your winters.

  • Awesome idea…you could also make them insulated by using the landscape cloth and wood chips idea from Strathcona Beekeepers Assoc…staple hardware cloth to the bottom and fill the inside of the top with wood chips!

  • Rusty,

    I am in Auburn, WA. I like the gabled roof idea, but I do not use inner covers. My cover is a solid piece of plywood with a brick on top, but it has a 4 inch overhang with jar holes, which I bring over the frames to feed the bees, and otherwise let them hang over the hive when not feeding. To keep things multipurpose, I wanted to continue using these covers in the winter, but they do have a SERIOUS condensation issues.

    I am considering placing a pink board (R10) over my covers so that there would be no temperature drop on the ceiling and providing small upper entraces for evaporation utilizing my jar holes for that purpose. Have you tried insulating the top of your hives with insulation board in our Pacific northwest? What have been your experiences?

    • Aram,

      No, I have never used insulation on the top of my hives other than the moisture quilt. I used to get serious condensation before the quilts, now I get none. As a result, I have no plans to use an insulating board.

  • I use ventilated crown boards along with open and meshed bottoms and still get some mould on the crown boards. I have drilled a few 3-4 mm holes in each corner of one crown board and this does not seem to suffer from the problem, so I will do the same for the other hives and hopefully get rid of this problem once and for all. It seems to be just a case of lack of circulating air… I would appreciate any thoughts offered… BTW great site, thanks for the design for a roof I will give it a try; its very similar to my own, where I have recycled fence panels – larch lap and feather-edge boards… best wishes Steves Bees

    • Steve,

      If the holes in the crown board are working, then go for it. But my concern is that the air leaving through those holes wouldn’t have any place to go. If the lid or roof (I don’t know what you call it) is lying directly atop the crown board, where does the air go? Do you have a ventilated cover? In order to ventilate the interior space the air has to keep moving. It must be going somewhere if it is keeping down the mould, but I just can’t picture it.

  • Rusty, of the two wintering methods, which one do you prefer for the Pacific Northwest—the quilts with shavings or the gabled roof over an inner cover?

    • Aram,

      Funny. I prefer a quilt with shavings covered by a gabled roof. If I had to pick one or the other, I would take the quilt as long as it had lots of ventilation holes. Moisture in the hive is my biggest problem in winter.

  • Rusty, I do not know if you want to add this to the body of the blog somewhere, but I built a couple of these things and the angle for the side bar and for the peaks of gable halves is 32.5 degrees. Cutting it with an angled edge helps make flushed joining of the two halves of the roof. The side bar will end up being 1.5 inches on one side, and just short of 2 inches on the other. With enough caulking and a good paint job, one might be able to do without a metal outer membrane.

  • I wonder if you might have plans for an 8 frame. It’s a geometry challenge I could figure out I suppose. I thought I’d ask you first before I get out my protractor! Thank you for your good information!

    • Kit, the 10 frame roof will fit over the 8 frame box. It will simply have a bit of an overhang on each side. The gabled roof is what sits on top of the super.

      8 frame equipment is hardly standard, unlike 10 frame equipment. You would need to make yours per your boxes otherwise. In the worst case, build the 10 frame one, and then simply shim the sides until they are snug with your 8 frame boxes.

      My only suggestion beyond building is to paint the inside. The moist evaporations tend to settle on the roof and grow mold.

  • Rusty,
    As mentioned about the problem with mildew growing inside the top and on the side of the boxes. Is it alright to use bleach to clean the mildew if I then let it air out good before putting it back on the hive?

    • Elisabeth,

      You can, but wood has antibacterial properties that are good for the bees and wood acts to absorb moisture from the hive. It loses those qualities when you paint the inside. Plus, paint has volatile components that aren’t great for bees to breath or lick. I have roofs that are more than 15 years old and unpainted on the inside. How long do you expect them to last?

  • I ended up building the gabled roofs myself. I used OSB board for the inside and I just put a 4 inch flashing at the ridge of the gable to keep the water out. The inside of my unpainted roofs has black rot now, the painted ones do not. Could be just because I used OSB, but structurally it is still sound. The water drops that we are trying to prevent from dripping onto the bees, do form on the inside walls of the gabled roof. So maybe inside painting vs not is the “lesser” of two evils.

    I am actively converting to 8 frame (14″ boxes). Will email new construction dimensions if I succeed.

  • I built one of these! The measurements were perfect! I had a nuc that was a swarm I caught earlier this summer and I had no idea what I was going to do with over the winter, so I made a screen bottom board and one of these and took the two boxes I had set aside for triple deeps on my other two hives and settled for three double deep hives for this year. Thanks so much! I’ve read your entire blog and I check back often for your posts. Keep up the good work.

  • Yeah, I did. I sent the image to Rusty’s email. That’s for a 16 1/4 along with a 14 inch box. The only confusing part I think is the side long pieces. They are cut at an angle to be flush with the roof. I also included the cut angles that were missing in the original drawing. The rest should be pretty straight forward. Good luck.

  • Hi Rusty & Bill, and Biological Thinkers

    I made my own gable roofs to solve for ants & now humidity which has escalated this summer (climate shifts).

    Re Physics: Why specific a circumference calculation of 1.5-inch holes in the apex of the gable roof?

    Thank you for your energies.


    • Sky,

      I’m sure Bill recommended that dimension because it worked for him. It worked for me, too, but you can make it any size you like.

  • Appreciate Rusty,

    Ascertaining airflow balance regards ultimate homeostasis in Langstroth design = basically improbable.

    Trying best. Before a natural hive alternative. Time to think outside the box.

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.