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.
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.