Top bar bee hive

In previous posts I mention bees and honeybees. Here are some pictures and plans for the two top bar bee hives I built. I built these a year apart. I put out the first hive in the spring hoping to lure a swarm into my hive as there are always plenty of bees in the my garden.
Top bar hives have been around for a while often associated with Africa which is where they were first deployed. I'm not sure who "invented" this type of hive, but the goal in Africa, was to have a low cost hive to replace logs, which were the previous type of hive used there. In using logs or skeps, inverted baskets, the bees are usually killed when harvesting the honey. Therefore, using a topbar hive, or any hive with removable "frames" is an improvement from the stand point that the hive doesn't need to be destroyed to harvest the honey. Further since single combs can be removed, it allows for non destructive hive inspection and manipulation. This seems to be the distinction between keeping honey bees and working with honey bees.
Top bar hives don't use a "frame" as is typical with many other hive styles. The most popular being Lorenzo Lorraine Langstroth's moveable frame hive. While L.L. Langstroth's hive design is the worldwide standard used today some 250 years after its development, it does require greater carpentry skills, and tool to extract the honey from its frames. While all of these are available for purchase, it seemed starting out I wanted to begin smaller scale. An advantage of Mr. Langstroth's design is the re useability of the comb once the honey has been extracted. Honey bees must consume 7-10 times the amount of honey to build the same amount of wax comb. Therefore they are much more productive, in terms of honey production, if they can reuse their wax combs.
In harvesting honey from a top bar the individual wax combs are typically destroyed in the extracting process. There are people who believe this is better for the bees in that they must rebuild wax comb to replace those taken. The advantage being that the old comb specifically the wax can accumulate environmental toxins. Most beekeepers using Lorenzo's or others frames swap the wax after several seasons for the same reason.
There are two basic top bar hive designs, Tanzanian and Kenyan. With the distinction being the Tanzanian hives have vertical sides where the Kenyan's have angled sides. In theory the honey bees don't attach their comb to the walls in the Kenyan hives making the top bars easier to remove. In my internet research it seems there is much debate about bees attaching to the walls, but with the help of CAD and a power circular saw I felt that I could easily build an angled side hive.
The critical dimension in all hives of whatever design is what is called "bee space". Bee space is the distance that two bees need when passing each other on apposing surfaces. Any area in hive smaller than bee space is generally filled with propolis (bee glue), larger areas are filled with comb. Bee space is roughly 3/8 of an inch.
Top bars are generally 1.375 (1-3/8") wide, although I have read that may beekeepers use wider 1-1/2" inch bars near the edges of the hive for honey bars. This 1-3/8" bar width gives the bees enough room for natural comb with the required bee space between the combs, assuming they build straight comb.
While the width of the bars are determined by bee space, the length of the individual bars are dependent on the hive design. For mine I settled on 18" (457mm). So far I have built two hives. I designed them with to both have the same 18" top bars so that I could interchange them when needed.

For the length of the hive's I read some designs at 36" and some longer. I used 36" because my hive sidewalls were constructed from 1 x 12's which are easily obtained in 6 ft lengths. I the above photo you can see the 25 numbered top bars plus the follower board. All of these measure 1-3/8" wide, so 25 top bars + 1 follower x 1-3/8" = about 36 inches. Actually is just under that, you can see a shim next to top bar #1 which measures 3/8".
In this hive the top bars rest on the top of the sides of the hive.

Here is my cad drawing. I found many websites stating that the angle of the walls should match the 120 degrees in a hexagon. The vertical measurement was determined by the approximate width of purchased 1 x 12 pine boards. These are 3/4" thick, which seem pretty standard for most hives.
The differentiating part of the design is that the top bars sit on top of the angled side walls, held in place by gravity.
The top bars themselves are built from a bundle of wood I got at the lumber yard that they had in the "cull" section. It was all pretty good redwood 1x2x8ft. It was reasonably priced at about $11. enough for about 3 hives (75+ top bars). I ran the boards through my planer to skinny them to 1-3/8" wide.
In doing more research I found designs where the top bars were recessed into the hive and rested on cleats built into the walls of the hive. This means the hive cover will rest on the hive body not the top bars. I have no idea if this will matter or if the bees will prefer one design over the other, I suspect not.

This hive was constructed with 3/4" plywood so I could increase the vertical dimension. I used the same redwood top bars in this hive.
Both hive have entrance for the bees on the ends. Which about 1/2 of the designs seem to have, based on my internet research. The other design is to bore holes in the angled walls.
I cut large holes in the floor of both hives and used 1/8" wire mesh stapled in place to cover those holes. The prevailing thought is that any mites that the bees clean off themselves while in the hive will fall out the bottom vs. climbing back onto a bee from within the hive.

While somewhat difficult to make out, the above shows my hive cover. It is made of wood covered with galvanized steel. The steel was stapled on the sides I drilled several holes and I used spray foam in those  holes to get a tighter fit. Before I did this the metal was pretty loose in on the top and I worried rain or hail would drum my bees into a frenzy. This cover telescopes over the top bars and has a 1/2" sheet of rigid foam insulation on the inside of the wood. So from top to bottom it is paint, galvanized steel, spray foam, plywood, rigid foam. The color was selected from the "oops" section of the outdoor paints that had been returned to the store. $5 for a gallon of high end outdoor paint. Yes I know, cheap.

So here they are in the bee yard. The first one is the one on legs. For the second hive I replaced the railroad tie with another block so that I could remove the red brick and stabilize the hive a bit better.  I also screwed a 2x4 to the back (look just above the rear block) to further stabilize.

This winter I took a beginning beekeeper class with the local beekeeping organization, The Boulder County Beekeeper's Association. $75. for a 8 week class. Money very well spent. I purchased a couple of packages of bees from one of the members. He drives to California every spring and picks up 300 or so 3# packages of bees. They are scheduled to arrive in late April, timed to correspond with our dandelion bloom. This is the first reliable source of nectar and pollen for the bees in our area, Boulder, CO.
So more to follow.