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Wednesday, April 2, 2014

Top Bar Hive Dimensions

Updated: Added link to another post.

I suppose that most beekeepers use the winter to build new hives, nucs, and bars (or frames if one has Langs). Even though I don't need any new hives at the moment, I do want some nucs, so I have been giving quite a lot of thought to hive construction. In particular, I've been thinking a lot about hive dimensions.

Unlike standardized hives like Langs, Warres, Nationals, etc., TBHs come in all sorts of shapes and sizes. I have a feeling that a lot of this diversity has to do with the dimensions of the materials people are using as well as their level of woodworking skill.

If you plan on building your TBH out of wood, you're going to have to make some decisions about the following:

  • Length
  • Width
  • Height
  • Angle of the sides 
  • If/how you will accommodate a feeder



Length

Too short. I've read about a number of people with hives under 4' who have trouble because the bees fill the hive before they have a chance to cap any of it. This means that one can't harvest, and with nowhere to lay brood or store honey, the bees become swarmy and move out. I think Michael Bush and Wyatt Mangum recommend at least 4' long.

Too long. I'm not sure how long is too long really. W.A. Mangum has hives that are up to 5' long. I heard another beekeeper recommend 4' because that was the length that would fit in his truck. However, the key point seems to be that longer hives are harder to transport because of their weight and size.

Width

Width is important because it determines how much attachment area there will be for each comb. The wider the hive, the longer the bars will be. This means, potentially, the comb will have a greater attachment area. Of course, the attachment area may vary depending upon how deep the hive is -- more on this in a minute when I comment on hive height.

I have seen recommendations that the hive should be wide enough so that you can stick a bar in a Lang, get a little comb built on it (not fully built though, because you'd have a hard time putting it into the TBH), and then put it into the TBH. This size would also let you put a fully built out top bar into a Lang.

When it comes to TBH widths, mentally I've started classifying hives as "universal donors" or "universal recipients." If your width is on the narrow side, it's much easier to transfer your combs to a wider hive. If your width is wider, it's much easier to accept bars from other hives. I think this has implications for a number of things, particularly if you want to get into the nuc selling business. For example, if you plan to sell nucs, you would want to be a universal donor.

From what I've seen, narrower hives are about 15-17" wide. The wider ones are anywhere from 21-24".

You can see how the shape of the comb is determined by the interior size of the hive.

Height

The height (or depth) of the TBH determines the amount of comb that can be built downward. Why does this matter? It makes a difference because when the comb is full of honey, it gets really heavy and pulls on the part of the comb that is attached to the top bar. So the height and width of the comb should be proportional. This will ensure that the attachments are strong enough to support your comb.  



So the million dollar question is "What is the best ratio?" Honestly, I have no clue! Somewhere, I read that 11" is really the very maximum height one would want for a hive. However, you may need to adjust this height for various reasons, such as:
  • The length of your bars -- if you have long bars, you can have a deeper hive. If your bars are short, you might want a shallower hive.
  • If you live in very hot weather, you may want shallower (and therefore, lighter) comb
  • If you want to transfer the bars to a Lang, you'll want to make sure that the comb will fit the box (could be deep or medium).
  • If you want to sell nucs, you'd want a hive that is on the shallow side (again, so you can be a universal donor).
Angle of the Sides

Some people like the sides of their TBHs at a 90 degree angle to the bottom of the hive, which means the sides are straight up and down, like a shoebox. (This style is called a Tanzanian top bar hive, btw.) There are some benefits to this. For example, the hive is easier to build, and it can be made to accommodate frames from Langs. Detractors say that the bees make more attachment comb in these types of hives.

Kenyan TBH beeks use slanted slides in their hives. The premise is that bees don't like to  attach comb at the bottom of the hive. Slanted walls are supposed to feel more like "floors" to the bees and prevent more attachment at the sides of the comb. Is this true? I don't know. I found that my bees attached at the sides, but once I cut it, they rarely reattached.

I frequently hear people suggest a slant of 120 degrees because this works with the natural hexagonal shape of comb. On the other hand, lots of folks say that the angle really doesn't matter. Bees rarely build "perfect" comb, and they will build no matter what size box they are in. I have a feeling they're right since I've seen TBHs made out of 55-gallon drums, woven out of straw, using re-purposed fish tanks... you name it.


Accommodating Feeders

One other thing that might affect your hive dimensions is a feeder. Although you might want to avoid feeding as much as possible, there are times when you just have to. If you plan to use an in-hive feeder, that should be something to consider when designing your hive. It would be a real bummer to spend lots of time making a hive and then find out that the feeder won't fit inside.



I know this has been sort of a generic discussion of considerations. In another post, I've provided a list of various top bar hives I've seen online and their dimensions. If you have any thoughts about hive dimensions, please, feel free to weigh in on the discussion! I'd love to hear what works/didn't work for you.

2 comments:

  1. Good discussion points. I use the standard Phil Chandlers design ( here are my build plans http://augustcottageapiary.wordpress.com/building-plans-for-a-topbar-hive/ )
    These are 11" deep, width 15" to 5" transition top to bottom. The bees certainly seem to like it. Like you I have seen some side attachment still but they don't reattach once cut. I currently either feed in the cavity alongside the follower board using jars setup as contact feeders and a hole in the follower board OR I have a double width topbar which I have a hole cut in and a wooden ring to receive a rapid feeder. The rapid feeder id my preferred way of feeding when I absolutely have to as I don't need to open the hive at all.

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    1. Thanks for sharing your plans! I think those are the most complete, most thorough instructions for building a TBH that I've ever seen! I'm also really intrigued by your description of how you use a rapid feeder. I never would have thought of that in a top bar hive. That was really way cool! Thanks so much for sharing that!

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Thank you for your comment! I can't wait to hear what you think!