Top bar hive design

This post describes the top bar hive design I am currently using, which is slightly modified from the Les Crowder design to suit my situation. I have written other posts about my top bar beekeeping efforts, including putting a top bar super on a framed hive, and putting a brushed swarm into a top bar box. 

My first top bar hive at home in our hillside orchard. The framed nucleus hive above it provided the bees for a brushed swarm to start a top bar hive

What top bar design to use?

There are heaps of top bar hive designs visible on the internet. Many tend to be quite complex, and the array of options is confusing to the beginner. While getting started with top bar hives, I've found myself settling on a frugal and simple design which I have adapted for my circumstances. 

I've taken a lot of inspiration from Les Crowder, reading and frequently referring to his book (Top Bar Beekeeping), and watching him on youtube (this one is my favourite). Les clearly is focussed on the bees instead of the appearance of their accomodation, perhaps like those families who are more interested in relationships and good health than the architectural status of their houses. He uses many re-used materials, and only does as much work as is required to make the parts do their job. There’s a lot to be learnt from this approach (I also appreciate the frugality of Sam Comfort’s beekeeping, e.g. this video of him inspecting a top bar hive). 

Hot climate design

Living in a climate where it can get very hot, I’ve followed Les’s lead in using a relatively long bar in a relatively shallow box. This means the combs carry less weight per length of bar, and are less likely to break off in hot weather when the wax gets soft and weak. I’m also providing insulation above the top bars, to reduce the flow of solar heat from the roof, which could heat the top bars and cause combs to soften and fall. 
I'm still considering how best to provide ventilation to my hives. I'm interested that many top bar hives have mesh floors, that give a lot of ventilation, but I wonder if this would make it hard for the bees to keep warm and dry in our winters. 

Dimensions

The key dimension for any top bar hive is bar length. Les uses bars 20” long (508mm), which I rounded down to 505mm (cold climate beekeepers often use shorter bars in deeper hives). Because I see a lot of value in standard, exchangeable bars (e.g. when helping other beekeepers start hives) I was a bit torn between Les’s size and the “Standard top bar” size of 19 1/2” (495mm), but it’s easy to cut bars short if needed. I’ll say more about my top bars later. 

The internal dimensions of the box cross-section are 465mm max width (at top), 235mm wide at bottom and 200mm depth, which gives the sides a 60* angle. 

Hive end board dimensions

End boards and divider boards are made to this cross-section size, cut from 200 x 25mm boards. The tops of my end boards are flush with the tops of the side boards. This makes it easy to put on a capping piece at the end with an entrance; it’s also easier to mill 200mm boards than 250mm boards. This is different from some designs that have end boards standing above the side boards (e.g. Les Crowder).  

The box sides are 250 x 25mm boards, square edged (these could be made from 2 boards joined together). The bottoms are 235 x 25mm boards (or narrower boards fitted together), with the edges angled at 60*. 

I’ve made my full-size hives 1200mm long. This is longer than some designs (Les uses ~1100mm long to fit in his truck), but it gives the bees some spare room in case of neglect during a honey flow. Currently I find the extra length useful for temporarily holding bars and combs I’ve lifted out of the hive.  

I’ve also made a few 10-bar top bar nucleus hives (nukes) which are the same cross section, but 420mm long (outside dimension: side and bottom boards are 420mm long). 

Here's a 10 bar nucleus hive. Note how the sides are made from narrow boards, avoiding the need for 250mm-wide timber. I haven't put an insulating board under the roof of this hive yet. 

The nukes are very useful for making a split (dividing a hive to make a new hive). They are great for collecting and initially housing swarms: small enough to carry to the swarm. They are also easy to transport when setting up hives in another place - I try to avoid moving full-length hives. An empty nuke is also a very useful toolbox and top bar comb holder when doing beekeeping: when you lift out combs from a top bar hive, you need somewhere to put them: you can’t just lean them against the outside of the hive like you can with a Langstroth frame. 

Hive entrance

My hives have an entrance at the top of one end board. The opening is created by a slot 150mm wide, 10mm high, cut into a piece of 30mm x 20mm x 505mm wood, nailed on the top of one end board. 

The centre stick in the picture is an entrance bar, with 150mm wide slot in the middle. On its right are 2 spacer bars, for when the standard bars don't quite fit into the hive

The inside top edge of the end board needs a bevel cut below this opening, so the first top bar doesn’t block the entrance.  

Here's a bevel on the inside of the end board, ready for the entrance bar to be nailed on top.  The bevel allows the bees to enter without being blocked by the first top bar.

And here's what the entrance looks like from the inside with the entrance bar in place. 

Most of the smart top bar beekeepers seem to put the hive entrance at the bottom of one of the hive’s long sides: Les puts his close to one end as a 10mm x 150mm slot, some put 3 x 25mm holes in the middle (e.g. Philip Chandler , Adrian Iodice). I’m sure they’re right about the benefits of a low-down side entrance, but I’ve put my entrance at the top of the end to fit with my local conditions. Because of the steep slope I keep my hives on, a side entrance would require me to stand in front of the entrance while working on the bees, creating an air-traffic-control problem, irritating the hive and giving me more risk of bees going up my shorts. An entrance at the bottom of the hive would also be easily obscured by fast-growing weeds in our sub-tropical paradise. I take comfort from Michael Bush, who describes how he uses a top entrance created by leaving a gap between the end bar and the hive end board. My entrances are easily removed and a side entrance could easily be cut in if my hives are moved to somewhere flatter some time. One of the splendid things about these top bar boxes is how easy it is to try a diversity of ideas, even if you stick to one top bar length. 

Top bars

So far I’ve been using 35mm wide top bars, following Les Crowder, 505mm long. Adrian Iodice also uses 35mm bar width. Many top bar beekeepers use 38mm (1 1/2”) wide bars all through (Standard top bar and Philip Chandler both use 38mm wide bars). 

Some people use wider bars for honey combs and narrower for brood. This is similar to Australian framed hive beekeeping, where it’s common to use 10 frames in a 10 frame brood box, but only 9 frames in honey supers. This makes wider honey combs that are easier to uncap when extracting honey, and requires less wax and fewer frames per kg of honey. Using 2 different widths of bars would add significant complexity to using a top bar hive, as combs that have been used for brood are gradually progressed outwards to become honey combs. Philip Chandler’s top bar hive plans mention that some beekeepers add 6-8mm wide shims between honey bars during a flow. Occasionally I’ve used a few spacers (about 8mm) for bars with extra-wide honey comb. 

My first batches of top bars had a square ridge machined into the bottom edge, intended to help guide the bees in comb building (does it?). I made these from 35 x 25mm timber, and used my circular saw bench to saw away the wood on each side of the ridge, leaving a 35 x 20mm bar plus ridge. Making these ridges adds a significant amount of time to bar-making, and requires the timber to be 5mm thicker than it would be without the ridge. 

Here are my 2 types of top bar, plain on the left, ridged on the right. Both have a cross-cut groove near the end to locate the bar on the top of the hive side

Watching Les Crowder’s video I noticed that although his book advises you can nail on a cleat along the bottom of the bars, Les’s bars visible in the video are plain flat on the bottoms (watch from about 11min to 14min). Les’ bars are a diverse collection of timber scraps: the right width and length, but otherwise anything goes (including what looks like a strip of short-grained 10mm plywood). His combs, however, appear remarkably straight and well aligned to their bars. I now suspect that there isn't much value to making top bars with complex shapes on the bottom, hoping to influence comb building. 

Since working this out, I’ve been mostly making plain 35 x 20mm bars, flat on the bottom, rough-sawn unless planing is necessary to make a straight bar. In the hives, I don’t find the bees align their combs better on either type of top bar. Both require some straightening of combs at the ends. The bees actually appear to attach their comb more strongly to the bars without ridges. 

Here's a ridged bar, standing upright. See how a lot of the comb is attached only to the narrow ridge on the bar bottom, with occasional extra reinforcement onto the bar base.

Here's a ridged top bar, showing how little interest the bees have in the ridge.

Here's a flat-bottomed bar, with the comb attached more broadly and strongly along the bottom of the bar. 

Following Adrian Iodice’s method, I have been making a cross-cut slot near the end of each bar, which engages with the ridge of one hive side board. This is to maintain more consistent alignment of combs in the hive when replacing bars, and cause less interference with the bee space between the comb and the hive sides. Maybe I’m being too fussy…

Roof

I’ve used a very simple roof: a sheet of corrugated iron, 1450mm long and 740mm wide, edges turning downwards, on top of some 25mm pine boards, on top of the top bars. The hinged roofs on the fancier hives would have real advantages: light and easy to lift, no need to find a place to put them down. However for now, I’m stuck with keeping hives on a steep slope, I’m using top, end entrances, and hinged roofs wouldn’t easily work. 

I cut the corrugated iron so it has about 100mm overhang all around, keeping sun and rain off the hive walls. This requires cutting along the corrugations, which isn’t easy. I could use an angle grinder and disc, but that burns the zinc coating and leaves a nasty burr, so I manage with special flat-bladed tin snips (or my friend’s electric snips!). I use a couple of bricks to hold the roof on in storms - perhaps I should tie down with a strap or rope like Les does. 

Here's the wooden insulating panel, on top of the top bars

Under the iron I have a wooden panel which is purely to add insulation from the heat of the sun - I really don’t want the bars to heat up on a hot, sunny day and have combs fall down. It is made from 25mm thick pine boards held together with 3 cleats across, screwed together with type 17 screws. I put a layer of reflective foil building paper on top of the boards to reflect heat from the corrugated iron. The cleats, on top of the boards and foil, create an air space under the iron to further reduce heat. 

Materials

One of the things I most love about top bar hives is that I can make them myself from timber I mill myself, from trees we grow. 

So far I’ve made most of my boxes from untreated slash pine (Pinus elliottii - the most common exotic pine in this area). This is mostly due to having some old boards to use up, plus my reluctance to use more valuable hardwood when I’m still at an experimental stage. With 3 coats of water-based exterior paint (from the tip) on the outside, bare wood on inside, I expect a reasonably long useful life. The shallow profile and sloping side boards, under an overhanging corrugated iron roof, mean that the top bar box rarely gets wet at all - unlike a framed hive, with tall walls that will be running with water in any rain. 

To make hardwood hives, I’m milling 25mm boards of lighter eucalypts such as blackbutt, flooded gum and Sydney blue gum. Narrower boards can easily be butt-jointed, with cleats to hold them together when required: the bees will fill any shrinkage gaps they don’t like with propolis. Painted, covered and on a dry base, these should last for decades. 

I’ve made the top bars from whatever offcuts I have available from sawmilling, lately mostly slash pine and flooded gum. Additionally, I’ve been experimenting with milling some of the smaller, rarely used rainforest timbers that go to waste locally, and experimenting with non-chemical treatments to avoid beetle damage. 

I screw the hives together with 50mm type 17 galvanised hex head screws, 12 or 14 gauge, whatever used screws I can find. I pre-drill holes for the screws, I dip a little grease on each screw before insertion, I paint the joining faces of the wood, and put a little paint in the screw hole, before screwing the pieces together. These screws are very durable, very strong, and easy to remove when desired. 

Home grown

All the wood I use for my hives is milled here on our place, and nearly all is grown here in our valley. The Eucalypt wood (flooded gum, blackbutt, Sydney blue gum) is from trees we planted here in the late 1980s/early 1990s. The slash pine is from trees planted in the mid-1900s that are old and falling apart. On our fertile, well watered soils, all these trees grow very fast and are light, easily milled timbers. Because the longest piece of a top bar hive is 1200mm, it’s easy to find sections of even a crooked log that can be cut into the various parts of a hive. While it’s legitimate to grow trees for timber, I haven’t ever cut a tree just for wood. The trees I mill are felled for other property management reasons, such as maintaining sunshine on our house, solar panels or garden, or thinning over-crowded forest. If you grow forest, you will have lots of wood to spare. 

I produce hive wood with a small chainsaw mill (here's a post about my current Alaskan mill) and some crude, solar powered circular saw equipment. I can cut 1” (25mm) thick boards for the hive boards with the chainsaw mill. Some of my top bars are specially sawn from small logs, milled into 40mm slabs to dry and later resawn by circular saw; most are cut out of offcuts from my other timber work activities. 

Here's a stack of 40mm Pencil cedar slabs, just long enough for top bars, seasoning in the shed loft

It’s so satisfying to have a good use for small pieces of wood!

Both the hive for the bees, and most of the nectar they harvest, are products of our native forest, along with all our firewood, building wood, charcoal for cooking and blacksmithing, etc.. We live from our forest.