After a lot of trial and error I finally settled with TJ Carr/John Bradford's TBH dimensions which can be found at
There are plenty others like the ones of Phil Chandler or Dr. Wyatt Mangum.
The main advantage of the NMBA TBH plan is, that the top bar length is on the larger side with 18.25" (ca. 47cm) whereas maintaining 120° angles on the sloped sides to avoid comb attachements but still being rather shallow in height with 9"-9.75" (ca. 23-25cm).
This leads to a very decent comb size while maintaining a very large area of comb attachment to the top bar length. Thus no comb attachment to the sides or comb breakage from the top bar becomes a real issue.
In some hives I use movable end boards, this allows for easier inspection from both ends. I derived my take on this from Sam Comforts TBHs, he uses a very similar approach. I didn't come across this idea elsewhere.
I use solid bottom boards. Screened bottom boards (SBB) don't really help you much in tracking mite drops etc. There are more accurate methods. And SBBs tend to support a rather drafty environment in hives.
Also in my experience bees prefer solid bottom boards.
"Warm way" vs "cold way"
A question of taste and belief. I prefer end board entrances and hence decided for "warm way" arrangements in KTBHs. But also in Warré's I use warm way arrangements all year round, in contrast to most Warré beekeepers.
I've researched the "warm way" vs "cold way" topic quite a bit (the majority of Dadant/Langstroth/Zander/national hive arrangements nowadays often favour "cold way" arrangements), but couldn't see a lot of a difference. Bees don't really care.
Currently I'm experimenting with a corner entrance as well, but have no conclusions yet.
I use different top bar dimensions. Due to the hive design all of my top bars have the same length of 50cm (which is easy to cut without waste over hear in metric Germany, as typical lath lengths are multiples of 50cm).
I believe in regressed bees by natural comb renewal. My approach is to start a hive with 36mm (with a wax guide/starter strip) top bars, once I have two straight brood combs I put a 32mm top bar in between, to start the regression in a checkerboard style: 36|32|36|32|36.
I don't use any guides on the 32mm top bars, as I only put them in between fully drawn 36mm top bars.
When I have enough 32mm top bars fully drawn, I proceed with the regression by moving the 36mm top bars to the back of the brood nest and only use 32mm top bars: 32|32|32|36|36.
Occasionally I might slide in a 36mm top bar, in case the bees aren't regressed as much. In general bee regression to smaller bees with 5mm cells takes several comb renewals, so don't expect quick results. Instead it will take a couple of years(!).
For honey comb drawing I incorporate 38mm top bars, which I put in between broodless 36mm combs at the end of the broodnest, only one comb at a time, though. Also my 38mm top bars have no guides.
I use a lid of plywood that I put on top of the top bars. Different heights of the top bars lead to some ventilation in the summer. In the winter I put 30mm fibreboard insulation in between the top bars and the plywood lid, to provide for less excess heat through the top bars.
Note that all my hive stands (except the Warrés) are in a rather shady environment. If sun exposure is high, I would put additional bars between the lid and the top bars to provide for better heat ventilation during summer.