I'm planning a KTBH and used Google SketchUp to create a design for feedback here. It's a lot bigger than some, mainly because it's designed to hold medium Langstroth frames, and I'm planning to use some 1x11" boards for the sides.
I've been reading that the total volume should be about the same as three deep supers, or a little more. In round numbers, this one is 9" deep, 24.5" across at the top, and 14.5" across at the bottom. At 48" long, that makes about 8,500 cubic inches, or about 140 liters. That's not huge, right?
The idea with the medium frames is that I can do a hybrid approach, perhaps even put a medium super on top of that part of the TBH -- to install a nuc, to make splits, etc. This idea started with two videos at the Barefoot Beekeeper website,
Converting from Frames to Top-Bars the Easy Way (Two Parts)
So I had a idea to put a sort of half-box (cutting the box diagonally) for 14" along the insides of the TBH, to hold a set of Langstroth frames. Allowing for ~3/8" beespace at the lower corners of the frames, angling the walls at 60 degrees, and using the 11" boards, produces the following design:
I can peg the half-boxes on the edge of the TBH, and drop the medium frames down between them, I think. I might let the bees put comb on the bottom of the frames, or put a false floor 3/8" below (not shown in the diagram).
But most of the TBH, or all of it, will be regular top bars, with comb up to 9" deep and 24" across at the top. Too big?
The vertical parts of the half-boxes are two layers of 3/8" plywood, offset to create a 5/8" deep perch for the ends of the frames. I figure I can put screws through the plywood into the horizontal bar, and (not shown) plug in the triangular space at each end. (I'm looking at construction details, pdfs from here on BeeSource, for the specs.) In effect, it's sort of an inside-out box to hold the frames.
I think it's not as complicated as it looks. Wondering what problems people see. If the space under the half-boxes is closed in, does that create a refuge for vermin? If I leave it open and the bees go under there, can I hope that they'll patrol for vermin, and I can leave whatever they decide to build down there (until I take it all out)?