The concept you’re discussing here of placing the brood box under the existing brood box is common in Warre beekeeping, and is colloquially called ‘nadiring’. This isn’t unheard of with the Langstroth hive as the management process isn’t necessarily linked to the hive style/design.
There are several downsides to this approach, some examples are:
- As you have mentioned, adding a box to the bottom requires additional lifting boxes or essentially disassembling the hive to insert the box. Warre owners have devised all manner of mechanical hive lifts/assists to lift the boxes to achieve this goal.
- If you are using a queen excluder, this will also need to be moved down otherwise you are expanding the brood nest, you also run the risk of placing the queen above the excluder when you move it, so locating the queen and ensuring she is below the excluder adds work to the process.
- If boxes are moved up from brood to honey storing supers they still contain the cocoon and faeces from the brood rearing process trapped in the cell walls. This potentially leads to some contamination of the honey extracted from the super (specifically if it is crushed/strained or pressed from the comb).
- Adding the box underneath is adding a cold/cavity below the brood. One of the concepts of the stacked/vertical hive is that the heat rises. In this case the new empty combs/box won’t be warmed/heated as effectively by the existing hive/comb.
In my experience, I have tried this approach and it wasn’t very successful. They were very slow to draw the comb in the box underneath and it didn’t really provide any benefit. I am only a sample size of one though, so if you do experiment with this, please let us know your results!