Bee space is the space between hive part that the bees will allow to be kept clear and open.
- Space ranges between 6.4 mm and 9.5 mm (1/3 an ¾ of an inch).
- Spaces less than 6.4 mm usually gets filled with propolis and spaces greater than 9.5 mm get filled with comb.
Measurement range of bee space is explained well at this link to a web page by David A. Cushman: Bee Space.
Bee Space and Hive Boxes
Hive boxes must be designed so that when two boxes are stacked together there is bee space between the top bars of the lower box and the bottom bars of the top box.
There are two ways to achieve this. To put the bee space at the top of the box or to put it at the bottom of the box.
In Fiji most beekeepers use bottom bee space boxes.
Top of the bottom bee space box. (Fiji, New Zealand)
It is important not to mix these two types of boxes.
Mixed one way and the bees will glue the top and the bottom frames together with popolis. The other way the bees will fill the space with comb.
In either case the beekeeper will have a hard time separating the boxes.
http://www.dave-cushman.net/bee/bsp.html