The bee space is simply the crawl space needed by a bee to pass easily between two structures (7.5 mm +/- 1.5 mm for the western hive bee, less for the eastern hive bee). If the space between any two surfaces in the hive is too small for a bee to pass through easily, the bees willseal it with propolis. If the space is larger than a bee needs to pass through easily, the bees will construct comb in the area.
When the space between two surfaces in the hive is the right size, the bees will leave it free as a crawl space. if the bee space is considered and respected in the construction of a hive, a hive that allows for easy comb removal and replacement will result.