Who uses slatted racks and why?
Here are a few of the reasons I use slatted racks:
1. Play for bees to hang out and not beard the front of the hive which restricts access by foragers.
2. It provides a thermal layer of air between the bottom of the hive and the brood chamber which aids in overwintering.
3. The bars of the rack act similar to a mouse guard.
4. The bees can use the rack as a work platform when circulating air throughout the hive when cooling, warming, or evaporating moisture.
5. I provides more space between bottom board and brood chamber, thus varroa mites have a harder time reattaching to other bees when they fall off.
There are a few more reasons, but my brain is tired so I can't think of them right now.