Van,
"Mr. Jim: {makes a big difference} Jim, are you talking insulation all year, or just summer??? Yes my tops are plastic insulated."
I used to just use the insulation in the STB during the winter. Then one hot spring day, after removing half of the STB insulation boards, I noticed that about half of the hives were bearding. That is when I found out that the ones with the insulation boards, especially the ones with the top insulation board and the STB insulation boards were not bearding. Now I keep them both on all hives all year long and rarely have bearding. When they start to beard, I know they need more room.
Jim