Most TBH comb failure occurs during or after inspection, not before. Ventilation isn't an issue with TBHs when its hot. Ventilation doesn't reduce heat when its already hot outside. Ventilation is more important in wintertime than in summertime. Bees can control heat just fine if you leave them bee. Don't work TBHs for a long time in the noonday sun with the topbars exposed to raw sunlight getting the bars hot so the wax attached to the bar started softening and then failing. Don't remove attachments when combs are brand new white and full of honey. Go ahead and pull the comb, but put the comb back ontop of the broken support burrs so it has the extra support. Don't build giant hives with 25 inch top bars and 20 inches deep. Don't manhandle combs new or old.
I had combs collapse in the summer last year, but each and every time it was my fault now that I look back on it. Once I figured out what I was doing wrong, combs stopped breaking.
What to do and not do:
Remove combs carefully, don't tug on attachments work them loose little by little, no need for coat hanger cutting.
Don't handle fresh comb if filled with honey. Don't remove attachments with new heavy combs.
Work the hive as quyickly as is comfortable and replace cover getting sun off of topbars.
Cradle the topbar when working them, don't grasp them, let gravity hold them the right way.
the list gets longer....
Scot Mc Pherson<br />McPherson Family Honey Farms<br />Davenport, IA<br />BeeWiki: <a href=\"http://beewiki.linuxfromscratch.org\" target=\"_blank\">http://beewiki.linuxfromscratch.org</a> <br /><br />Pics:<br /> <a href=\"http://linuxfromscratch.org/~scot/pics/bees/\" target=\"_blank\">http://linuxfromscratch.org/~scot/pics/bees/</a>