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Condensation season planning — quilt boxes and moisture boards, or the Derek Mitchell insulate-the-top approach?

Perthshire, seven years in, and every autumn I re-litigate moisture strategy with myself. The traditional camp: quilt boxes of wood shavings or a moisture board under the roof, absorbing and venting water vapour so it never drips on the cluster. Cold damp kills, so get the damp OUT. Then there's the argument from Derek Mitchell's work (the Leeds engineer who's published on hive thermodynamics) — that tree cavities are far better insulated than thin wooden hives, and that with serious insulation ON TOP, the warmest surface is above the cluster so condensation happens low down on the cooler walls instead, where bees can actually drink it in winter rather than being dripped on. In that model you don't vent the heat out at all; the 'condensing hive' keeps it. I've run shavings quilts for years and winters fine. But I insulated two roofs heavily last year, no quilt, sealed crown board — also fine, and they were noticeably quicker off the mark in spring. Anyone run both side by side longer than one season?
#condensation#insulation#quilt-box#overwintering
▲ 12 votes 💬 5 replies
5 replies
AlpineCarnica · Aug 29, 2026
I moved my whole operation to the second model years before I knew there was research attached to it — in Tyrol everyone's grandfather already knew a thick warm lid and cold walls beats a ventilated roof. 18 winters: condensation forms on the walls and outer frames, cluster stays dry, and the spring buildup difference you noticed is real and repeats every year. The one rule: the top must be genuinely the warmest surface. Half measures — a thin foam sheet over a vented crown board — give you the drips people blame on 'sealed hives'.
DrentseBij · Aug 29, 2026
I'll defend the quilt box: in a Drenthe winter that's more wet than cold, my shavings quilts take up an astonishing amount of water and the bees winter dry. I don't disagree with Mitchell's physics — a tree trunk it is not, my kit is 20 mm pine — but the quilt is the cheap retrofit that works with the equipment I actually own. If I were buying new I'd buy thick poly and skip the quilt.
BethsBees · Aug 30, 2026
Ontario second-winter question: if I go the insulated-top route with a sealed crown board, do I keep any upper entrance at all? Everything local tells me upper entrance for winter, but that seems to fight the whole keep-the-heat idea.
AlpineCarnica · Aug 30, 2026
BethsBees — that is the eternal argument and honest people disagree. My hives: bottom entrance only, insulated top, no upper hole, and no problems. But my winters are dry cold. In lake-effect damp some keep a small upper notch as insurance. If you insulate properly the notch costs you less heat than a wet cluster would, so it is not a crazy compromise for a second-year.
PerthshireBees · Aug 30, 2026
Running six insulated-sealed and six quilted this winter then, properly side by side, and I'll post spring buildup notes. AlpineCarnica's 'top must be warmest surface, no half measures' is going in my notes verbatim.
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