Winter ventilation without drafts
Why winter coops need more airflow than most keepers think, and how to keep it without chilling roost-height birds.
The instinct in November is to seal every gap. The instinct is wrong.
A sealed winter coop traps moisture from breath and droppings. Humidity climbs. The birds end up wet, and wet birds frostbite long before dry cold birds do. Frostbitten combs and toes are almost always a humidity problem, not a temperature problem.
The fix is layered. Keep the high outlets fully open above roost height. Reduce, but do not close, the low inlets. The inlets must stay below roost height so cold air does not blow across the birds. Aim for about 1 CFM per bird of slow exchange. Most keepers get this by leaving a gable vent or ridge vent permanently open year-round.
Two visible tests confirm it is working. Look at the ceiling first thing in the morning: no condensation means moisture is leaving. Look at the bedding in the corners: dry means airflow is reaching the floor.
Calculate your specific winter vent area on the homepage by selecting the cold-winter climate.