Chicken coop ventilation (UK): stop damp, ammonia, and respiratory misery
A coop can look lovely and still be unhealthy if it traps moisture. This guide shows where vents should be, what “draft-free” really means, and how to fix condensation fast.
What “good ventilation” means
Fresh air exchange without a cold stream of air blowing directly onto sleeping birds.
- vents high up (warm moist air rises)
- airflow above roost height
- dry bedding by morning
Signs you need to fix it
- condensation on walls/roof
- ammonia smell when you open the coop
- wet bedding or damp corners
- hens sneezing/coughing (don’t ignore)
If you notice ammonia: clean today, fix airflow this week.
Myth: “Close vents in winter”
Cold air doesn’t cause the main issue — damp air does. In UK winter, trapped moisture is common and makes birds colder long-term.
Where vents should go
Think “chimney effect”: warm moist air rises and exits high.
- High vents on two sides are ideal (cross-ventilation).
- Keep openings above the roost line.
- Use covers/baffles so rain can’t blow in.
If your only vent is a little gap near the floor, that’s not ventilation — it’s a draft.
Draft vs ventilation (simple test)
At roost height, would you feel a steady breeze on your face? If yes, your vents are too low or too direct.
Fast fixes
- add a baffle over low vents
- open high vents wider
- raise perches if needed (without blocking airflow)
Condensation: the UK winter classic
If your coop is wet inside in the morning, something is wrong — fix it before it becomes a health problem.
- remove wet bedding (don’t “top up” over it)
- increase high ventilation
- check roof leaks / rain splash
- use a droppings board to reduce moisture load
- easier cleaning access (you’ll do it more)
- smooth surfaces (less damp trapped in cracks)
- roofed run area (keeps litter drier)