Ventilation in Chicken Houses

The weather has finally started to warm up here in Bedfordshire and we’re now into double digits on the temperature scale. As well as my usual cleaning out this weekend, I have also been opening the vents on my coops to allow a little more ventilation.

Good ventilation in a chicken house has to be one of the most important factors in the design of a chicken house yet so many coops I see either don’t provide adequate ventilation, or don’t provide vents in the right places.

Vents in the apex allow warm air to escape.

Every school teaches children that warmer air is lighter than cooler air which causes it to rise and hot air balloons are good proof of this! Well, it’s no different in a chicken coop at night when the hens are roosting.

Warm, stale air rises from birds and their droppings and accumulates in the top of the coop. A small vent in the apex of a roof allows this warm air to escape and causes fresh air to be drawn in from lower level vents.

It’s this circulation of air that removes ammonia released from droppings. Ammonia can be damaging to hen’s respiratory systems and hens can tolerate the cold so there should be good ventilation in the coop, even during the bitterest weather.

Upper vents of my large chicken house

Ammonia in droppings can be reduced by adding supplements of Garlic or by using charcoal such as Happy Tummy in the diet. How can you tell if there is too much ammonia in a coop? Very easily: Pop your head in through the chicken house door in the morning before letting the hens out and smell. If there is too much ammonia, you will smell it.

Ammonia isn’t the only problem in the coop, the moisture from droppings is released into the air as they dry out, causing humid air which is not only uncomfortable but is also perfect the various pathogens. Damp litter is the perfect breeding ground for E.coli, which is really bad news!


Despite having good ventilation in a coop, it is also true that draughts can be a killer, especially of young ‘growers’, hens that are wet, or that have lost a lot of feathers through bullying or moulting (not forgetting the poor old ex-battery hens).

So what is a ‘draught’ and what is ‘good ventilation’?

Well, I believe the ideal situation is to have small permanent vents in the apex of the coop which is far higher than hens can roost but also adjustable vents below the level of perches. This means hens don’t get a direct draught from either of these vents.

Adjustable lower vent.
A large adjustable vent on my large chicken house facing North away from prevailing winds.

The reality in most chicken houses is that the lower vents end up being about the same height as the perches, however, if this is adjustable, or the coop is orientated such that the prevailing south-westerly winds don’t blow in through this vent, the hens will usually be fine in all weathers.

Apart from young birds that can’t regulate their temperature or maintain it without additional heat, heat is far worse for chickens than the cold so placing the coop in the shade or partial shade will help to keep it cool during the summer months when a coop can hold the heat from the hot afternoon sun right into the evening when birds are roosting.

Whilst this isn’t a possibility for me at the moment, I have planted an orchard for the longer term solution and for now, I ensure the coop can have maximum ventilation on warm nights.

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Tim Daniels

Tim is the founder of the poultrykeeper website and lives in Herefordshire, UK. He keeps Cream Legbar chickens, Silver Sebright bantams and hybrid layers for eggs, Abacot Ranger ducks, Brecon Buff geese and some quail.

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