Chicken Coop Ventilation - Go Out There And Cut More Holes In Your Coop!

Why is ventilation such a big deal? Because chickens are amazing producers of moisture, ammonia and heat, that's why.
By patandchickens · Jan 11, 2012 · Updated Dec 7, 2014 · ·
  1. patandchickens
    Go out there and cut more holes in your coop!
    Now! Really truly!


    Why is ventilation such a big deal?

    Because chickens are amazing producers of moisture, ammonia and heat, that's why. Small but mighty! (Mighty messy anyhow).
    1) Ventilation removes dampness and humidity from the coop. Chickens generate scary amounts of water vapor, partly through breathing out (same as we do, that's why a mirror fogs when you breathe on it), and largely through pooing (chickens do not urinate as such - all the water they would be peeing out if they were any other sort of animal is contained in their poo). They process a lot more water than you might think. All of this water tends to make the coop air humid. High relative humidity (especially in cooler temperatures) makes chickens more susceptible to respiratory disease and increases the chance of frostbite. Chickens can stand considerable cold without frostbite if the air is dry; not so much if the air is clammy.

    2) Ventilation removes ammonia fumes from the coop. Unless you sit there all the time, ready to whisk each plop of poo away to the compost pile the moment it comes out of the chicken, there will be some ammonia being released into your coop's atmosphere. It does not take all that much ammonia to cause subclinical damage to the tissues of the chicken's respiratory tract, which makes the chicken more vulnerable to any respiratory 'bugs' that may be floatin' around the environment. Basically if your nose can smell ammonia, there is enough of it to be harmful to lung tissues.

    3) Ventilation usually helps keep the coop from getting too hot in summer. Chickens' bodies perform best below about 75 degrees F; over 90 F they start to have real problems, suffer heat stress, and if it gets too hot they can die, especially larger-bodied and heavier-feathered breeds. Proper ventilation will at least keep your coop from getting any hotter than the outside air.

    When do I need ventilation?
    Always. Yes, even in cold weather. Yes, even in northern cold weather. Realio trulio. There may be a night now and then when it's so vastly cold you close things down, or if you're having a hurricane you may close the vent flaps and windows so that the weather stays outdoors, but those sorts of things will be rare exceptions, not the rule.

    Types of ventilation
    Passive (natural) ventilation means that you have openings that air flows through with no help from you or the power grid -- just the natural action of wind and the tendency of warm air to rise. Passive ventilation includes an open window, a ventilation slot, a louvered gable-end vent, that sort of thing.
    Passive ventilation is the easiest, cheapest, safest, and most foolproof method for the vast majority of backyard coops, in my opinion. Build lots of it.
    Wind turbine ventilation means those spinning turbine things, about the size of a basketball, that you mount on a building's roof. When the wind blows, it spins the blades and they suck air actively out of the coop. This can move a goodly amount of air, but only if the wind is blowing. When the wind stops, it becomes a smallish hole in the roof, period.
    Active (mechanical) ventilation means using an electric fan, generally plug-in although small solar powered units do exist. This allows you to get greater air movement with smaller holes in your coop walls, but with several important drawbacks. You really ought to get a fan designed for dusty and outdoorsy environments (designed for barn or workshop use), which costs more - a house fan will very quickly clog with dust and stop working or die altogether. Even appropriate fans need to be cleaned regularly or their performance becomes poor and they can become a fire hazard. Also, if your power supply fails, so does your coop air quality (solar units usually run only when the sun is actually shining on them, so are no use at night).
    Opening the door a couple times a day to walk in and out of the coop does not count as 'ventilation', sorry.

    So how much ventilation do I need?
    More than you probably think. More, proportionately speaking, than you're used to seeing on a house, or doghouse, or garden shed, or things like that. It is really impressive how much water vapor (as well as ammonia and heat) even just a chicken or two will emit, round the clock, day in day out.
    So the best answer is probably "as much as (or slightly more than) you can reasonably build". Honestly, that is the simplest, easiest, most foolproof way to go. It is ever so much better to have more than you need than to need more than you have! Especially if "needing more than you have" comes down to a trip out back with the reciprocating saw to hack big ugly holes in your nice pretty trimmed-and-finished coop in the depths of January. Plan ahead.
    If you really want me to suggest numbers: if summer heat is not a big problem where you live, then you will most likely be fine if you build at least 1 sq ft of vent opening per chicken, or (if you want a lower but therefore less-conservative number) 1 sq ft of vent opening per 10 sq ft of floor area. In a hot area, you will need more for summertime, possibly just having one or more walls being totally hardwarecloth. If you have unusually few chickens for your size of coop, or live in a very dry area, you may be fine with less ventilation; if your chickens are very crowded, your climate wet, your coop full of poo, or the bedding is wet for any reason, then you may need more than the above numbers.
    All vents should have doors/flaps/covers/what-have-you so that parts can be closed down when not desired. Unless you're in a climate that stays fairly warmish year-round, covers should be draft-proof. Either they should fit very snugly, or be weatherstripped in places the chickens can't peck, or (sometimes simplest) the ones you're not going to ever use in cool weather can just be "decommissioned" at the end of the summer, panels bolted over them, and any gaps sealed til Spring in some manner the chickens won't peck at. In areas where cool weather is not all that cool and only lasts a few months, you can reverse the concept -- just build one or more walls entirely of wire (on studs) and simply cover 'em with plywood or plastic for your so-called winter.
    If you live in a hot climate, you need large areas of ventilation that can be opened up on all 4 walls, and really it is best if one or more walls can be pretty much removed entirely so they're just screen (like hardwarecloth). In a climate where it never gets really all that hot, you can probably skip the whole-wall-coming-off part... unless you are in a desert-y area with giant temperature swings from day to night, in which case you may still want something of that sort. But even up North it is far-and-away best to have the ability to fling open the hatches and get lots and lots of fresh air. If nothing else, this will be of great assistance to you in drying the coop out if you should ever find yourself needing to hose down or disinfect the inside!
    Securely screen your vents, whatever the size, with something like hardwarecloth that predators can't rip off, climb between, or grab handsfulls of chickens through.
    "What if I just use a hole-saw to put a buncha 2" holes in the walls and screen them, that'll be good, right?" Unfortunately, a 2" diameter hole is about 3 square inches of total area. To put this in perspective, a square foot is 144 square inches. You would need almost 50 holes to equal one square foot of ventilation, and a typical coop is going to need MUCH more than just one square foot of ventilation! So, no little round holes. You want actual decent-sized openings, like 6" x 4' or 1'x3' or like that, on most if not all of the walls.


    Ventilation yes: drafts NO
    While ventilation aka air exchange is necessary and good, having cold air aimed right at your chickens is BAD. (I'm talking about in cool weather, here, not your 'pleasant cooling breeze on stifling August day' which would of course be good.) Small "air leak" type gaps can also cause condensation and frost, which nullifies much of the value of what ventilation you have. So you need to design your ventilation intelligently.
    Ventilation that you'll be using in cool/cold weather (i.e. all year-round) should be high up above chicken level, at the tops of the walls, ideally protected from rain and wind to some degree by roof overhangs. You can put vent slots, long and relatively narrow, atop all four walls. (By narrow I mean like 4"-8" wide or something like that, not an inch or two width of 'arrow slot', unless it is a small coop for just a couple few chickens.) Vents near the roost are good in hot weather but bad in cold weather. Ask yourself "will a chicken experience a noticeable breeze on the roost in the winter?" If yes, arrange things so you can shut down those vents when temperatures drop.
    You'll want additional ventilation for warmer weather, that can (should!) be lower down where the chickens can catch some breeze. Windows work; giant removable wall panels work; that sort of thing.
    Do the coop 'people door' and pophole count? Sort of. I mean, yes, they do provide ventilation when they are open, but remember that they will not always be open and you need to be able to provide sufficient airflow even when they aren't. I would not suggest counting on them towards your basic ventilation needs.
    Manage your ventilation intelligently -- you will want to change the amount that's open according to the weather, although as mentioned you don't want to shut it all down except in very rare instances. Sometimes you'll want to close upwind vents if it's getting too windy in the coop on a windy day.
    In a really windy site, you may want to build some sort of baffle or hood for some of the usually-upwind vents (the high year-round ones) to blunt the force of the wind.

    What about winter? Don't I need to close the vents to keep the chickens warm?
    NO. Well ok, yeah, you will close some of them down, relative to summer conditions; but you still need a goodly amount of air exchange going on, so you cannot shut your ventilation off.
    In some ways ventilation is actually more important in winter because cold air can't hold nearly so much water vapor before it gets saturated i.e. really damp and humid and clammy, i.e. you're trolling for frostbite and respiratory disease.
    So yes, your vents will be letting in cold air, but you know what, that's OK as long as it is not breezing down directly at your chickens. If you're concerned about the chickens getting too cold -- although most standard-sized breeds are fine down to freezing and significantly below, as long as the air is dry and relatively still and they have an appropriate-width roost and plenty of food -- then insulate your coop. And yes, insulation is quite useful even with vents open (for some reason this issue comes up often); would you think it pointless to wear a winter coat just 'cuz you had no hat on? :p What insulation does is reduce heat loss from the coop so that you can afford to admit more cold air without making the place too cold.
    In a super-cold climate, and let me say that I do not consider southern Ontario Canada where I live to fall into this category (!), you may want to think about arranging for your vents to be taking air in from a somewhat thermally-buffered source... a predatorproofed flue run along the ground a ways and covered in insulation, or a translucently-enclosed space that the sun warms, or the building's attic, or a larger barn, or like that.

    Some links with useful further information about ventilating chicken quarters:
    They're mostly aimed at big commercial barns (poultry and otherwise), but there is a lot that applies just as well to our little backyard coops, so take a look:

    Check out this great discussion with pictures: Do I have enough ventilation?

    Coop & Run - Design, Construction & Maintenance Forum Section

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    N F C, MayaB, mudgrl92 and 21 others like this.

Recent User Reviews

  1. Tara Bear
    "Thank you for the education!!"
    5/5, 5 out of 5, reviewed Jun 1, 2019
    Fantastic information that is explained clearly!! The article covers so many questions I had about ventilation. Thank you.
  2. Trux
    "Great Read"
    5/5, 5 out of 5, reviewed May 23, 2019
    Thanks for posting! Very informative for all levels of us chicken keepers:thumbsup It is also a subject that needs more attention apparently, as people don't realize how important ventilation can be to the health of your flock.
  3. tlatham72
    "Very Informative & Organized Presentation"
    5/5, 5 out of 5, reviewed May 14, 2019
    Thank you for this article. I'm trying to design my first coop for my first flock of chickens (to come). Ventilation is one of the topics I've been confused about still. You did a good job of explaining the difference between ventilation and a draft and the types of ventilation and ways to add ventilation to a coop. Specifically, I now know how to work some specific ventilation into the coop design to be used in the summer months. I do still have a question or two about summer -- generally, what do you do for ventilation at night? My instinct is to close up the windows and other ventilation that is down low for extra safety from predators, but it seems like I may need to leave the additional ventilation open even at night. Thoughts anyone?

    I plan to have 4-6 hens purely for pets. I'll, of course eat their eggs, but egg production isn't my primary goal. Since they will be like part of the family (hopefully) and since I live in the country, I'm crazy worried about predators and plan to go to the greatest lengths in coop design to keep them safe. So the thought of lots of open ventilation at night frightens me. I know it should all be covered with hardware cloth, no open holes, no large holes, but is this enough? Or can I close up the ventilation not near the roof at night? I, of course, want them to be cool and comfy. Maybe I should include insulation in my coop walls? Or a fan? I swear I'd even add an AC if it kept them safe from predators. LOL

    I live in northwest (upstate) South Carolina. Summers get very hot. 90s. And usually a week or few days here and there in August that may hit very high 90s or slip over 100. My coop and run are going to sit off the edge of my back yard into the edge of my woods in a small clearing that is very shaded. My coop and the attached run will be about 9-10 ft tall. The run will be wood frame and hardware cloth with a shingled or metal slanted shed roof.

    Again, fantastic article. Before reading, I had pretty much no understanding of ventilation other than I needed it.


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  1. Tough Old Bird
    Now that was an education and a very worthy read for someone like me who is currently designing my first coop. THANKS.
  2. Sally Sunshine
    Great Article wish I had seen it BEFORE I built our coop!
  3. upitty
    I just made three whopping great big holes beneath the roof of my coop. Got some great airflow going now and I migh put a couple more in on the other side. A bit of mesh and a staple gun fixes everything!
  4. Green Lantern
    Thanks Pat! I really appreciate you taking the time to be so clear on this. I knew vents were important but had no idea how much would be "enough". Thanks for taking the time to write such a well written post!!!!
  5. nashvillechick
    Great information, but I have one question: What's an appropriate width roost? Four inches? Is it so they can sit on their feet to keep them warm?
  6. Scooter&Suzie
    Oh wow... I'd better go get an ax and make a few holes... (Just kidding, I'll do it a bit better than that!)
  7. farmerfogg
    Very nice article! Thanks for the information!
  8. LeJeune1
    Thanks for the Info. Same question as ABarb, regarding winter temps.
  9. jimandscott
    hhmmmm? we get to -15 degrees C... ? and need to put vasilean on there combs and wattles.. is that cold enough to do a full lock down?? i clean out EVERY morning to prevent amonia build up. and they are shut up completley every night.!!! the coop is open through the day till they go in themselves at nightfall.
  10. trac
    The property that I own has been in my family for a couple of generations. My Grandparents lived here, my parents lived here and now it is my property. There is a chicken coop that was used through these years. Originally it had two doors, and about six windows. Through the years the coop outside was covered up with metal and all the windows were covered and one door. I have laying hens in this coop and have had problems with colds. I have opened one of the windows and there are future plans to open the door and another window back up. With this article, I have reassured myself that I was right about opening more holes!!! Thank you from me and my chickens!!!
  11. jackieambrose
    Great article about coop ventiltion, I am new at keeping chickens and I now know my chickens (3) don't have enough ventilion. Get hubby onto it tomorrow. Thanks again
  12. mg15
    Best article on ventilation, thank you.
  13. NanaRose
    After reading an article, from a writer in the North, about having an 'open' coop, I decided to make the large west door of my small coop hardware cloth. I've been delighted with how airy our coop stays here in south Alabama. Best thing about our hen house is the air flow. Never have an odor or fly problem. Today hurricane Isaac is pending, so we put a cover over the top half of the door to ward off the over-abundance of rain. But normal rain is not a problem.
  14. CollegeChicks
    My husband is planning a Texas Coop and this article will get the ventilation right the first time. Great job, it covers it all!
  15. sunshinestatechickens
    This is such important information, especially here in Florida. Could you possibly add a picture so that I could pin this to my Pinterest board for all my chicken people? I see so many people down here with closed up coops that I would like to get this info out there in as many ways possible, but I have to have a picture in the article in order to pin it. Thanks so much.
  16. cherylkanuck
    very informative. We have only had our chickens a little over a month and it seems we have enough ventilation but Thinking now about adding a bit more for good measure. thanks so much for such great info.
  17. pollitaroja
    My chicken coop is actually a dog run and is airy all around. For chicks I keep them in the florida room till old enough. Our winters are 30 degrees some nights, but not for long.
  18. markop50
    Feeling good now, I am building my coop now and was wondering if I had too much ventilation. Thanks for the very informative and entertaining article.
  19. gjensen
    A lesson I have learned is where that ventilation is matters almost as much as how much. Consider your prevailing winds. A natural breeze through the house in the summer is great. Openings on opposite sides in line with each other helps.
    If all of the ventilation is 3 to four feet off of the floor, the air can still get stagnant near the floor. That is where the birds are. Ventilation near the floor with a ventilation at the roof creates its own draft as the heat rises. Cupolas are great. Think high and low.
    One of the challenges I have had is balancing ventilation and dry from the rain. I have went back and installed some overhangs over windows that are on the side we generally get our blowing rain from.
    Another challenge I have is letting some sun in, but always providing some shade. I have a variety of houses and they each have had their challenges.
    Cold, other than keeping the wind off of them is not a concern here.
      CoopdeVillage likes this.
  20. ldel4567
    Thank you!
  21. ABarb
    Lots of great info. Thank you.
    Perhaps this is a silly question, but... does including a lot of insulation to protect the birds from cold winters while allowing for plenty of ventilation (I live in midstate NY) make the coop hotter in the summer? We have long and cold winters but it does get very hot for our short summer. Thanks so much!
  22. awesomechicken
    this is going to help a lot when i build my coop.
  23. willowbranchfarm
    This is great. Good job.
  24. BYC Project Manager
    Congratulations, patandchickens! Your article is featured on the homepage! Thank you for writing it and sharing it with our community.
  25. Kisska
    Thank you so much for the info!! I have been looking exactly for that!! =)
  26. PAChickenChick2
    I have pasted this post so many times it automatically pops up in my browser Probably the best information out there!
    Thanks so much for posting it. =)
  27. flyfisher
    Good article. We're building a coop this week, and while I had planned for ventilation, I now think I need to think more about how to ventilate the coop in the winter.
  28. Rvl Rookie
    I put a vent and a window in my coop today. Thanks for the great info page.
    This is GREAT information! Thank you!
  31. BeckyC
    Yikes, we have alot to learn.
  32. PulletMama
    Many thanks for the article! My father is building a coop for my girls and he wanted to put more ventilation in than I thought was necessary....ooops. Thank goodness he's not finished yet!
  33. kiwiegg
    You are a bloody genius Pat...thank you!!!
  34. PamelaTX
    Wow! I knew I needed ventilation but I had no idea how much! I will design a LOT of air movement into my Texas coop. Thanks for the article.
  35. CrazyCatCulby
    This is the best article I have read about ventilation so far... I am going outside to cut some holes in my coop!
  36. rjphillipsjr
    This is so helpful. I am designing and building my first coop, and was curious as to the amount of ventilation needed! Thanks!
  37. dmclalin
    Thank you for your information. This has been a great read and will help me confidently add more ventilation to my coop.
  38. t/m
    Thank you for your fun and informative article! It's nice to have all this in one place. I like the forums but we are in the process of our 2nd (much smaller) tractor coop so this was a nice 'refresher course'. I think you covered everything!
  39. ChickensAreSweet
    This page is a classic. I have directed many people to this page to learn about ventilation. Great job Pat!

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