Venting - is it really 1 sq ft of vent per chicken???

Discussion in 'Coop & Run - Design, Construction, & Maintenance' started by samana, May 17, 2011.

  1. samana

    samana Out Of The Brooder

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    Starting to prepare a shed I have into a coop. It is an attachment to a larger shed, therefore the back wall of it can't be vented (where it's against the other building). That is the south side. So I can vent the north, east or west sides. I came across this today:


    "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. "
    (from https://www.backyardchickens.com/web/viewblog.php?id=1642-VENTILATION)

    Can
    anyone vouch that much venting is appropriate? I was thinking of using floor registers, but that would be an awful lot of them.

    I live in west MI - winds not usually bad where I'm at (forested area), but when windy its from the west usually. In summer I will be able to open the big screen on the storm door I'm installing to the front (north side) of the coop for the 'people entrance'. Light will be coming in from that front side through the storm door window and the full length glass doggie door panel I'm restructuring to be the 'chicken entrance'. No light from the east/west sides save for whatever the vents let in.

    Would truly appreciate all your thoughts and suggestions on the plan so far and how I ought to go about the venting. My coop will comfortably hold a max of 22 chickens. It's about 8X11. Will be doing a deep litter method. So far only 9 chickens.

    I'll attach a pic to help - (digging in a deep trench around edge of 1/4"hardware cloth to keep out critters, and putting up osb for more insulation).
    You can see the amount of venting and light they'll get with the storm door and doggie door.

    [​IMG]
     
  2. Pairie Faring

    Pairie Faring Chillin' With My Peeps

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    I don't have an answer for you but I just had to say "Those dogs are adorable!"
     
  3. samana

    samana Out Of The Brooder

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    hahaha [​IMG] - my two old dogs, looking like statue guardians - I can only hope they'll be that way with the chickens [​IMG]
     
  4. Fred's Hens

    Fred's Hens Chicken Obsessed Premium Member

    Venting, vents, and ventilation are words that seem confusing to an awful lot of folks. It isn't that difficult. To install a vent is to provide a way for rising warm, moist air to exit a structure. Think roof venting on your attic. Those vents are there to allow hot air escape from under the roof in the summer, but equally important is that they allow moisture to escape or your house insulation would be soggy and ineffective in the winter.

    Similarly, barn/shed/coop vents are useful if placed at the highest places of the structure. Cupolas are really fashionable. You likely remember seeing early 1900's dairy barns with a huge vents on the roof, because dairy cows exhale huge amounts of water in the breathing.

    Cold doesn't bother chickens, even seriously cold temperatures, but humidity is a real issue. When temps are below freezing, humidity re-forms as frost on the chicken's combs, wattles and feet, those body parts not covered in feathers. Smells, methane gases, especially ammonia also need to be vented. Chicken's expire a lot of water vapor and their poop is extremely wet.

    For air to rise out the roof or cable vents, there needs to be a place at the soffit where there is an air intake. Dry air in, humid, stinky air out. That is what you are after.

    Being able to also seasonally open up the coop to allow for cooling breezes to pass through in the hot summer is also important feature to plan for.
     
  5. Egghead_Jr

    Egghead_Jr Overrun With Chickens

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    There are so many factors when considering your venting/coop design. The biggest being your climate. Texas needs some serious air circulation and shade or insulation for coop to keep it cool inside as outside and that's what? 100F plus in summer? Here in northern New England I use a gabled roof and physics to produce the just over the minimum of air circulation needed and that # is 0.5 cubic feet of air circulated per chicken per minute. Many here are appalled as to how little actual vent area I provide. We don't heat the coop here and had minor touch of frostbite on chickens with largest combs in -30F conditions. My wee coop is on my page with that physics calculation to produce the air circulation of over 0.5 cubic ft per bird per minute.

    So it becomes a situational question. How hot does it get? Chickens can not stand the heat. How cold does it get and what is the prevailing arctic wind direction? Chickens can withstand cold very well. The problem arises if: 1) They cannot get shelter from arctic winds (direct 0 F and under winds due to too large and poorly placed vents). 2) You did not provide enough air circulation so humidity levels get too high. This results in moisture freezing on the combs causing frostbite at 32 F.

    Providing deep liter will keep the coop dryer. In MI your not needing full open side ventilation in summer. Sounds like your doing a convection venting system (warm air rising and venting out). Hold on a bit...I'll do some research as this question comes up all too often and see what the physics is on convection air circulation. Be back in a jiffy!

    Gotta run but this is the formula I'll base an easy answer on when I get back: Q=9.4*A*sqroot of (h(t inside-t out)/t inside))

    Alrighty, got my chores done and can give some empirical data to state "No. There is no need for 1 sqft of venting for per chicken." It would be a worst case and most poorly thought out scenario.

    Let look at some quick numbers:

    If 100F both inside and out of coop and venting is at equal height= 77 in^2 opening for both inlet and outlet vents per chicken (the worse case and improbable to reproduce in nature, yes this equates to 1 sq ft total area vent per chicken)

    This same condition with inlet vent 5 ft lower than outlet vent= 34.2 in^2 opening for each vent per chicken.

    100F outside, 105F in coop and vents same height= 35.1 in^2 per inlet and outlet per chicken.

    Same condition but inlet vent 5 feet lower than outlet= 15.7 in^2 per vent opening per chicken.

    32F both inside and outside coop, vents at same elevation= 43.4 in^2 per vent per chicken.

    Same condition with inlet 5 ft lower than outlet= 19.4 in^2 per vent area per chicken.

    32F outside, 37 degrees inside vents at same height= 20.8 in^2 per vent per chicken.

    In a nutshell: Put your outlets high on the bulding, put an inlet vent lower to ground away from nesting boxes and roosts. HIgh temperatures require more venting and lets face it it will always be hotter in the coop than outside. A 5 degree varience is shown to show how drastic it changes air circulation.
     
    Last edited: May 17, 2011
  6. Judy

    Judy Moderator Staff Member

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    Agree with Fred's Hens, venting needs to be up as high as possible -- warm humid air and ammonia need a way out. I once read where Pat said there does not need to be an intake, that the fresh air will exchange right at the soffit or whatever. Either way, floor vents are probably not where you want fresh air coming in -- too likely to result in a draft on the birds, I would think. It's a tricky balance between ventilation and drafts -- unless all your venting is at the high point of the coop. With one sq ft per bird it makes sense to me there would be plenty of exchange. But then I'm no engineer -- and being in the south I have a lot more ventilation than 1 sq ft per bird.
     
  7. teach1rusl

    teach1rusl Love My Chickens

    Well, the first thing that stood out to me was the comment that 'cold doesn't bother chickens.' [​IMG] I hate when people say that FH!!! But I won't argue that now. I do agree that chickens handle cold weather better than hot weather...
    OP - I don't have 1sq. ft of ventilation for each of my birds, in winter or summer. I have two 8x16 house vents plus two windows, but the windows are closed in the winter time. But I have a small amount of birds for my space - about 9 sq. ft each of indoor space, AND I clean poop daily (I use dropping boards), so moisture doesn't build up, even in winter, when the windows are kept shut. I will say that for summer time, I really regret NOT having more ventilation, because it can always be covered up in severe weather, but it's a pain in the butt to try to add vent. after the fact. Anyhow, less ventilation is doable if you're vigilant. With deep litter, I don't know if that's doable??? I would think quite a bit of moisture would build up with collected poo...
     
  8. JackE

    JackE Chillin' With My Peeps

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    I'll mostly second what Fred said. Chickens don't seem, to me, To mind the cold. During last winter, That wind would be howling around, I'd go out to check on the chickens. They would be hanging out by the front screen wall watching the day go by. They did not like walking in the snow, but cold weather in itself, did not seem to bother them. Go with more ventilation than you think, and you'll be better off. And more importantly, your birds will be better off.
    Jack
     
  9. Fred's Hens

    Fred's Hens Chicken Obsessed Premium Member

    Different folks have different experiences and I respect that. It's ok to have different points of view of cold and chickens. What is cold to someone who lives down along the Ohio River, someone who lives in Mississippi or someone who lives up here half way to the North Pole is often different.

    That said, I respectfully offer some caveats, for what it is worth. Those who do live in very cold climates, such as northern Michigan, should consider cold hearty breeds. These traditional breeds were created over a century ago in cold, snowy places such as upstate New York and New Hampshire. Rocks, Wyandottes, RIR, NH, etc, etc. They have been kept for well over a century in unheated coops and barns successfully and have thrived or we'd not have them today.

    The OP is from western Michigan and cold is simply going to be a fact of life. What does not have to be accepted is humidity/condensation, and frostbite due to it, or drafty winter shelter for chickens. I wish the OP the very best in designing a practical, safe, healthy and secure coop.
     
  10. patandchickens

    patandchickens Flock Mistress

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    Can I point out an important distinction, maybe I need to rewrite my ventilation page to be clearer, I dunno.

    There are TWO DIFFERENT issues. One is how much ventilation you BUILD, i.e. the maximum the structure is then capable of having open. The other is how much you HAVE OPEN at any given moment in time.

    In wintertime, the second number will often be less than the first number, at least for the types of coops BYCers usually build.

    It is a free country. If you want to build a coop with very little ventilation, fine, go for it. Chances are you will see, within the year, why more is recommended, and then you can go back and cut out more. It is a lot easier in my opinion to design it in *in the first place* when you're building your coop, but, <shrug>

    BTW, for wintertime you may want to vent *into* the larger shed your coop is attached to, unless there is some important reason you can't (dust-sensitive machinery in there, or wall can't easily be cut thru, etc). That is actually quite a nice setup for wintertime as it allows you to keep cold winds totally out of the equation when you want to.

    Good luck, have fun,

    Pat
     

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