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Coop specific ventilation questions

Discussion in 'Coop & Run - Design, Construction, & Maintenance' started by notiones, Dec 15, 2011.

  1. notiones

    notiones In the Brooder

    Oct 12, 2011
    Big Springs, KS
    I thought I had my coop all figured out, but after reading the following thread, I am more confused about ventilation as ever. Or at least with respect to my coop design.


    For ventilation in my coop I have vents under the eave, a big glass window I can open, and a ridge vent for everything to escape. After looking at the following pictures, can you help me answer these two questions?

    1) How can I tell if humidity is building up in my coop? This morning my coop was 20 degrees warmer than outside and humidity was at 70% (we had a lot of rain the last day or two)

    2) How do I know when to open my big picture window? I don't want to much breeze and with the 4" soffit vents between each rafter and the ridge vent, do I need to open the picture window during the winter? Before I put the soffit in, there was enough draft to blow out a candle even with everything else closed.

    My coop is about half done, but far enough along I can't make any major changes.

    Picture of soffit


    Picture of glass window (actually a re-purposed sliding glass door)


    Sorry if this topic has been re-visited time and time again.


  2. Judy

    Judy Crowing Staff Member Premium Member

    Feb 5, 2009
    South Georgia
    What may make yours workable as it is, is the ridge vent, if it's big enough, moves enough air. The vent needs to be high, preferably the highest point IMO, for ease of escape of humidity and ammonia.

    You could buy two hygrometers if you wanted, and compare coop to outdoor humidity. I think most people can pretty well tell that it's no more humid inside than outside, which, after all, is the best you can do.

    That is a wonderful coop design, granted, but not cheap to build, and must be started from scratch of course, so it's not practical for many.

    Here is what I consider the definitive writeup on ventilation:

  3. cmom

    cmom Hilltop Farm

    Nov 18, 2007
    My Coop
    Last edited: Dec 15, 2011
  4. wyododge

    wyododge Chirping

    Sep 30, 2011
    I had my ventilation figured out, then it got cold and my coop did not move near as much air. Total ventilation failure. We use deep littler and one morning the ammonia about knocked me out. Break out jig saw and wire snips...

    With that said, the only way to know is to get your sniffer in there while the birds are in it. If you smell ammonia you need more ventilation, if you don't, your just fine. Over time it may build up if you are using deep litter, so just keep in mind your practices will develop over time and with experience.

    As far as breezes directly on the birds, they are designed to roost in a tree. Any more protection than that is a plus. I always choose to INCREASE ventilation even if it means a breeze will blow through. Air quality is much more important. We have put our birds in an unnatural environment (coop). The best thing is to get as much fresh air in there as needed to keep air quality good. If that means opening the window wide, and putting a towel in front of it to keep the driving snow out, then that is what it takes. What you don't want to do is have no breeze then all the sudden in January the windows open up full. Start full open, then bring it down slowly.

    FWIW it gets cold here -38* last winter for over a week, -20 and -10 are common, almost daily during late dec through feb. I have a neighbor in town who raises birds in a two sided coop, just to block the wind. He has remarkably healthy birds. I use that as a base line. I have a window on the north side that I had to cover, if I don't the coop will literally fill up with snow. the birds don't really care, I just don't want to chip ice out of the inside of the coop twice a month.

    As far as humidity, it will always be a bit higher than outside humidity (unless they are in a screened cage). A coop with good air quality, will have a relative humidity very close to that of outside.

    The best way I have ever been able to tell is with a good strong sniff as I open the door to let them out. Trust yourself, so far you have done an EXCELLENT job!!!
  5. ECBW

    ECBW Songster

    Apr 12, 2011
    Have you thought about gable vents?

    I have gable vent on either side and soffit vents on the other sides. All have flaps and can be closed if wind is blowing in the its direction.
  6. Fred's Hens

    Fred's Hens Crowing Premium Member

    If you have a ridge vent and with those eave soffit vents, as shown, you're doing about all you can. Sure, you "could" leave the window open as well, but with the huge eave soffit vents and a ridge vent, you're golden.

    The best one can do, as Judy said, is match the outside. Unless one wishes to run a de-humidifier, which would be exorbitant, matching the outside humidity is all one can do. We use outside air, we pass it into the coop, we allow it to exhaust, hopefully taking the birds exhaled air moisture and poop moisture with it on it's way out. That is ventilation. If we move enough air through the coop, we match the outside humidity. That, again, is the best we can do.
  7. Yay Chicks!

    Yay Chicks! Songster

    Apr 15, 2010
    Forest Grove, OR
    Generally the window doesn't count for ventilation, as you don't want it open on cold nights creating a draft. A clue to humidity building up would be condensation on the inside of the window after they've been in the coop all night.

  8. Fred's Hens

    Fred's Hens Crowing Premium Member

    Yay Chicks! :

    Generally the window doesn't count for ventilation, as you don't want it open on cold nights creating a draft. A clue to humidity building up would be condensation on the inside of the window after they've been in the coop all night.

    [​IMG] Absolutely. If the interior window is fogging, it is a sure sign. Sometimes this can mainly be caused by the coop being warmer inside than the outside air. Warm air holds more moisture than cold air.

    And not to open a can of peas on heating, but this is why trying to hold heat inside the coop seems futile to my thinking. I see no way of moving adequate cubit feet of air for ventilation while trying to hold heat inside. I've not wrapped my mind around that yet.

    Here's our barn. It doesn't have a ridge, so no ridge vent, but the principle remains. Air enters through wide open eaves on both sides. It exits out the wide open eave overhang at the highest point, some 16 feet high. It is sited to work with our prevailing winds, which are westerly.

  9. notiones

    notiones In the Brooder

    Oct 12, 2011
    Big Springs, KS
    Thanks for the excellent replies. I feel a bit better now and with what I have gathered from this topic I will do the following.

    1) Leave window closed during the winter.
    2) As I always do, stick my head in and take a whiff to see if I smell anything. If I do, then I may remove the soffit to allow more air to flow.

    My routine is that I go down in the morning to open the pop door, but before I do I open the people door and sprinkle some BOSS into the coop so the hens will keep the litter stirred up. In the evening when I go down to close the pop door I usually stick my head into the coop and make sure it doesn't smell and say good night to the birds and smile at their reaction. It sounds like as long as I keep doing this I will have a pretty good idea of the air quality in the coop.

    I put the soffit up with screws rather than nails so I could remove it if necessary. Wow, I am glad I did. I know if I remove those there will be more than enough ventilation.

    Again, excellent replies all and exactly the info I was looking for. Thank you.

    edit: so far no fogging on the inside, but in the picture above where the window is propped open there is fogging on the outside of the window. That is the only time I have ever seen that. Egg output fell by half when I opened the window and jumped back up after I closed it so I take that as a sign to keep it closed until Spring.
    Last edited: Dec 16, 2011

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