Yet another ventilation question

Discussion in 'Coop & Run - Design, Construction, & Maintenance' started by Finnie, Nov 8, 2014.

  1. Finnie

    Finnie Chillin' With My Peeps

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    I've been able to get most of my questions answered by searching other people's topics, but I would like to get some feedback on what other people would do in my situation.

    It sounds like I should have 1sq ft of ventilation per chicken, but for my small coop, it seems like that would be all openings and barely any wall! (It's a 4' x 4' coop, with a fairly low ceiling, about 30" on the high side) Each side will have either a door or a window, but in the winter I figured I would have the shutters and doors to those closed. What I thought I would do for "roof vents" is to leave small gaps between each of the rafters, where the siding would not go all the way up to meet the roof decking. I just have to decide how large those gaps should be.

    I can fill the spaces with pieces of either 2x4s, 2x3s, or nothing at all. Here are some photos to show the different size gaps those would make. To me, the 2x4 seems to leave too small of a gap, and nothing at all just looks too big. Until I put the roof on, it will be fairly easy to make this adjustment. What size opening do you think I should leave here? (The openings will be covered with hardware cloth.)


    Left to right, 2x4 piece, 2x3 piece, no piece:
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    Scrap piece of wood over the top to help illustrate what the gap will look like after the roof is installed. The low side already has 2x4s in place, but those can be switched out to something smaller if needed.
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    The 2x4s leave very little gap at all:
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  2. Ridgerunner

    Ridgerunner True BYC Addict

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    Don’t get too hung up on hard and fast calculations for anything to do with chickens, whether that is square feet in a coop or run, hen to rooster ratio, or area of ventilation needed. Those are based on certain people’s opinions and experiences but may be for some conditions totally different than your situation. Different coops in different climates in different seasons are going to have different ventilation requirements. They are going to have different air flow patterns and different outside conditions that influence that.

    In Indianapolis summers are going to be more of a threat to your chickens than winter. Heat kills a lot more chickens than cold. For summer I strongly suggest you have something low down that you can open up to get air flow through that. Sounds like you will have that.

    In the winter you need ventilation for two purposes. One is to get rid of the ammonia that forms when the poop decomposes. The ammonia gas is dangerous to the chickens’ respiratory systems but it is lighter than air. Even a fairly small hole at a high point will keep ammonia from building up. Gravity will pull the heavier denser air in which will force the lighter ammonia gas out. You don’t even need another hole for the good air to come in. Gravity will take care of that. Ammonia is easy.

    The other risk is the moisture that comes from the wet poop and their breathing. The danger of high moisture content is that it can lead to frostbite, especially on the combs and wattles. Warm air holds more moisture than cold air and is lighter. Their poop starts off warm but will cool off. Their breath is always warm. There is enough to this that it does make a difference. Plus in a small coop like yours, the chickens’ body heat will warm the air. Gravity will displace warmer inside air with cooler outside air. Openings up high work well.

    One other thing to consider. Chickens can handle the cold so well because their feathers trap tiny bits of air in the feathers and down. Those trapped tiny bits of air is what really provides the insulating effect of the feathers and down. If a breeze strong enough to ruffle their feathers and allow those bits of air to escape, they lose a lot of the insulating effect. In the summer that is a good thing but in winter you don’t want a strong breeze hitting the chickens, especially when they are on the roosts. A normal way to handle that in winter is to have a couple of openings up high over where they roost so you get a cross breeze to exchange air but the chickens are under that so their feathers don’t get ruffled. As long as a breeze does not ruffle their feathers you can’t get too much ventilation even in winter.

    What would I do with your coop? With a 30” height at the peak, that’s rough. I’d position the roosts higher than the nests and probably back toward the low end. It looks like you plan to have the low end and both sides totally closed off in the winter so that will create a cul-de-sac or protected area with the only air movement taking place at the high end. Then I’d cover that open area on the high end with hardware cloth to keep predators out. I would not put a 2x4 or 2x3 in there, leaving it as open as I could. I think that will work for you. Good luck!
     
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  3. tcstoehr

    tcstoehr Chillin' With My Peeps

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    How many chickens are you planning to put in there?
    Leaving the inter-joist gaps completely open would not be too much ventilation.
    What I personally would do is leave the entire wall above the nesting boxes completely open. Covered with hardware cloth *and* some 1"x2" welded wire. Alternatively, do that with your own choice of one of the remaining three sides. Wouldn't it be nice to be able to see their little faces without having to open a door. I kinda wish I had done that with my coop so my nightly head-count would be easier.
     
  4. Finnie

    Finnie Chillin' With My Peeps

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    That is my basic plan, but with a hinged shutter attached over it, so I have the option of opening or closing the window.

    The opposite, shorter wall will have a similar window. There will be doors on both of the other sides

    So you and Ridgerunner both agree that I should not block the spaces between the rafters at all. That seems like such a large opening! Does that apply to the low end as well as the high end, or would it be OK to keep the 2x4s in the low end?
     
  5. Ridgerunner

    Ridgerunner True BYC Addict

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    Because your coop is so short I think you may have problems keeping your roosts below the air flow if you leave the lower section open. I'd block the lower one in the winter.
     
  6. JanetS

    JanetS Chillin' With My Peeps

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    This is our ventilation.
    [​IMG]
     
  7. tcstoehr

    tcstoehr Chillin' With My Peeps

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    Quote: Definitely block the spaces between the ceiling joists. Otherwise it's an easy raccoon or squirrel entrance.
    On my coop I did it by attaching 2x4 pieces on edge between the joists secured by 3" screws from underneath. I didn't have much other choice due to my own carpentry mistakes.
     
  8. Finnie

    Finnie Chillin' With My Peeps

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    I'm sorry, I didn't mean to imply that the ventilation areas wouldn't be covered with hardware cloth. They will be. ;)

    It occurred to me that if I want to change the amount of vent space later, it would be pretty impossible to remove those blocks once the roof is on. But filling the gaps with something if they turn out to be too big could be done.

    And I agree with Ridgerunner that the low end should keep the blocks, since the ceiling will be just above their heads while they roost. So the high end blocks are off, and when the wire mesh is on, it will be something like what Janet S has in her photo.

    Here's how it looks so far without the roof. You can see that there are 2x4s between the joists on the low end, and none at the high end.
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  9. aart

    aart Chicken Juggler! Premium Member

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    My Coop
    I left my eaves open but well secured with HC. Was much easier to put the HC on from the outside and cover the whole eave with on piece.

    Here's some pics, hope the helps:

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