The Great Winter Coop Humidity/Ventilation Experiment! Post Your Results Here!

Discussion in 'Managing Your Flock' started by mobius, Dec 17, 2016.

  1. mobius

    mobius Chillin' With My Peeps

    Hi Everyone!

    I live, with six chickens, in what I like to call Deep Northwest Montana. This is my first winter with chickens. I have had quite a bit of concern over humidity and ventilation in the coop as winter approached. So on good advice on this forum, I purchased a hygrometer/thermometer that does remote readings. I tested it using the salt water test. It was 5% below, so I add 5 to my readings. I put the remote in the chicken coop at beak level where my girls roost. They are winter-hardy breeds.

    So the (tested) hygrometer is my new best friend at the moment. Last night it was predicted to get to -12F here, and ya know what? It DID. So I was rather concerned. In advance. I decided to take readings every half hour last night (and this morning). I am starting this thread to post the results. I encourage any of you who would like, to post your results here also, in the interest of sharing and tweaking.

    Last Night:

    10:30 p.m
    Outside: -8F. RH 71%
    Coop Pop Door Open: 8F RH 64%

    AS the chickens seem to keep the 4x5x5 coop about 10 to 16 degrees warmer, I was starting to get concerned about the -12F. So I called it, and closed the pop door at this point.

    11:30 p.m.
    Outside -9F RH 78%
    Coop 7F RH 64%

    So far so good. It stabilized until:

    1:30 a.m. (Don't tease me about staying up please! Or do, it's ok!)[​IMG]
    Outside -12F RH 74%
    Coop 5F RH 65%


    8 a.m.
    Outside -12F RH 83%
    Coop 4F RH 67%

    9 a.m.
    Outside -8F RH 78%
    Coop 6F RH 67%

    Whew! Okay it is not going to get above zero until noon. While I usually take warm food out to them in the a.m. and usually the pop door remains open, I am going to leave them closed up til about noon and then give them lots of yummy things.

    Other points of note:

    They have food and water in the coop. The water is horizontal nipples on a covered 4 gallon bucket with a stock tank de-icer.
    I slathered their combs with castor oil.
    I put PILES of straw (over regular pine shavings)in their run AND coop yesterday, which they began to distribute.

    I hope this helps folks worried about deep cold! I have had a LOT of good advice on this forum, which seems to be paying off. These results are very reassuring to me (and I hope they may help you)! Please DO post any data you collect!

    I will continue to post readings here myself. Obviously I like to keep track![​IMG]

    HERE is the level we are shooting for and more info about hygrometers (humidity measurers):

    From @patandchickens :

    Yes, you CAN get indoor humidity lower than outdoors, if your indoor is warmer (I am not advocating electric heating necessarily -- there are LOTS of things that can act to make your coop warmer than the outdoors, esp. at night. See 'cold coop' page in .sig below for that subject). What matters in terms of frostbite is relative humidity. For a given amount of water vapor in the air, relative humidity is lower at warmer temperatures.

    Also, in terms of temporary weather 'blips', it sure seems to me like having your coop start out pretty dry -- dry wood, dry shavings, nonpooey, nonhumid -- seems to create a sort of 'humidity sponge' that can even out temporary swings in the weather.

    Commercial chicken barns seem to aim for around 50-70% humidity. IMO for backyard flock purposes it's when you get to 75-80% that you start getting a bit iffy, and I'd say above 85-90% humidity is really courting trouble.

    HYGROMETERS ARE NOT USUALLY ACCURATE right out of the package; you need to use something like the salt method (see 'incubating and brooding eggs' section of BYC forum for instructions) to figure out how wrong yours is so you know how much to add or subtract to its reading. I would not suggest believing a hygrometer reading otherwise [​IMG]

    Cracking the doors is probably not enough ventilation, and is not a good location for it in wintertime. See my ventilation page (link in .sig below -- sorry to keep doing that, but the whole reason I did those pages was so I don't have to type all this stuff over and over and over [​IMG]) for details as to construction, location, size, and management of vents.

    Good luck, have fun,


    From @aart

    Hygrometer is easily tested:
    Hygrometers can be tested by putting 1/2 cup salt and 1/4 cup water in a dish or jar and mixing it to a slurry.
    Put the salt slurry jar and the hygrometer next to each other in a large sealed plastic bag.
    After 8-12 hours the hygrometer should read 75%... note any differences and you're set.

    From me:

    The hygrometer was 5 Percent below 75% for outside and 4 percent below 75% for inside. I marked the weather station with a sharpie.

    Here is a recent link to which hygrometer people use!
    Last edited: Dec 19, 2016
  2. centrarchid

    centrarchid Chicken Obsessed

    Sep 19, 2009
    Holts Summit, Missouri
    Looks like you have a heated coop where heat source sufficient to raise temperature enough that relative humidity drops even though actual moisture content increasing a little.
  3. Mrs. K

    Mrs. K Chicken Obsessed

    Nov 12, 2009
    western South Dakota
    I wonder Centrachid, I think she/he must have good ventilation above the chickens, pulling that humidity out. My own coop is perfectly dry this morning. No signs of frost or dampness on walls or ceiling. My pop door is open, and we hit -18 (at 6:00 am when I checked it, -6 now.

    Mrs K
  4. centrarchid

    centrarchid Chicken Obsessed

    Sep 19, 2009
    Holts Summit, Missouri

    Ventilation clearly operating. Balance under her current conditions good with respect to air exchange and heat production most likely coming from chickens themselves.
  5. mobius

    mobius Chillin' With My Peeps

    Heat is mostly from chickens themselves (~10 watts per chicken?) in an admittedly smallish coop. The only other heat source would be the 250 watt stock tank de-icer in the bottom of a bucket plugged in that cycles to keep water from freezing. No lights, no additional heat.

    When the chickens are out of the coop for 2-3 hours, and the pop door open, the temperature inside equalizes with outside temp. Even with the stock tank de-icer still inside.

    I am feeling strongly and rather excitedly that this may be best way to test ventilation since all of our coops and weather conditions are all so different. Hoping, anyway!


    Outside: 0F RH 78%
    Coop: 10F RH 70%

    Pop Door opened, chickens came tumbling out. Now in run on roosts!

    Thank you for your kind comments.
  6. Adalida

    Adalida Chillin' With My Peeps

    Nov 21, 2015
    Just curious if you mind sharing your location? I'm in Eureka (northwest Montana) and wondered where you call "deep northwest montana".
    Last edited: Dec 17, 2016
  7. centrarchid

    centrarchid Chicken Obsessed

    Sep 19, 2009
    Holts Summit, Missouri
    You might be able to calculate heat production by chickens by taking into account how much they are eating. The colder it gets they more heat they produce.
  8. mobius

    mobius Chillin' With My Peeps

    Love Eureka![​IMG]

    I am halfway between Kalispell and Bigfork!

    (Not in the Yaak, lol).
    Last edited: Dec 17, 2016
  9. Adalida

    Adalida Chillin' With My Peeps

    Nov 21, 2015

    Haha first thing I thought of was the Yaak...beautiful country out there but I don't think I'm self sufficient enough to live way out there at this time of year!
  10. Beekissed

    Beekissed Flock Master

    Watching this thread and your experiment with great interest! [​IMG]

    I don't have a humidity gauge in mine but do keep a large old Coke thermometer mounted at roost level to see how warm it is there at night....always pleased to note on the coldest nights it's usually anywhere from 8-10* warmer at roost height. And that's in a hoop coop, so no nice thick wooden walls on all sides...the birds are roosting right underneath cold wire and a tarp.

    Will be eager to see how your humidity levels correspond with comb changes, if any.

BackYard Chickens is proudly sponsored by