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

[lazy gardener]

An other thought re: RH and temp. I'm sure that there is variation in RH AS IT RELATES to temp. In other words, I'm guessing that a fixed RH is more detrimental at a low temp than it is at a higher temp. And as Bee says, RH is likely to be an extremely variable number, based on temperature (more evaporation as the coop warms up and those frozen surfaces start to gather condensation which then evaporates or drips) The moisture laden air around a chicken's head in confined quarters is going to have much higher humidity than it will in a larger space.

 

[aart]

An other thought re: RH and temp. I'm sure that there is variation in RH AS IT RELATES to temp. In other words, I'm guessing that a fixed RH is more detrimental at a low temp than it is at a higher temp. And as Bee says, RH is likely to be an extremely variable number, based on temperature (more evaporation as the coop warms up and those frozen surfaces start to gather condensation which then evaporates or drips) The moisture laden air around a chicken's head in confined quarters is going to have much higher humidity than it will in a larger space.

I have seen humidity rise greatly along with temp, the worst frostbite I've seen here happened at about 28-30 degrees, can't remember exactly what the humidity was tho.

 

[centrarchid]

@lazy gardener

Condensation on head is not what causes the frost bite. The condensation is all over the body of the effected bird. The wetting of the entire pelage degrades the birds ability to thermoregulate making so even intermediate temperatures, as noted by aart, that are otherwise subfreezing can result in frost bite. The thermally / cold stressed bird shunts blood away from peripheral tissues (comb and wattles) making so they can cool down to point where ice crystals form in the tissues. I have dealt with two settings where frostbit occurs. That where poor ventilation is at play is the one I have dealt with the least because it is the easiest to defend against. The more common for me and also more frequent than given credit to is that caused by generally much cooler temperatures complicated by wind irrespective of RH. That plays out for me when birds active during the day but also involves the drafts many talk about with birds confined to coops.

 

[Mrs. K]

I think a huge amount of the variance in humidity also depends on your climate as a base line, then day to day changes in the weather.

I am naturally very dry here most winter days. However, a deep snow + warm temperature day times, then darn cold nights are very common. At this time the manure will thaw, the snow melts and air temperatures rise which will then hold more moisture, daylight ends, temperatures drop, and a good case of frostbite can be had.

I do not have an instrument to test for humidity, but often times your nose can tell you. If you are smelling the coop, then more than likely temperatures are warm and it is pretty high humidity. Removal of manure and addition of dry bedding will bring it down. This last year, by adding scratch on top of the bedding, the scratching action of the chickens break up manure pods, and stir the bedding, with good ventilation this has kept the bedding much dryer.

I enjoy this documentation and hope you keep recording it.

Mrs.K

 

[Mrs. K]

Quote: I am not sure of this, and again, I think it is different climate. We were so dry here, that even though the ground is frozen, the top layer is so dry that with a little traffic on it, it breaks into loose sand. Friday, we got 8 inches of snow and cold, followed by bitter cold, as in -38. But the outdoor humidity was quite low, the snow was frozen and had no effect. No frostbite on my birds.

Today, the wind is howling, and temperature in near 40 (but does not feel that warm blowing over the snow) humidity is rising. A drop in temperature tonight, with the darkness, could be a problem.

Mrs K

 

[Beekissed]

I rarely see frostbite signs in single digit or subzero weather. It's always in 20-30s after rain or snow...like right now. Single digits and windchills of below zero last week yielded nothing significant on the rooster's comb or wattles. The other night we had temps of 65 and torrential rain for two nights in a row, followed by a sharp drop in temps the following day into the low 30s, with low 20s that night....and the next morning I noted a few darkened tips on the rooster.

I had shut down one of my lower vents when we had the subzero temps and high winds and that was fine for then, but when extreme moisture followed by regular winter temps followed, that slight adjustment of the ventilation resulted in a frosting of the rooster.

Today I opened that lower ventilation and additional ventilation next to the roosts and will monitor results. Usually these small adjustments rectify the problem.

 

[Egghead_Jr]

And nothing wrong with the window or @Beekissed 's comb solution! I just wanted a little more precision myself (and don't have Beekissed's rooster ( or any rooster

)). I wanted more precision because it is my first winter with chickens, and the weather outside is frightful! I mean I had no idea what -12F would bring in terms of humidity! Now I do know. Better.

Incidentally, and I welcome response to THIS finding, I just googled ideal humidity winter chickens on the internet. I looked and looked, similar to what @lazy gardener did, only for small flocks. I DID NOT FIND anything! definitive except for people quoting much lower levels of humidity than I have found, or quoting humidity levels used by large scale chicken producers. I did not find a test case on backyard flocks. Not one!

I did find a lot of folks and some chicken bloggers randomly stating what is best, or talking about humidity tips while avoiding discussing specific levels of humidity.

Guys, we can't just "make it up" or take everything we read on the internet to be the case. If it were, my last few nights would have been over the top for humidity.Turns out @patandchickens advice at beginning of this thread may be the best we have.

As Beekissed mentions, and to supply another datapoint, these humidity levels I am reporting (try to keep it under 75%, 85% would be absolute max) include observing chicken's combs. All chicken combs to date are just fine!

100% RH is the dew point and when temp is under 32 F/ 0 C it's called the frost point. Warm air holds more moisture than cold air hence humidity percentage is relative to temperature. It's a scale measuring percentage of total saturation. If the same amount of water is in the air at 0 F that there is at 10 F then the humidity is lower at the warmer temperature. Where 85% humidity would pay off as a max for coop temp is if measured at dusk as that could turn to 100% overnight as temperatures drop quickly.

 

[centrarchid]

100% RH is the dew point and when temp is under 32 F/ 0 C it's called the frost point. Warm air holds more moisture than cold air hence humidity percentage is relative to temperature. It's a scale measuring percentage of total saturation. If the same amount of water is in the air at 0 F that there is at 10 F then the humidity is lower at the warmer temperature. Where 85% humidity would pay off as a max for coop temp is if measured at dusk as that could turn to 100% overnight as temperatures drop quickly. 

When you have continued replacement of colder outside air that is heated as comes into coop, presumably by chickens, then the RH drops. To make system work you need heat input that is properly sized relative to the air flow.


Building size also important. Party I have worked with down the road had frost bite issues because building too large. You will have to think about that for a bit to see how it works.

 

[Egghead_Jr]

Was stating some things about RH and what dew/frost point is. As I was reading this thread there seemed some confusion on it. A sign of bad ventilation in a coop would be if the humidity was the same as outside humidity when the temp is higher in the coop. This would prove the moisture produced from chickens is not being vented out of coop. As the warmer coop air can hold more moisture so RH must be lower or your chickens are adding moisture- coop is inadequate in venting it out. The OP has good ventilation and it's proven by the RH always being lower in the warmer coop than outside. Their are scales to show RH at different temp (same moisture content by volume) and one could ensure no added moisture is in coop via a chart and your measurements.

 

[centrarchid]

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