How does roof type affect humidity in the coop?

[Finnie]

One of the most hilarious examples was a version of the Purina coop built by non other than the experts on Good Old House. They did an excellent job of building what may have been one of the worst coop designs ever concocted.

Lol! I watched that episode, and hated their coop!

 

[gtaus]

Lol! I watched that episode, and hated their coop!

I saw that video, too, and decided on other options. For those who are wondering what that video was all about....

 

[gtaus]

Well, it is really tall.
You've got 8' walls, correct?
Many gambrels have short walls.
If you give me all the dimensions I can calculate the volume in cadd....
...or here's a visual.
View attachment 1986014

OK, took me awhile, but I got the dimensions. The walls are 6 feet tall, not 8 feet. The coop is ~6X12 feet, give a few inches. Here is a snapshot of the online gambrel rafter calculator I used:

What I would like to compare is the volume of that gambrel roof compared to a standard gable roof with a 4/12 pitch, so it would be 12 inches tall at the peak. If I just visualize a gable roof inside this gambrel roof, peaking at 12 inches, it would appear that the gambrel roof is ~3X or more volume. But if you can run the figures through your CADD, that would be great.

Again, I am thinking I have better humidity control because the gambrel roof design is just so much bigger than a standard gable roof. The hot, humid air is dissipated in the larger volume of the gambrel roof. My small vents at the front and back towards the peak seem to be adequate.

 

[gtaus]

Another source of heat is solar gain from the dark shingle roof and dark red paint. Both of those are radiating substantial amounts of heat into the structure. But that would only show up during daylight hours.....and to some extent, even on an overcast day.

Have you ever compared the temp / humidity difference during daylight hours and again several hours after dark?

Well, the roof is partially covered with snow, but the red building would be soaking up the heat during the day. That is when I have been observing the +5F difference in heat in the coop and outside and the humidity in the coop has been about 8% less inside the coop.

I did compare the temp and humidity after midnight tonight, and inside and outside the coop were the same. So I guess you nailed that one.

 

[gtaus]

The most efficient roof for air exchange is a single slant. inlets along bottom eave and outlets at top eave. Minimum 3/12 pitch is required. 4/12 or 6/12 pitch is excellent. 9/12 pich and the air is moving fast, creating a barrier-jet stream if you will so not mixing and moving out as much moisture. Low pitch makes the inlet mix well with coop air prior to venting out top end.

The ease of build and low cost of a single slant make them more attractive too.

I had considered the slant roof because of ease of build. I had not considered the benefits of air exchange with a slant roof. Good points.

 

[gtaus]

Much lower pitch than I had imagined. Quick and dirty cross section area.
View attachment 1987045

Thanks @aart, the numbers seem to confirm my suspicion that the gambrel roof had more than 3X the volume of the gable roof I was considering. I had not considered the 12/12 pitch as some have mentioned.

 

[gtaus]

Thinks the height of your coop is helping, have you ever put the hygrometer way up high inside the coop?

I put my remote temp/humidity sensor at the same height as my chicken roost - so about 5 feet off the floor of the coop.