Are there any similar plans anyone knows of that will accommodate 15-20 chickens? This is our first coop btw so if anyone sees anything we’re not consider...we really appreciate everyone’s feedback an opinion!
A common estimate is 4 square feet of space per chicken inside the coop (sheltered area), and 10 square feet per chicken in the run (fenced area outdoors).
The largest of those tractor coops is 8 x 10 feet at the base.
If you treat the base area as the run, that would give 10 square feet each for 8 chickens.
For 8 chickens, the coop (sheltered area) should be 32 square feet.
I cannot find any dimensions for that upper area, so I can't tell if it's big enough or not.
So I'd figure the largest of those tractors as holding 8 chickens or less, not 15-20.
Using your shed sounds like a MUCH better option.