Many on this site use the 4sq ft in the hen house and 10sq ft in the run. So 50"x85" is about 29.5 sq ft or 7.4 chickens. While the 12'x50' is 600 sq ft or about 60 chickens. You'll need to predator proof everything to make it safe for chickens. Have fun. Remember each persons set up is...
Consider having part of your run covered so the hens can come outside in bad weather. Our run is predator proof so we allow our hens 24/7 access to it and keep the food and water there, but we live in S. CA. very different winter weather then you'll be facing. Good luck and enjoy.
I feel your pain... 3 years ago our daughter brought 8 chicks home from school in a large cardboard box. Didn't realize what it was going to take or that we had a vacation scheduled. They ended up living in our family room on a sheet of plywood (on a tarp) in a simple hoop coop for about a...
I might try filling up past the wire floor with shaving to pad the feet. You might have to put something in side the cadge to keep the shaving from falling out.
This was our chicks first outside home. You could tuck it something like it in a corner. You may not be able to see that there is 1/4" hardware cloth on the windows. We also added plenty of bolts to hold it together. Yes, we all ready had the playhouse and the kids were happy to turn it over...
Sounds like it may be perfect for you.... I guess I was in-visioning it in the main part of your yard. I've found staying flexible with our girls helpful. Have fun.
Many on this site suggest 4 sq ft of house space for full size chickens. This design only provides 8sq ft so would house about 2 hens. I love this design for it's simplicity, and as someone new to chickens, plans are so helpful! Here is anther set of plans and a post on space.
Purina Hen...