As with fields, building a coop involves efficiency considerations.
For 1 poultry farmer, the maximum coop size is 14×22, which will raise 45 chickens (Base Game).
At current production values 1 poultry farmer will produce more meat and eggs than they can carry to the barns at maximum flock size. Periodic reduction of the flock size will yield meat and eggs.
If one uses the More Productive Animals Mod, a coop of 14x22 will house 67 chickens but they will produce more eggs and meat and require more oats and water than one farmer can carry. Periodic reduction of the flock size will yield meat and eggs. A smaller size is recommended.
Once an area is assigned as coop, the land will became barren and has dark-mud-like color on the earth. This is a permanent change to the appearance of this area.