Beyond confused, please help. Coop sizes
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If you don't plan to coop the birds in winter then a large run is far more important to behavior problems in a flock. Smaller coops work quite well if they are only used as a place to roost at night and let out of coop every morning. An example would be 6 layers in a 4x4 coop with external nesting box- coop access to box with lid access outside to collect eggs. Food and water not kept in coop and a large run. That works very well. If the coop is on stilts then the feed can stay dry under it.
Large coops are nice. I don't use them as I make coops portable. Walk in coop with area for nesting boxes and feed on hangers from ceiling, plenty of space for birds to scratch about inside. This certainly has a lot of appeal. 4sqft per bird is not enough if housed in coop when cold weather hits. It's large enough to keep nesting boxes, food and water in but then you still need to let birds out everyday as they've no run around room in coop.
The more I crowd them the more behavioral problems I have to deal with, the harder I have to work, and the les flexibility I have to deal with issues that come up.
Chickens don’t have a concept of coop space versus run space. All they care about is space, wherever it is; coop, run, coop and run combined, or the great outdoors. Don’t think of coop space in isolation, think of how much room they have and how you manage them to optimize that space.
A lot of this has nothing to do with the chickens, it has a lot more to do with your comfort and convenience. It has to do with your stress levels.
It's all about advertising for the coop builders. They don't care about standards, etc, just sales. Same reason every commercially made purple martin house will likely mention the thousands of mosquitos that purple martin eat. It has been proven time and time again that martins very rarely (if ever) eat mosquitos. Many people believe they do and see that and buy the house without any knowledge.
You don't need insulation in Pennsylvania. I'm in the North East Kingdom of Vermont without heat or insulation in the coop. Adequate ventilation to keep the coop dry and clean air without drafts on birds is all they need.