10F isn't that bad. We don't get as cold here but my chickens have spent nights at 12F pressed up against open windows in the coop without issue. Usually when I see folks talking about confining chickens through the winter, they're talking about arctic climates, where you're looking at extended periods at -20, -30F or more.At the coldest, about 10 degrees fahrenheit? We've only been in the Catskills one winter, but it's definitely not as bad as where I'm originally from (Wisconsin). Lots of snow though. You know, there must be ventilation - the previous owners kept chickens in this thing successfully. I thought ventilation meant windows but I might have missed openings at the eaves/higher up in the coop. Will check and add along with windows if none is there. Thank you!
Optimally you will want to have a covered or climate proofed run so they can get outside even in winter weather, just to reduce any chance of behavioral issues popping up from confinement, even if you plan on culling down the flock each winter, which some folks in colder climate areas do practice.