There's always a lot of talk about temperatures and wether or not to heat coops. I always hear people say it's not necessary and it's a fire hazard. From my experience and from my lengthy research it seems full size chickens are more cold tolerant and there are certain breeds that deal better with it than others. My rhode islands and barred rock just go about their business and act normal when it's in the single digits. My wyandottes will do ok but they chose to stay in the coop most of the day and not venture out much.. But they are only 8 months old right now. My silkies don't do well in single digit weather. They stand with their heads drawn in and one leg up and they don't move around much. Sometimes they're even shivering. It's -18 here today (honestly I would love to move but my husband won't). So my silkies are in the garage where it's 35. But some people might not have the option to do that. I DO agree that in a lot of the states that don't get as cold as it does here it's probably not necessary to heat a coop. However, I think it depends on what breeds u have and where u live. It can stay below zero here for days at a time. I purchased something called a "Sweeter Heater". You can find a website online for them. They are fire safe and made for coops and dog kennels. There is also another company that makes a similar product and I've heard they are cheaper but I don't recall the name.
To each their own of course. Not everyone will agree with me. Just sharing my thoughts and experiences. Happy Valentines Day everyone!