I am subject to -40º weather l live in Canada think North Pole. I have 65 trips around the sun and have been keeping chickens and birds for decades. Your best practice I find is to not be too concerned about winterizing your coop; Predator proofing "ABSOLUTELY". Your efforts should be spent in winterizing your birds and letting them acclimatize to their surroundings. This is done by feeding them whole corn if available or cracked corn. The extra protein is more then adequate to bring them through the "COLDEST" winter. Do keep an eye open for birds that maybe not be adapting well to the new menu and may be at the lower end of the pecking order they can sometimes run into problems and may need extra TLC. That being said in a perfect world the flock will flourish and do just fine . I do not add any extra heat or lighting. Egg production does slack off but I have more than enough eggs for the table all winter long (24 hens). Some people may disagree with my method but it has worked well for me and I am not about to change. I look at it in the same light as winterizing your car. You really do "NOT" have to winterize your car if you can keep it in a controlled environment at all times otherwise you are in for "MAJOR" problems.