Ummm, not sure a winterized coop will keep them laying. Laying is determined by daylight length and when it drops under 14 hours laying tapers off. If you want them to lay through the winter, they need 2 things. First, a continuous source of not too cold water. Without constant water, they cannot digest their food. Without sufficient nutrition, laying will be poor.
Secondly, they must have light. A 60 watt bulb not higher than 10’ above where they spend the most time, on a timer for 16 hrs of light. Ideal is adding hours before dawn and after dusk, but I found getting them in the coop was hard when the light was on at night. If the light is on early in the morning, it is crucial they have food and water during that time. Often chores are not done until much later.
Just a couple facts to think about...
RE: Lot of snow, firewood cutting and first winter deeds