We have a 5' x 5' coop that was built from an old coop or dog house that the previous owner left behind. It was basically just an empty wooden box with one door and no roof. It was totally out of square and needed a ton of revisions and is still out of square but we made it work. Nothing is insulated or sealed. The walls are old 3/4" particle board and the floor is 2" x 6" pine. We added a nesting box made from 1/2" plywood. The particle board walls get wet every time it rains. Should the walls be sealed and what is safe? The floor has small spaces between each board. Should we put a solid piece of wood over the floor to keep out insects and cold drafts? The roof we added is just corrugated plastic. I installed 2 vents at the top back wall and one at the top of the front wall. They face E and W. There are 2 doors on the coop, one on the back facing west and one on the south side. I keep the doors open during the day for further ventilation. They are of course secured each night and heads are counted. This will be the first winter for our six full sized hens and three 8 week old pullets. We've had 2 mornings in the past week in which their water has been frozen. We had planned to insulate the coop but haven't had the money or time till now. We are kind of at a loss as to how to go about adding insulation without having to nearly re-build the coop. We are new to chickens and even though I have read a lot of articles and searched for information on BYC we still feel out of our element at times. I need suggestions for insulation and advice on how much ventilation is needed. We figure we should insulate the roof at the very least since it's only corrugated plastic attached to a wooden frame. Also is it a good or bad idea to leave both doors open during the day when the temperatures are below freezing? As you can see in the pictures I also propped the roof open during the warm weather.