Walker stays outside all year, this is his house He can go in and out as he pleases all year..During summer the door is wide open These flaps are made of many layers of 6 mil poly,as you can see they need to be replaced every few years. When it starts cooling down in fall I add this easy to remove insulated panel (one screw secures it)with layers of vinyl flaps to keep the heat in and cold out.When winter really arrives I add another set of flaps. If we are supposed to get severe weather I close the door to keep him in This is how I have the door opening set up now, added some flaps and lowered the door height to the summer opening.This is secured by a screw in the center for easy removal.Here is a pic of the inside, You cant see it but there is 3x4ft Stanfield heat mat just inside the door to the right. It measures 7x7 ft inside so I can rake it and use a push broom to clean it and then use a shop vac with an extended hose to get whats left from outside without having to crawl in..