We have a basement bulkhead door that we never use. It leaks air. What's the easiest way to go about insulating this? I was thinking about just getting foam board, and putting the foam board over the door in the basement. (I should point out that the bulkhead stairs go to a full door that's in the basement.) So it would be like putting foam board over a wall, except in this case there will be a door behind the foam board. I suppose I'd have to cut a hole for the doorknob. I'm not very handy, so I'd like something easy. Any advice?