Not sure how I missed this thread. My 24' X 25' shop has 12' walls. I have two 10' X 10' roll up doors. They have a chain like a chain hoist. No spring assist. Pretty easy to roll up. Very heavy doors, so I chose chain hoist instead of spring assisted pull up. As I get older, I would worry about my back.
Here's an early video.
LINK HEREI'm pleased with the doors and ease of use. There is a flap type seal along the top edge because when the door is down the gap between the large drum and the top of the door frame is large. That gap becomes smaller once the door is up because the drum is wrapped with the door.
