Can the treadmill be put on the balcony?
Why not? A balcony with a roof will do. If you are afraid of the sun and rain, you can push it out when you run and push it back when you don't run. I always do. I use the Lin Kang treadmill to fold easily. I often push it out for exercise and then fold it back after exercise. The air on the balcony is better than that in the room.