A roof isn’t required over a hot tub, but it has some nice perks. If you’re in an area that gets a lot of snow, it’ll minimize the need to shovel off the cover. In the summer, it provides shade. It can also create a feeling of privacy. Protecting your hot tub from the elements will extend the life of your hot tub cover. However, a roof might block your view of the stars if you're a night soaker.