There are two main types of sunrooms—3-season and 4-season. Both are suitable for Maine homeowners looking to add a sunroom to their homes, but they differ in how long you’re able to use your sunroom (comfortably) throughout the year. A 3-season sunroom offers a relaxing space during the spring, summer, and fall. Being as they are not heated, they do not inherently feel comfortable during the winters. 4-season sunrooms, also known as year-round sunrooms or all-season sunrooms, feature insulated walls, floors, and windows, for year-round comfort.