We recommend sun rooms be 8’x10′ on the small end or 18’x18′ at the large end. An 8’x10′ room would be 80 square feet and this is the size of a small bedroom. An 18’x18′ sun room 324 square feet. As a reference, my first studio apartment was only 400 square feet.
An 18’x18′ sunroom would be used mainly for someone that plans to do a lot of entertaining. In college my friend’s home had had a 14′ x 14′ sunroom with a hot tub, couches and a large screen TV.