What Are Portable Buildings? Portable buildings, also sometimes called sheds, are freestanding structures, often made of wood. You'll often find the buildings in backyards. Some of the buildings are designed to match the style of the main house, imitating the color and features of the primary residence. While some sheds or portable buildings can be on display or in full view of anyone who might pass by the yard, others are meant to blend into their surroundings. They might have a simpler style or be positioned behind the main house so that they aren't easily spotted from the street or front yard.