Craftsman-style homes are classified into four types: prairie, mission, four-square, and bungalow. The bungalow style is the well-known and beloved craftsman style. They are typically made of wood or stone and have broad roofs. The walls usually have two stories with an attic space above. There may be a porch or balcony at the front entrance, or not. The rooms tend to be spacious and open, with large windows for natural light. The ceilings are often high with exposed beams. Bungalows were originally built by builders who did not have a license in some states, so they are sometimes called "illegal" bungalows. Today, any homeowner can build a bungalow-style house as long as it meets certain requirements set by local building codes. An illegal bungalow does not have full plumbing facilities, for example; instead, it has toilets and sinks installed without sewage lines. It also might have only one door and no window glass. Mission and Prairie styles were popular around 1900. These houses have flat roofs covered with gravel or tile and look very different from modern bungalows. The walls are usually painted white, but other colors are available if you ask your builder about custom options. A mission-style house will usually have three doors, while a prairie-style house will have five or more.