Roof forms with gable ends They feature two sloping sides that meet at a ridge to form end walls with a triangular projection at the top called a gable. The gable may be flat or scooped out. Gables were used primarily for decoration but they also provided extra living space inside the house. The roof was made of wood shingles or tiles, and the exterior might have been painted white or stained dark colors such as red or black. The interior walls might have had paneling or wainscoting (a type of wall treatment derived from ancient Roman construction techniques). Carpets or other floor coverings would have added to the comfort of those living inside the home. People began building homes with gables because they were easy to construct and they gave the houses a decorative touch. Early builders didn't always build their houses completely solid up to the ceiling height. Rather, they left some space under the roof which allowed air to flow through the house and made it more comfortable to live in. As time went on, people started filling their gables with furniture so they could use the space for storage or even as bedrooms. By the 19th century, roofs with gables were common throughout much of the United States.