Building materials are the materials which are generally used for construction purpose in Combine. Lots of natural substances, such as clay, sand, wood and rocks, even twigs and leaves are used to construct buildings. Apart from natural materials, many man-made goods are also in use these days in Combine, which are more or less synthetic. Building style and structures would depend on the type of material used for construction in Combine. The deciding factor is usually connected with the quality of the material being used. Rock or stone structures have existed for as long as history can recall. It is the longest-lasting building material available, and is usually readily available compared to other building materials.