The surfaces to which floorcovering materials are applied are known as substrates or subfloors. They can be made of wood, concrete, plywood, stone, or metal, among other materials. The substrate must also be devoid of fissures that are large enough to allow light to pass through the flooring material. These fissures may come from previous repairs to the floor or may be present due to natural causes such as an earthquake. If the substrate is not stable, you may want to consider using a foundation underlayment first to provide stability. The substrate should be cleaned thoroughly before applying a flooring product. This includes removing any stains or dirt and wiping down any oily surfaces. Any loose items such as screws or nails should be removed from the site before work begins. There are two main types of substrates: horizontal and vertical. Horizontal substrates are those found in homes and commercial buildings. They can be made of wood, concrete, or steel. Wood substrates are available in several varieties including oak, maple, hickory, sycamore, and pine. Concrete substrates are usually color-graded by manufacturers; they often include black, grey, or white as options for the user to choose from. Steel substrates are used primarily in industrial settings and are available in a wide variety of colors including black, blue, red, yellow, and silver. Vertical substrates are found in warehouses and other commercial settings.