Concrete and Brick
Poured concrete and stacked concrete blocks, as well as bricks, may be used in commercial building construction. A building's foundation is typically concrete, but may also be a combined foundation of concrete, steel and other materials. Basement foundations in commercial buildings may house utility areas, such as boilers and furnaces, or serve as an additional level for office space, retail space or other commercial applications. Commercial buildings may also have exterior concrete walls, which are typically made from stacked concrete masonry. Brick masonry also adds a unique aesthetic aspect to a building's facade, and may be used both for its sturdiness and visual appeal.
Steel and Metals
Steel girders provide a strong, stable framework around which to build the walls of commercial buildings. Steel is essential to skyscraper construction, as the lower girders are able to support the weight of the building materials used in the numerous upper floors. Reinforcing bar, also known as rebar, is also used in concrete structures to increase their strength and durability. Softer, lighter metals such as aluminum may fill in the spaces between steel girders or make up the ductwork that runs through the building's walls and ceilings. Conductive metals such as copper are a common component in the electrical wiring within a building's walls, as well as plumbing.
Lumber and Sheetrock
Wood frames may supplement stronger steel or concrete walls, or may be used for non-supporting interior walls. Smaller commercial buildings, such as one- or two-story offices and shops, may have both interior and exterior walls framed with wood. Wood wall frames are covered with Sheetrock (a brand of gypsum wallboard) and other drywall materials to complete the wall's structure and to provide support for electrical outlets and switches.
Each commercial building has its own unique energy needs but these structures typically use over half of their energy for heating and lighting. In order to reduce energy consumption, insulation is placed in the walls to minimize heat transfer between the interior of the building and the outside. Fiberglass is a material commonly used for insulation, but any thick and porous material may provide some protection from outside temperatures. For several decades during the 20th century, asbestos was also used in insulation for its flame-retardant properties. When it was later found to contain microscopic fibers that, if inhaled, cause lung cancer, asbestos was phased out of insulation materials.