Cladding businesses supply, install, repair and maintain materials fixed to the outside of buildings. Cladding forms an external finish and can help protect walls from rain, wind and other weather, while contributing to a building's appearance and, depending on the system, its thermal or acoustic performance. Common materials include timber, brick slips, metal, stone, render, fibre cement and composite panels. Services may include assessing existing walls, preparing surfaces or support frameworks, fitting panels and trims, replacing damaged sections, sealing joints and cleaning or treating surfaces. Some contractors work on new homes and extensions, while others handle larger residential, commercial or industrial buildings. Work can involve access equipment and coordination with other building trades. The materials and method used depend on the building, its structure, exposure and intended use.