Scaffolders provide temporary structures that give workers safe access to buildings and other work areas at height. They typically plan, erect, adapt and dismantle scaffolding for projects such as building work, repairs, painting, roofing, refurbishment and maintenance. Some businesses supply scaffold components for hire as well as providing the labour to install and remove them. Services may include traditional tube-and-fitting scaffolds, modular system scaffolds, access towers, stairways, loading platforms, edge protection and temporary roofs. The arrangement is selected to suit the building, site conditions, work being carried out and access required. For more complex projects, scaffolders may prepare designs and supporting calculations, coordinate with other contractors, and carry out inspections during use. Scaffolding must be erected and altered by trained workers, and inspected by a competent person at the required intervals and after events that could affect its safety.