Cladding is the exterior covering of the structural components of a building that are made up of steel sections.
This covering may be made up of reinforced concrete, wood, aluminium or any other architectural and light weight material.
Sections made by combining two or more hot rolled sections, joined together at intervals are called built-up sections.
This joining is done with the help of direct welding, stay plates or lacing.
Examples are four angles section, double angles section and double channel section.
However, double angle section is sometimes excluded from built-up member and is included in hot rolled section. This is because of difference of its behavior with respect to other built up sections.