A curtain wall is an outer covering of a building in which the outer walls are nonstructural but are attached to the building structure and used to keep out the weather.
Because thecurtain wall is nonstructural it can be made of a lightweight material (e.g., aluminum-framed walls containing infills of glass, metal panels, or thin stone)
, reducing construction costs. The use of glass as the curtain wall has the advantage of allowing natural light to penetrate deeper within the building.