A curtain wall system is an outer covering of a building in which the outer walls are nonstructural, but merely keep the weather out and the occupants in. When glass is used as the curtain wall, a great advantage is that natural light can penetrate deeper within the building. The curtain wall facade does not carry any dead load weight from the building other than its own dead load weight. A curtain wall is designed to resist air and water infiltration, sway induced by wind and seismic forces acting on the building, and its own dead load weight forces.