A curtain wall is an outer covering of a building in which the outer walls are non-structural, utilized only to keep the weather out and the occupants in. Since the curtain wall is non-structural, it can be made of lightweight materials, such as glass, thereby potentially reducing construction costs. An additional advantage of glass is that natural light can penetrate deeper within the building. The curtain wall façade does not carry any structural load from the building other than its own dead load weight. The wall transfers lateral wind loads that are incident upon it to the main building structure through connections at floors or columns of the building. A curtain wall is designed to resist air and water infiltration, absorb sway induced by wind and seismic forces acting on the building, withstand wind loads, and support its own weight.
Curtain walls may be designed as “systems” integrating frame, wall panel, and weatherproofing materials. Steel frames have largely given way to aluminum extrusions, typically infilled with glass, which provides an architecturally pleasing look and benefits such as daylighting. However, the effects of light on visual comfort as well as solar heat gain in a building are more difficult to control when using large amounts of glass infill. Other common infills include stone veneer, metal panels, louvres, and operable windows or vents.
Curtain wall systems differ from storefront systems in being designed to span multiple floors, taking into consideration building sway and movement in addition to design requirements such as thermal expansion and contraction; seismic requirements, water diversion; and thermal efficiency for cost-effective heating, cooling, and interior lighting.
