Curtain walling is a term used to describe a building facade which does not carry any dead load from the building other than its own dead load. These loads are transferred 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, wind forces acting on the building, seismic forces, and its own dead load forces.
Curtain walls are typically designed with extruded aluminum members, although the first curtain walls were made of steel. The aluminum frame is typically infilled with glass, which provides an architecturally pleasing building, as well as benefits such as daylighting and environmental control. Other common infills include: stone veneer, metal panels, louvers, and operable windows or vents.
Curtain walls differ from storefront systems in that they are designed to span multiple floors, and take into consideration design requirements such as: thermal expansion and contraction, building sway and movement, water diversion, and thermal efficiency for cost-effective heating, cooling, and lighting in the building.
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There are different perceptions on rainscreen cladding, ranging from rainscreen panels or ad-hoc supporting frame for panels to integral systems with backing walls. Primarily a rainscreen system is a layered cladding system comprising of:
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A visible outer skin or rainscreen that forms the primary rain barrier. This layer sheds the majority of the water down its surface but does not prevent the passage of air into the air gap.
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An air cap that prevents water ingres into the building. This provides ventalation and depending on the design and dimensions of the rainscreen and air gap, maybe intended to provide pressurequalisation across the outer skin.
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A backing wall that forms an effective air barrier and frequently includes an insulating layer.Typically the supporting system to which the outer layer is fixed
A concise definition of rainscreen cladding is:
"A layered cladding system comprising typically of an outer skin which incorporates an air gap and provides the primary rain barrier, an air gap that prevents water ingres and an effectively impermeable backing wall"
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