Lastly, the temperature differential may cause the building elements to expand and contract, which, again, can result in relative movement between structural elements. Third, concrete structures typically encounter creep and shrinkage, and there may be foundation differential settlement or soil compression from high-gravity loads. Second, the structure sways and has torsional displacement due to movement from lateral wind or seismic loads. At first, it was not obvious to me why making this allowance was necessary, but our product development team creatively explained some of the reasons why this is an important must-have feature for curtain walls.įirst, the primary building will move up and down as it is loaded and unloaded by the live-load occupancy, similar to beam live-load deflections. One essential function of the curtain wall is to allow for relative movement between the curtain-wall system and the main building structure. They include, but are not limited to, exterior insulation finish systems (EIFS), glass-fiber-reinforced concrete (GFRC), bricks, metal panels and stone panels. There are many different types of cladding materials. The framing studs are typically spaced at 16″or 24″ on center. It is typically constructed with cold-formed steel studs ranging from 31/2″ to 8″ deep, in 33 mil (20 ga.) to 97 mil (12 ga.) steel thicknesses. The back-up framing is the structural element of the curtain-wall system. The cladding curtain-wall system is the type in which Simpson Strong-Tie products can be used. The cladding curtain wall is a system with back-up framing that is covered in some type of cladding material. Glass curtain-wall systems are usually designed using aluminum-framed walls with in-fills of glass. Glass and cladding curtain walls make up two basic types of curtain-wall systems. Additionally, curtain walls receive wind and seismic loads and transfer these forces to the primary building structure.
Curtain walls are not part of the primary structural framing for the building, but they typically rely on the primary structural framing for support.
To put it in structural terms, a curtain-wall system consists of non-load-bearing exterior walls that must still carry their own weight. When I first learned about the use of cold-formed steel curtain walls, I laughed and thought: “Gosh, how useful this would be for someone growing up with 5 siblings in one bedroom!” I have always enjoyed the sense of humor that our engineers use to help explain technical topics.Ĭurtain walls can be described as exterior building walls with the primary purpose of protecting the interior building against the exterior weather and natural phenomena such as sun exposure, temperature changes, earthquakes, rain and wind. Our lead engineer for developing our line of connectors for curtain-wall construction explains the purpose of the curtain wall with the illustrations below.įirst, curtain walls are not what you put up if you shared a room with your brother and sister when you were growing up. In August 2012, Simpson Strong-Tie launched a comprehensive, innovative solution for curtain-wall framing.