The framework of the curtain walls is mainly made of extruded aluminum frames, although the earliest curtain walls were made of steel
A curtain wall is designed to withstand:
- Air infiltration and exfiltration (air can pass through the curtain wall through mullion and transom trims, as well as any defects in the caulk. In the United States, this is the American Architectural Manufacturers Association (AAMA) which governs the acceptable levels of air infiltration in curtain walls.) And water (rain, seepage water, condensation water, snow, ice, etc.);
- Wind force or even hurricane-force: wind loads vary considerably from region to region, with the heaviest loads occurring near the coast in areas prone to tropical cyclones. (By country or climatic zone, there are Building Codes determining the mandatory resistance standards for the realization of specific projects);
- Thermal expansion and contraction;
- To earthquakes;
- Wind projectiles and other aerial falls;
- explosions: the curtain wall must resist the blast of explosions, both accidental and of a terrorist nature;
- to construction movements such as concrete creep. It must also withstand point loads such as cleaning pods, for example.
In order to guarantee foolproof impermeability, curtain walls are fitted with waterproofing gaskets. There are several kinds:
- dry: linings in neoprene, EPDM, Santoprene, silicone, PVC or polyvinyl chloride, Hypalon, etc.
- in the ribbon: preformed, etc.
- paste: silicone, polyurethane, polysulfide, acrylic, latex, etc.
Different models of curtain walls:
- Self-supporting aluminum frame mesh type curtain walls (also called a ” stick ” system) assembled and delivered to the job site in spare parts. They are made up of long vertical profiles called “mullions” and horizontals called “crossbars”. This system generally has the advantage of being the most economical on the market, to the detriment of the installation time required and at the cost of a heavier architecture.
- Self-supporting aluminum frame mesh type curtain walls factory assembled and delivered to the jobsite as a complete unit (also called “sealed unit” or “preglazed curtain walls” or “unitized or preglazed”). Quick to install, they also have the advantage of allowing quality control since they are manufactured in the factory under controlled conditions. However, their handling of transporting pre-assembled parts requires heavy equipment, such as cranes, etc.
- Hybrid curtain walls , which are located halfway between a “ stick ” system and a “ unitized ” system. They use a conventional curtain wall structure on which a frame with factory-assembled glazing is attached. Always quick and easy to install, no aluminum profile is visible from the outside. In addition, in the event of a breakage, the work of replacing a glass is carried out in a few minutes, unlike the conventional siliconized system, done on site, which requires a lot of work.
In addition to these three major curtain wall systems, there are also greenhouses, skylights and sunrooms.