Curtain walls can be defined as non-structural aluminum-framed walls, containing infills of glass, thin stone, or metal panels that are connected back to the building structure. There are two main categories of curtain walls: unitized curtain walls and stick-built systems. So how do you know which one is right for your building?
Unitized curtain systems are composed of large glass units that are created and glazed within a factory and then sent to the construction site. Once on site, the units can then be hoisted onto anchors connected to the building. High quality, due to tight tolerances of fabrication in a climate-controlled environment, is only one hallmark of this type of system. Since there is no on-site glazing, another major benefit of using a unitized system is the speed of installation. The system can be installed in a third of the time of a stick-built system. This system is well suited for cases where there is a large volume of prefabricated unitized panels required, where there are higher field labor costs (thereby shifting the labor to a more cost-effective factory work force), where higher performance is needed (for wind loads, air/moisture protection, seismic/blast performance), for taller structures, and more regular conditions for panel optimization.
If your project doesn’t suit most of the criteria for a unitized system, your other option is to use a stick-built system. The vast majority of low to mid-rise curtain walls are installed in this way. Long pieces of aluminum (hence the name stick) are inserted between floors vertically and horizontally between vertical members to support and transfer the load of the glass back to structure. Most of the erection and glazing for a stick-built system is done on site. One of the benefits of stick-built systems is its economic friendliness for facades that have lower required volumes and many complicated conditions. The lead times for these types of systems are often much shorter for fabricated materials to be delivered to the site and allow for less up front staging. This is shorter in comparison to a unitized system, where six months to a year can be required for this process. However, the trade-off is that the installation takes longer to complete on site. You also need a significant amount of space for installation and storage of material on the site, which can be difficult in many high-traffic cities with tight job sites.