04/10/2018_In the unitized system, the wall is composed entirely of large framed units pre-assembled at the factory, complete with spandrel panels (if any) and sometimes also pre-glazed. The vertical edges of the units join to form mullion members, top and bottom members join to form horizontal rails, and the units may be one, two or sometimes three stories in height. It provides assembly under controlled shop conditions, where the work can be carefully inspected, and facilitates rapid enclosure of the building with a minimum of field labor and relatively few field joints.
Typical wall units are designed for sequential interlocking installation, and when openings have to be left in the wall to facilitate the handling of construction materials the units installed later to close these openings usually require special joint details and installation procedures.
Advantages over stick or window wall systems:
- System built under factory conditions leading in higher quality.
- High performance achievable for thermal, structural and water infiltration resistance.
- Fabrication of panels is done during the erection of the building frame and can be concurrent for faster installation.
- Can tolerate large building movements without the degradation of system performance.
- Logistics and staging can be done from each floor and multiple panels can be hoisted to floors for local installation and staging at the floor level.
- Access from the outside of the curtain wall is typically none or minimal.
- Opaque portions of the façade can be incorporated within a façade unit.
Disadvantages compared to other system types:
- Unitized systems have no discernible disadvantages to other system types when considered for use in a high rise tower.
- Although initial cost may appear higher the cost of unitized systems, it is offset by GC/CM fees, general conditions, and better schedule when compared to window wall or stick built systems.
Durability and Life expectancy:
- Unitized curtain walls can be expected to achieve 50-year life with proper maintenance.