Storefront Water Management: Since storefront systems are designed for single-story applications of up to 12 feet tall, the integral water management of these systems is not designed to handle any more water than that. Typically storefront systems are designed to allow excess water to seep past gaskets consistent with their lower performance class and grade. This water is then collected internally by horizontal frame members and channeled into the adjacent framing members. From there, this water is intended to drain down to the sill flashing members and exit out through weep holes. Obviously the effectiveness of this type of water management system is limited by the size and frequency of the channels and the weepage available. Storefront system designs that contain a greater number of members and joints obviously also have a greater number of places where water can infiltrate through those joints. Further, if the storefront system is installed in a situation where the amount of water infiltrating the frame exceeds the capacity to drain it away, then the water can overflow into the building and cause damage there. Protecting a storefront system with a canopy or other external protection can help in this regard.

Storefront Fabrication: Storefront systems are generally fabricated locally by a glazing sub-contractor from standardized parts provided by a manufacturer. Typically, the same local fabricator is also the installer of the system and will field install the glass or infill materials. While this allows for considerable flexibility and responsiveness, it also reduces uniformity of fabrication and inherently creates more variation between installers with regard to performance. Due to this field assemblage of storefront, the warranty for the fabrication and installation is provided by the local sub-contractor and not by the manufacturer.

Storefront Strengths: Storefront systems are generally viewed as convenient for contractors with multiple local suppliers/installers able to produce a system within a relatively short lead time. The field installation with a dry gasket system means that fabrication is readily available and subsequent re-glazing or replacement is easy. In terms of cost, these systems are typically the least expensive when compared to curtain walls or pre-glazed window systems.

Storefront Limitations: Since these systems are intended for single-floor installations, they are not designed with an internal structural capacity beyond that. That means that there are very limited provisions for a supplemental structure within the frames and their Performance Grade ratings are limited accordingly. Thermally, they are not typically offered with all of the high performance characteristics that are desired, and performance becomes very dependent on the proper field installation of the system. From a design standpoint, they also offer limited customization of mullions and accessories, limited anchorage options, and limited opening configurations. Finally, the full performance of the system is typically covered by a warranty that comes from the local supplier/installer and not a national manufacturer.

Storefront Applications: Storefront systems are best suited for low-rise applications typically on the ground floor. However, they may be used on a second floor as long as the code and environmental conditions don't require higher structural and/or water management performance than is possible with these inherently limited systems. Storefront systems should never be stacked directly on top of each other and should not be used in upper stories of mid- to high-rise buildings. From a thermal performance standpoint, they are best used in situations where energy or comfort are not the first priority since they typically cannot perform as well thermally as other choices. Storefront systems are also quite appropriately used for interior applications such as shopping malls, schools, etc. where simple separation of conditioned space is sought.

Improper uses of storefront glazing. On the left, multiple layers stacked on top of each other create a water management problem with a high potential for failure. On the right, a storefront system stacked on top of a door system without the benefit of structural support between the doors creates a structural performance issue. Photo courtesy of Manko Window Systems, Inc.