Storefront (Glazing System)

The Full Picture

Storefront is the glass-and-metal wall seen at the ground floor of retail, office lobbies, schools and clinics. It is assembled from aluminum extrusions (head, sill, vertical mullions and sometimes horizontal rails) that hold glass lites and, usually, one or more entrance doors. The frame is typically fastened inside a rough opening or to the structure around it, and it normally spans a single story. That is the main practical difference from curtain wall, which is usually anchored at the floor slab edges and can run past multiple stories. The Fenestration and Glazing Industry Alliance (FGIA) publishes separate documents for the two, listing SFM-1 as the Aluminum Storefront and Entrance Manual and CW-DG-1 as the Aluminum Curtain Wall Design Guide Manual.

Install variants change both the detail and the price. The glass can sit toward the exterior (front-set), in the middle (center-set) or toward the interior (back-set) of the frame depth, and each pairing changes the extrusion and the flashing. Glass can be captured by pressure plates or glazed from the inside or outside with stops, and some designs use silicone-glazed vertical or horizontal joints for a flush look. Systems are sold as stick-built, where pieces are cut and assembled on site, or as shop-assembled frames set as units. Thermal breaks, insulated glass and low-e coatings are specified where the opening is part of the thermal envelope. Wind pressure is the governing concern for the glass: the National Glass Association says the major design concern for an exterior wall is wind load pressure, and that thickness analysis for entrances is essentially the same as for storefront.

In the documents, storefront shows up on the exterior elevations and the floor plans, in a window and storefront type schedule or glazing legend, and in wall sections and head, jamb and sill details. The specification is in Division 08 (Openings), which often also covers the entrance doors, hardware and glass types. Safety glazing near doors, performance requirements such as wind load and air or water infiltration, finish and color of the anodized or painted aluminum, and the allowance for field measurement all come from that section. The architect may also show a storefront-to-wall flashing or sill pan in the envelope details, which is where scope is often split between the glazing sub, the sheet metal sub and the waterproofing or masonry trade.

Estimators usually count a storefront by the opening and then break it into pieces. Gross opening area in square feet gives a first sanity check, and linear feet of vertical and horizontal framing, the number of lites by size and glass type, and doors and hardware each get their own lines. Perimeter sealant is carried in linear feet, often on both the interior and exterior sides. Pitfalls are consistent: carrying the frame but not the doors, leaving out upgrades such as tempered or laminated glass and low-e coatings, ignoring the sill pan and flashing, and treating a multi-story glass wall as storefront when it needs a curtain wall quote. Field measurement and lead time also matter, because glass is often ordered only after the frame openings are verified.