Glazed Over – a frame of reference

Picking back up with the exterior glass of the Visitor Center, we’ll take a look at the shop drawing submittals. The industry term for the glass units that fit in the aluminum framing is “Glazing.” The post on “Transparency-seeing through it all” focused on the glazing portion of the system. This time we will focus on the aluminum framing system that holds the glass in place.

The above image shows the north elevation of the Visitor Center and the corresponding shop drawing submittals for the large area of aluminum framing.

The combined glazing and aluminum framing system is addressed in 2 separate specification sections; “088000 Glazing” and “084116 Aluminum Entrances and Curtainwall.” The aluminum curtainwall is the large surface areas of glazing that are seen on the north and south sides of the building in the area of the Gallery space. These 2 large areas of glazing range 20-22 feet in height and nearly 30 feet wide on the north and some 56 feet wide on the south. The aluminum framing for these large areas are sections of aluminum that are 2 ½ inches wide by 11 ¼ inches deep. The individual rectangular openings of glass are 3 feet tall by 8 feet wide.

The above image shows the south elevation of the Visitor Center and the corresponding shop drawing submittals for the large area of aluminum framing.

Because of the large expanses these areas of framing and glass need to take on structural characteristics. The specifications require the manufacturer to design the framing system and submit calculations by a professional engineer to meet the following requirements:

• Wind loads per the structural drawings in the range of 10-13 pounds per square foot
• Maximum deflection perpendicular to the glass of 3/4 inch
• Maximum deflection parallel to the glass of 1/8 inch

Additional requirements include:

• Air infiltration limits
• Water penetration limits
• Thermal movement
• Condensation resistance
• Thermal conductivity

The above image shows the north elevation of the Visitor Center and the corresponding shop drawing submittals for the smaller areas of aluminum framing. These smaller openings do not have the same structural spans as the large areas and their sections of aluminum are correspondingly smaller with a 2 ½ inch width and 8 ¼ inches deep.

Standards for the industry are developed by organizations like ASTM and AAMA. These standards are referenced in the specifications to set forth performance and testing requirements. ASTM, the American Society for Testing and Materials now known as ASTM International sets forth industry standards for product quality and safety. These standards also help build consumer confidence. AAMA, the American Architectural Manufacturers Association has been around since 1936 and has developed standards focused on fenestration (exterior building glazing systems). Our specifications uses AAMA standards to set forth testing for some of the requirements listed above.

The completed aluminum framing installation is required to have a 10 year warranty for materials and workmanship and a 20 year warranty on the finish. Glazing and aluminum framing manufacturers take this all very seriously and continually test their products through organizations like ASTM and AAMA  to set standards of performance.