Fire resistive curtain wall helps mixed-use residential building meet property line requirements

Project Name: The Kensington, Boston
Architect: TAT
Glazing contractor: Cheviot Corporation
Products supplied: SuperLite II-XL 60 insulated with Solarban 70XL in SAFTIfire CW Framing

The majority of fire rated glazing applications occur inside the building in order to allow occupants to exit the building safely or provide an area of refuge during a fire. But what happens when the threat of fire comes from the outside?

This was the case for The Kensington, a mixed-use residential building in Boston. The west-facing elevation was in close proximity to the property line, prompting the building official to require part of the curtain wall to meet ASTM E-119/NFPA 251/UL263 for 60 minutes. In addition, the fire rated curtain wall had to match the rest of the non-rated systems seamlessly, as well as pass the rigorous dynamic testing prescribed by CDC (Curtain Wall Design and Consulting), the firm hired by the architect to ensure that the building was air and water tight.

To meet these requirements, SAFTI FIRST supplied SuperLite II-XL 60 insulated with Solarban 70XL in SAFTIfire CW Framing in a continuous span from the seventh to the tenth floor, with a segmented portion at the center, per the architect’s design. The aluminum covers used in the SAFTIfire CW Framing System had a champagne metallic finish and mimicked the appearance of an aluminum pressure wall, easily matching the non-rated exterior glazing systems. The ability to incorporate Solarban 70XL also contributed to meeting an average U-value no more than 0.40 and a solar heat gain coefficient no greater than 0.25 as required in the specifications. Since the SAFTIfire CW Framing system is thermally broken, it is a natural selection for exterior fire resistive applications in places that experience extreme weather like the Northeast.

In addition, the system was subjected to dynamic curtain wall testing designed to replicate real world conditions. An independent test lab was hired to perform the following tests, which SAFTI FIRST’s CW Framing System successfully passed:

• Air Infiltration, ASTM E 283-04, Rate of Air Leakage Through Exterior Windows, Curtain Walls and Doors.
• Static Pressure Water Resistance, ASTM E 331-00, Standard Test Method for Metal Curtain Walls and Doors by Uniform Static Air Pressure Difference.
• Dynamic Water Pressure Resistance, AAMA 501.1-05, Standard Test Method for Metal Curtain Walls and Doors by Uniform Dynamic Pressure.
• Structural Performance, ASTM E 330-2, Structural Performance of Exterior Windows, Curtain Walls, and Doors by Uniform Static Air Pressure Difference.
• Seismic Movement, AAMA 501.4-09, Recommended Static Test Method for Evaluating Curtain Wall and Storefront Systems Subjects to Seismic and Wind Induced Interstory Drifts.
• Thermal Cycling and Condensation Evaluation.
• Interstory Vertical Displacement Tests.

The SAFTIfire CW Framing System’s documented performance ensures that architects have a proven option for clear, unobstructed views when faced with property line requirements or other scenarios where the threat of fire comes from the outside.