Best practices for applying commercial IGU glazing

Seattle Convention Center's curtainwall system uses IGUs.
Photo © Elena Vlasova | Dreamstime.com

By Amy Becker

Building occupants and residents can enjoy the daylighting, great views, and comfort provided by commercial fenestration. Given continual advances in glazing technology, specifiers need expert resources to select the most optimal glazing systems for their projects. The Fenestration and Glazing Industry Alliance (FGIA) has updated the IGMA TM-3000, North American Glazing Guidelines for Sealed Insulated Glass Units for Commercial and Residential Use, which can be used for this purpose.

Armed with a detailed understanding of the different components, how they are manufactured and integrated into glazing systems, testing standards, and more, specifiers can make informed decisions when it comes to selecting insulated glazing units (IGUs).

IGU performance standards

Before delving into some relevant technical details in the updated standard, it is worth pointing out the long-term thermal performance of a complete fenestration system depends upon the overall performance and durability of its IGU. To best ensure performance, 101/I.S.2/A440-22, North American Fenestration Standard/Specification for windows, doors, and skylights (NAFS) requires fenestration IGUs to meet ASTM E2190 requirements and be certified by the National Fenestration Rating Council (NFRC) for thermal performance. This is also a requirement of the U.S. Environmental Protection Agency’s (EPA’s) ENERGY STAR program.

For NFRC certification, FGIA offers the following three programs:

  • Associated Laboratories, Inc. (ALI) AAMA Sealed Insulating Glass Certification Program
  • IGMA of Canada (IGMAC) Certification Program
  • Insulating Glass Certification Council (IGCC)/IGMA Insulating Glass Certification Program

A glossary of terms including definitions of the words clearances, fins, framing, glazing gasket, and heel and toe beads.Returning to IGMA TM-3000, the updated standard covers considerations for glass types, framing, clearances, setting blocks, spacer shims, glazing materials, glazing systems, storage and handling, glass protection, and cleaning for both double- and triple-glazed IGUs.

The document is all inclusive, addressing every aspect of glazing systems from soup to nuts. The comprehensive guide walks manufacturers, fabricators, specifiers, and contractors through all the glazing system components, addressing important points to consider, and things for which to look out.

Most helpful for specifiers are the sections on glazing materials and glazing systems where a detailed understanding is provided on all aspects and types of systems.

Glazing materials

The glazing materials section in IGMA TM-3000 largely focuses on sealants. For glazing systems, this typically includes silicones, polysulfides, polyurethanes, acrylics, latex, and butyls applied as gunned-in-place glazing sealants. Applications include sash joinery sealants, such as seam sealers, back bedding sealants, exterior weather sealants, heel and toe beads, butt-joint sealants, interior air seals, and structural glazing sealants.

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