The Fenestration and Glazing Industry Alliance (FGIA) has released an updated technical specification addressing the design and manufacture of multiple-cavity insulating glass units (IGUs), reflecting the growing demand for higher-performance, energy-efficient glazing solutions.

The updated document, IGMA TM-1300-26 – Design Considerations for Multiple-Cavity Insulating Glass Units, provides guidance on the key technical and quality considerations that must be taken into account when designing, fabricating, and using IGUs with more than one sealed cavity. The document replaces the previous edition last updated in 2013.

As energy regulations tighten and performance expectations rise across residential and commercial construction, multiple-cavity IGUs are increasingly specified to achieve improved thermal insulation and overall system efficiency. While adding cavities can significantly enhance performance, it also introduces additional complexity in terms of design, manufacturing control, and long-term durability.

IGMA TM-1300-26 addresses these challenges by outlining recommended practices related to cavity configuration, material compatibility, fabrication processes, and quality requirements of the sealed spaces within multiple-cavity units. The guideline is intended to support professionals across the fenestration supply chain, including designers, specifiers, fabricators, and installers.

Commenting on the update, Amy Becker, FGIA Glass Products Specialist and staff liaison for the Design Considerations for Multiple-Cavity IGUs Task Group, highlighted the industry’s ongoing shift toward higher-performance glazing. She noted that increasing the number of cavities is an effective method to improve energy efficiency, but one that requires careful attention to new technical considerations. The updated guidelines aim to help industry professionals navigate these challenges more effectively.

The revised specification is now available through the FGIA online store, with pricing set at USD 80 for FGIA members and USD 230 for non-members. FGIA also recommends complementary reference documents, including IGMA TM-3000 – North American Glazing Guidelines for Sealed Insulating Glass Units for Commercial and Residential Use, for a broader technical framework.