Rationale

To: Subcommittee C16.20 and Main Committee C16 members From: Doug Fast, Chair, Task Group for C1902 Subject: C1902 Standard Specification for Cellular Glass Insulation Used in Building and Roof Applications Work Item No.: WK78792 Date: April 23, 2026 Ballot Rationale – Include definition of “boards” to ASTM C1902 “Standard Specification for Cellular Glass Insulation Used in Building and Roof Applications.” This will provide clarification and consistency with ASTM C552 “Standard Specification for Cellular Glass Thermal Insulation.” The current version of ASTM C1902 “Standard Specification for Cellular Glass Insulation Used in Building and Roof Applications” refers primarily to “block” insulation defined within the specification under “Terminology” section 3.2.1. However, there are also references to “boards” within the specification which isn’t defined within the standard nor does the ASTM C168 definition of “board insulation”, shown below, accurately describe the nature of cellular glass. “board insulation, n – semirigid insulation preformed into rectangular units having a degree of suppleness particularly related to their geometric dimensions.” A more relevant definition of “board” insulation with respect to cellular glass insulation is shown below. 3.2.2 board, n - fabricated flat, rectangular units composed of cellular glass block insulation adhered together and covered with a facing adhered to one or both major faces. Please note, the related sections are shown for context, only the highlighted changes, (red and crossed out items) are being balloted. With this update the term “thermal insulating materials-board” would be added to the keyword section of the standard. Regards: Doug Fast Phone: +1 720 508 9362 Email: doug.fast@owenscorning.com 3. Terminology 3.1 For definitions used in this specification, see Terminology C168. 3.2 Definitions of Terms Specific to This Standard: 3.2.1 block, n—unfaced cellular glass. 3.2.2 board, n - fabricated flat, rectangular units composed of cellular glass block insulation adhered together and covered with a facing adhered to one or both major faces. 18. Keywords 18.1 building insulation; cellular glass; cellular materials; cellular materials preformed thermal insulation; insulation blocks; manufacturing process; physical properties; roof decks; roof insulation; thermal insulating materials; thermal insulating materials-block; thermal insulating materials glass; thermal insulation; thermal insulating materials-board