What is the impact of changing an assembly on its listing?

• A. It remains listing
• B. It remains listing if all materials meet ASTM specs
• C. Changing an assembly invalidates its listing, even if all materials meet ASTM specs
• D. It requires a minor update to listing

Answer: (C)

A listing is tied to a specific roofing assembly—the exact combination of materials, fasteners, substrates, and installation details that were tested together. Those tests prove how the system will perform under defined conditions. If you change any part of that assembly, you’re altering how the system behaves, so the tested performance can no longer be assumed. Even if every new component meets ASTM specifications, the interaction among parts and the overall performance (like wind uplift, moisture movement, and durability) can change. Therefore, the existing listing doesn’t apply to the modified configuration, and a new evaluation or listing approval is needed to certify the new assembly. In practice, this is why changing an assembly invalidates its listing, unless the governing listing body explicitly allows approved field substitutions.