The Gypsum Association has published the following clarification to GA-216-2016, Specification for the Application and Finishing of Gypsum Panel Products:
REPLACE THE TEXT IN 2.2.12.4 ON PAGE 3 WITH THE FOLLOWING:
"2.2.12.4 Where studs complying with ASTM C645 are used to receive abuse resistant or impact resistant gypsum panels, they shall be not less than 0.0312 in. (0.792 mm) design thickness and shall be in accordance with sections 4.3 and 8.1 of Specification C645."
This clarifies that 30 mil studs (20-gauge drywall) meet the requirements. The previous language used base metal thickness.