ADOPTED_FROM:CEN ISO/TS 11665-12:2021 This document specifies the method intended for assessing the radon diffusion coefficient in waterproofing materials such as bitumen or polymeric membranes, coatings or paints, as well as assumptions and boundary conditions which will be met during the test. The test method described in this document allows to estimate the radon diffusion coefficient in the range of 10-5 m2/s to 10-12 m2/s[8][9] with an associated uncertainty from 10 % to 40 %.