Measurement of optimal thickness of radon-resistant materials for insulation using diffusion coefficient

The uses of waterproofing materials for insulation including required optimal thickness are discussed in this work. There exists a difference of five orders of magnitude in the diffusion coefficient of building materials along with the four orders of magnitude in the thickness and diffusion length. The radon resistance offered by materials varies with (a) thickness for given diffusion coefficient and (b) with diffusion coefficient with same thickness to diffusion length ratio (d/L). The earlier assumption of using thickness equal to three times of diffusion length is not workable for all materials but it causes an underestimation or overestimation.