2. Wall and decoration

To determine the diffusion resistance R _D of a paint film, or more generally of a waterproofing system, we need to know the system's intrinsic permeance: (π /e ) _s (in g/m ² · h · mmHg).

In fact, both official test reports and technical documents supplied by manufacturers express the permeance of the test specimen coated with the system: (π /e ) _r in g/m ² · 24 h.

This can be explained as follows: on the one hand, steam flow measurements are carried out over a 24-hour period (low mass loss of the wet cup); on the other, the pressure gradient is a function of the temperatures at which the tests are carried out (in...