Tags: #buildingenclosures #buildingenvelopes #buildingmaterials #buildingproducts #buildingscience #materialsscience #roguetesting

The saturated interface test: I’m revisiting this simple method as a means for evaluating water resistance of WRBs, building papers, and underlayments. 

This method employs a saturated slab of mineral wool as the moisture source. The wetted insulation is placed directly against the test specimen – in this case, an asphalt-saturated felt over a chaired MgO substrate. Instead of measuring the substrate moisture content, here I’m using rosin paper as a visual indicator of bulk water. 

Test duration is arbitrary. I recommend 24 hours, but curiosity often has me extending this to 7 days. 

It’s a quick but reliable method for evaluating water resistance. Incorporating tape and sealant interfaces is straightforward. And I often use it for evaluating adhesion of coatings and surfactant release.