Tags: #architecture #buildingdesign #buildingenclosures #buildingenvelopes #buildingscience #coatings #flashings #materialsscience #water

Coated glass mat facers absorb water. But their absorptive characteristics vary. Some absorb a great deal of water and some do not. 

Why is this important if the facer is protected by coatings and liquid flashings? Because coatings and liquid flashings also absorb water, varying from greater than 5% (wt%) for seven-day immersion to over 30% for 30-day immersion! Combine this with insufficient thickness, discontinuity, surface pore structure, and leaching plasticizers and we have the makings for some interesting outcomes. When failures occur, the knee-jerk reaction is to hang the applicator – totally ignoring the synergy of failures that are actually in play.

The performance of WRB Systems must therefore consider not only all system components, it must also consider its substrate – something that is almost universally ignored. Glass mat facers offer challenges. And as we begin to evaluate water that enters the substrate, not just that which passes through it, the problems and solutions become more evident.