Tags: #buildingdefects #buildingdesign #buildingmaterials #buildingscience #materialsscience #waterresistance

Wood-based WRB panels: Their behavior gets curiouser and curiouser as seen in this drying sequence of an exposed overlay. 

There are many ways to wet these panels. Contrary to prevailing assumptions, wetting occurs thru an intact overlay using conventional testing methods. Blemishes, fasteners, and panel joints are not required. Here, a ‘perfect’ panel was wetted with 5-hr hydrostatic pressure at 21.6 inches. Portions of the overlay were then removed to expose its bi-layer structure and the panel’s underlying strands. 

In this sequence, the observed drying occurred over 2.5 hours. But drying beneath an intact overlay requires considerably longer – not hours, but days. Just another reason why WRB panels should be evaluated on the basis of water entry into the panel, not through it. Apply this benchmark to all forms of testing – even the anemic measure of ASTM E331. 

“The hardest thing to explain is the glaringly evident which everybody has decided not to see.”

 ― Ayn Rand