BlockFlash is a complete, embeddable flashing solution for managing moisture in exterior, single-wythe CMU walls. It uses patented flashing pans to collect moisture in the wall and channel it to the exterior through integrated weep spouts. The spouts are gray in color to blend in with standard mortar. Drainage mesh placed in every block cell in the course immediately above the pans provides hundreds of clear pathways for water to flow around mortar droppings inside the cells, so it can be collected by the pans. Mortar Net’s BlockFlash cuts installation time associated with using membrane flashing in a multi-wythe course by approximately 50 percent and eliminates the need for multiple architectural CMU sizes that are typical with through-wall flashing.

BlockFlash for 6-inch CMU works the same as the 8-, 10- and 12-inch versions, which have been installed in over 3 million lineal feet of CMU walls. The 6-inch BlockFlash option was designed to meet the growing popularity of specifying 6-inch CMUs in building construction to meet future building energy codes and for its space-saving benefits in larger buildings.

For more information, visit and