Masonry Magazine December 2008 Page. 26
FLASHING AND DRAINAGE
WATER, WATER, EVERYWHERE?
Masonry walls have been around for a long time, and water has been around a lot longer. Problems occur when the latter interacts badly with the former and, as mason contractors know, preventing that bad interaction is an ongoing project.
BY TOM INGLESBY
WITH THE GROWING USE OF NEW MATERIALS AND PRODUCTS, SUCH AS STONE VENEER AND CONCRETE BRICKS, changes are developing in how drainage is provided and flashing is installed. Moving that ubiquitous water from entry to a non-damaging exit (providing proper drainage) is subject to a variety of factors, including the type of wall material, whether it is a single or double wythe, what the substrate is, and where, geographically, the building is positioned.
"In cavity wall construction, we like to have a continuous area for drainage and ventilation, meaning at no point is it obstructed with any element, mortar or other debris that may be getting put into the cavity," says Sarah B. Atkins, president of CavClear in Hudson, Wisc. "The most common thing that would obstruct the cavity, of course, is excess mortar that gets expressed into the cavity space during the construction of the exterior brick wall. Anything that blocks any air space or anything that is making contact with both the inside of the brick and the back-up or insulation or substrate is going to block moisture from being able to flow out of the system, and that impedes the ventilation of the cavity."
CavClear developed insulation and a masonry system intended to prevent mortar, in particular, from being able to make contact with the backup or substrate.
CavClear cavity walls have a continuous area for drainage and ventilation.