Masonry Magazine June 2010 Page. 24
FLASHING & DRAINAGE
was generally eight inches, but with the wide use of 10-inch mortar collection grids, that height must be expanded to a minimum of 16 inches to assure the excess mortar stays below the top of the flashing material.
One of the most important details of the flashing installation is located on the outside of the wall. Some projects call for the flashing simply to be cut flush with the wall face after it has been completed. This most certainly will lead to a moisture-related problem over time. As water is carried to this edge, or rain is driven to it, you will see a capillary effect, where water is brought back into the wall underneath and behind the flashing materials. It is so important to have the flashing carry away from the wall face, as noted by the BIA and many other organizations. With a metal flashing, this can be accomplished by extending the flashing an inch or so from the face of the wall and turning it down to form a drip edge, though the aesthetic result is often less than desirable. With all flashing types, the better option is to use a premade drip edge, which has a greater uniformity and more options in its visual appeal. A drip edge also must be properly detailed. It should extend into the bricks a minimum of three inches, with the flashing material lapping over it completely, and sealed with the appropriate mastic. I urge caution when using metal drip edges with asphalt-based peel-and-stick flashings, however, as they tend to carry heat to the asphalt, making it soften and leach more quickly.
Shown is a flashing lap joint.
So where do flashings need to go? The answer is really quite simple: anywhere there is a horizontal interruption between the veneer and the backup. Most commonly, this occurs at the base of
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