Masonry Magazine September 2004 Page. 37
"People need to look at these systems in terms of the impacts they can have within a cavity wall structure." -Patrick Lee, Mortar Net
"I think the use of a system is an extremely good idea, but it needs to be more than a system for drainage, though," says Patrick Lee, Director of Sales for Mortar Net in Gary, Ind. "People need to look at these systems in terms of the impact they can have within a cavity wall structure. For instance, the whole idea of airflow, air management within the cavity, in addition to drainage."
Chris Bupp, Northeastern Sales Manager of Mortar Net, expands on this concept. "We talk about drainage, and that's one issue, but if you get moisture into that cavity, yes, you may drain liquid moisture out, but what's left are damp components that are in that cavity," says Bupp. "The idea is growing that the more airflow that you can get into that cavity to dry out those components, the better off you're going to be."
It's All About Airflow
WHO WOULD HAVE THOUGHT years ago that when we talked about drainage, we needed to, first and foremost, discuss the airflow in the cavity wall? Experts suggest that, without proper airflow, you may be able to drain the wall, but you won't dry out all of the moisture trapped in the wall system - and that means big troubles down the line. "[Mortar Net] completed moisture drainage testing a number of years ago, with the focus being the use of air and vapor barriers with cavity wall construction," says Bupp. "From these tests, we decided airflow is an equally important consideration when you're designing a drainage system. "What was kind of interesting was, when we first got into this thing, there had been very little testing done in the United States regarding weep vents and air flow," he continues. "Actually, the people to our north in Canada have done a little more testing on that type of thing. I ran across a testing application up in Canada where they tested weep vent products for airflow and found that a lot of the commonly used weep vent materials blocked considerable airflow into the cavity. So that was one of the things that led us to this whole airflow issue."
Weep Holes are lined with Weep Vents protecting the opening from clogging due to trapped debris
Basic Cavity Wall Design
Air/Vapor Barrier Insulation Board Wall Ties Synthetic Mesh Material with a Dovetail Shape and 90% Open Weave