Masonry Magazine August 2008 Page. 34
AIR BARRIERS
CavClear is made with a non-woven plastic mesh and is designed to have water drain through not absorb. Photo courtesy of CClea
Air barriers stop air from moving through the wall cavity.
"That warm moist air is going to try to find its way to the cold dry air," Henry says. "It will try to get out any hole, like penetrations in the wall." Air barriers stop that air from moving through the wall cavity, he says.
Managing moisture with air barriers
AIR BARRIERS NEED four things to be effective, otherwise they can make the moisture condition worse, Henry says. They have to be continuous, so air doesn't escape at seams; durable so they stay in place until the brick is installed; breathable so vapor can pass through; and structural so they adhere to the sheathing and can't detach from it.
Epro Services has an air barrier membrane called Ecoflex that can be rolled or sprayed onto buildings. The barrier is placed in wall cavities of commercial buildings, like schools, between the CMU and the brick façade, Polk says.
Ecoflex is self-sealing and adheres to almost any substrate, including damp block, to prevent air leakage. It also seals leaks caused by penetrations in the wall and cracking due to building movement and shrinkage, Polk says. Ecoflex comes in both a permeable and non-permeable formulation.
Hudson, Wis.-based Archovations Inc. makes air space maintenance and drainage materials, called CavClear, that help manage moisture in masonry construction, according to Sarah Atkins, company president.
"Our products are made with a non-woven plastic mesh. They're designed to have water drain through them, not absorb the water," Atkins says, explaining that CavClear spreads out moisture along the fibers. "Because you've now 32 Masonry August 2008 www.masoncontractors.org
Air Barrier LEED Credits
Some air barriers qualify for Leadership in Energy and Environmental Design (LEED) credits.
"Advanced Building Products is in the process of changing Vape-R-Seal air barrier products to a more environment friendly air barrier system," says Keith Lolley, VP for the Sp vale, Maine-based company. "We hope to have it available by fall. The air barrier will be manufactured from recycled mater which will qualify for LEED credits, and be compatible with o systems in the market."
CavClear products also qualify for LEED credits, says Sa Atkins, president of Archovations Inc. in Hudson, Wis. CavCle made from 100 percent recycled plastic. The sheets help m tain thermal efficiency in buildings besides helping elimi moisture in walls. IMAS The Voice of the Masonry Industry