Masonry Magazine August 2008 Page. 36
AIR BARRIERS
Photo courtesy of PROSOCO
Air barrier installation is typically straight forward, such as rolling or spraying the barrier onto the wall.
"increased the surface area of the moisture, it's going to dry faster."
CavClear prevents excess mortar from blocking weep holes, allowing moisture to pass through the wall properly, she says. It also provides protection against mold, mildew and other moisture-related problems, and it can be used with other air barriers.
"CavClear lets air and water flow through the air space for good drainage and ventilation," Atkins says. "If you're building with brick, a product like ours is going to provide ventilation to the air space behind it and prevent moisture-related failures."
Understanding and installing air barriers
Air barrier installation is typically straightforward, such as rolling or spraying the barrier onto the wall, so masonry contractors can install it while building masonry walls.
"The masonry contractor is typically the installer of air barriers since the mason is erecting the block walls, then they're applying the brick façade," Polk says.
Even if masonry contractors don't apply the air barriers, they need to understand how the systems work, Henry says.
"It's important for a masonry contractor to be well educated about all aspects of the wall," Henry says. "The masonry contractor has to know what's going on with the wall, so he knows how to respond if there's a problem."
For example, if he notices the air barrier coming loose before he starts laying brick, he'll know there's a problem that can lead to moisture and mold.
"The masonry contractor has to realize he could be one of the first people who gets blamed if there's a problem, even if he had nothing to do with it," Henry says. "He could fairly quickly put investigators right, but who needs to spend time doing that to begin with?"
If the masonry contractor spots a problem, he can inform the general contractor, he adds. "Like it or not, the masonry contractor is going to have some connection to the way that wall performs."
34 Masonry
August 2008 www.masoncontractors.org
PRODUCT WATCH
Air/vapor Barrier Choice
By Christopher Bupp
As energy costs continue to increase, the use of air/vapor barriers becomes more critical to today's design environment. The ability to make a building as airtight and energy efficient as possible is a major consideration in building envelope design.
Air/vapor barriers can come in a number of types, depending on the design, geographic location and intended purpose of the barrier. The major criterion for an air/vapor barrier system is the ease of application to make the system totally continuous with no gaps or points at which air or vapor could penetrate the system. Sheet membranes have been popular in the past, due to their factory-controlled thickness and quality control. However, fluid-applied products are becoming increasingly popular today, due to their ease and speed of application. CMU backup wall systems lend themselves to fluid-applied materials, while steel stud with gypsum sheathing assemblies effectively can use both sheet and fluid-applied systems.
Because of these factors, Hohmann & Barnard has introduced both sheet and fluid-applied air/vapor barriers to best handle both wall designs. Sheet membranes include TextroFlash, a 40-mil. rubberized asphalt peel-n-stick product, plus Textro Flash Green, also a 40-mil. membrane that uses a pressure-sensitive, adhesive technology that includes about 45 percent post-industrial recycled content to qualify this product as being green. It can contribute toward achievement of LEED standards. Both of these sheet membrane products are non-breathable air and vapor barriers.
Fluid-applied products include Textro Flash Liquid and Textro Flash Liquid VP. Both of these products are VOC-free (Volatile Organic Compounds) and HAPs-free (Hazardous Air Pollutants), making them environmentally friendly. Textro Flash Liquid is a non-breathable air/vapor barrier that is applied at a 40-mill thickness. Textro Flash Liquid VP is a similar material but is breathable, to allow proper drainage and promote drying of the wall cavity in both directions. Both products can be spray or brush applied down to 20 degrees Fahrenheit and rising, and can be applied to the recommended 40 mil. thickness in one coat. IMAS
The Voice of the Masonry Industry