Drainage and Drying in Low- and Mid-Rise External Walls
|Reasons for Moisture Management|
|Drainable Housewrap Installed on Ocean-front House|
Designed for “Leadership in Energy and Environmental Design” (LEED®) certification by George Penniman Architects, LLC and constructed by Evergreen Building Systems, LLC, the 4,500-sq. ft. water front home in Westerly, R.I. required moisture management that met the demands of significant ocean exposure.
A drainable housewrap with 1 mm spacers to provide water drainage and channeling was installed. “The product is robust enough that it can withstand the high winds of a waterfront location before it is covered,” says Michael O’Neill, Principal, Evergreen Building Systems. “It’s easy to work with and the shingles lay flat on it.”
Selecting Effective Housewraps
While the need for a solution that prevents moisture infiltration and permits drainage is clear, some confusion still abounds when it comes to selecting the right solution for each project. One reason is terminology. Product names such as housewraps, water resistive barriers, fluid-applied and self-adhered WRBs, and even building papers are frequently interchanged. Another is that housewraps are now available in dozens of varieties. Most are woven or nonwoven plastic fabrics made from either polyethylene or polypropylene. Some have micro-perforations to let water vapor pass through and others are designed to let water vapor diffuse through the fabric itself (micro-porous). In order for design professionals to make the most appropriate and effective choice, they should be familiar with the characteristics of housewraps.