To view this page ensure that Adobe Flash Player version 11.1.0 or greater is installed.

TO VENT OR Not to Vent… Deciding on which strategy is best for attic applications by Mason Knowles Photo courtesy CertainTeed FOR DECADES, DESIGNERS OF ATTICS AND CRAWL SPACES HAVE USED CROSS-VENTILATION TO MINIMIZE THE POTENTIAL FOR MOISTURE ACCUMULATION AND CONDENSATION. HOWEVER, SPURRED BY RECENT CLAIMS OF ENERGY SAVINGS AND MOISTURE CONTROL, UNVENTED ATTICS HAVE BECOME POPULAR IN BOTH RESIDENTIAL AND COMMERCIAL APPLICATIONS. WHILE THESE ATTICS CAN BE USED IN MANY CIRCUMSTANCES, THIS AUTHOR BELIEVES THERE ARE REASONS TO USE VENTED ASSEMBLIES IN MANY SITUATIONS. Traditional methods of insulation materials and design call for using air circulation within the attic space to assist in drying excess moisture. In heating and cooling climates, this moisture could potentially travel through fiber insulation in building cavities. The traditional remedy to this wetting is to slow the influx of moisture-laden air into the cavity by using an interior vapor retarder, and by ventilating the roof cavity to the exterior in order to facilitate the carry off of moisture (i.e. drying). When done correctly, attic venting can reduce the potential for condensation in winter and summer. During winter, the primary cause of attic moisture issues stem from warm moist air infiltrating into the 32 the construction specifier | july 2013 CS_July2013.indd 32 6/14/13 8:28:00 AM