Performance Testing of Window Installation and Flashing Details

Abstract

Protection of interface at windows and other penetrations from rainwater intrusion is a primary need of building structures. This is especially true when the building is in a high weather exposure location or in a climate in which the ability for walls to dry may be limited. Two areas of specific concern are: 1) the bottom corners of windows where damage is most commonly seen, and 2) the area around curved, arched or round-top windows where it is difficult to install the standard flashing materials. This paper reviews performance testing of window flashing installation methods commonly used in the trade, as well as improved methods made possible by recent advancements in flashing products. A series of laboratory tests were designed to determine water resistance, air leakage resistance and durability of several installation methods with different flashing materials. Windows were installed in test wall sections using several methods. The installations were monitored and evaluated for ease of installation and then tested for air leakage and water resistance using ASTM E283 and ASTM E331. The durability of the installations was then evaluated by subjecting the walls to thermal cycling (0 to 160oF) and retesting for water resistance using ASTM E331. Recommendations for best practice installation based on the testing results and key material selection issues are presented.