Flashing and Integration (Or Lack Thereof) of Windows with Weather-Resistive Barriers

November 29, 2006
Publication: Walls & Ceilings

Abstract: Lack of integration between windows and the building weather-resistive barrier is a systemic problem in many buildings that often leads to leakage within a wall system. Consequences of improper integration typically include leakage, damage to interior finishes and deterioration of wall components, such as sheathing and framing. Our investigation of numerous building envelopes across the country reveals a high occurrence of wall failures stemming from deficiencies in window flashing and integration between windows (both flanged and non-flanged) and the weather-resistive wall barrier. These failures can be avoided through the execution of a properly designed, step-by-step process of window and flashing installation. The proof testing of full-scale mock-ups and follow-up testing during construction have shown these techniques to be successful. This paper presents our investigative findings regarding window/wall integration failures, as well as our recommendations, and guidelines for flashing and integrating both flanged and non-flanged windows with weather-resistive barriers. We also include a review of current industry standards regarding window installation and compare our recommendations to these standards.