A Comprehensive Approach to Facade Design for Preventing Rainwater Penetration: Implementation in Spanish Regions

Rainwater penetration into building facades results in multiple issues, including material and structural degradation, reduced energy efficiency, and health-related concerns among occupants. Currently, the watertightness performance of building facades is assessed based on standardized tests, which simulate generic water supplies and pressure differentials that do not reflect the specific exposure conditions of each facade. Consequently, practitioners’ decisions regarding facade design often rely on qualitative and imprecise criteria that do not align with the actual climatic loads. In this article, a comprehensive approach to facade design for preventing rainwater penetration is described, incorporating specific methodological refinements for reliable and practical implementation across various Spanish regions. In this approach, the parameters surpassed during any watertightness test (defined by the magnitude and duration of the water supplies and pressure differentials) are correlated with the recurrence of equivalent climatic exposures at the facade (determined by the climatic conditions of the site, facade height, and surrounding environment), thereby quantitatively characterizing the facade watertightness performance. The findings used to refine this method for implementation in Spain are illustrated and validated using selected case studies, and a comprehensive database is provided to enable its application at 360 locations distributed across various regions of the country.