A comparison of methods for determining watertightness test parameters of building façades

• Estimation of extreme weather conditions for any façade operating condition.
• Proper test parameters to assess watertightness of building façades.
• Critical comparison between two alternative methods for setting test parameters.
• Convergence verification of the results from both methods.
• Analysis of watertightness test parameters for a Spanish location.

Watertightness tests allow evaluating the performance of building façades using standardised parameters that simulate real weather conditions, i.e., a combination of wind-driven rain and driving rain wind pressure. It has been a challenge for researchers to experimentally test simultaneous wind and rain conditions in a rigorous manner. However, two new methods have minimised this problem, creating a precise relationship between the experimental result and the expected performance of the façade under real conditions and vice-versa. This article reviews both alternative methods and analyses their theoretical foundations and comparative advantages. In addition, the two methods are applied in the same case study, analysing the exposure conditions for a generic façade located in Bilbao (Spain). Ten-minute climatic records gathered over 14 years at the city airport have been used for this analysis. The comparative results show an adequate convergence between both procedures. However, their methodological differences would suggest using each one for different specific applications.