Combined use of wind-driven rain and wind pressure to define water penetration risk into building façades: The Spanish case

• Comprehensive assessment of water penetration risk for building façades.
• Analysis of driving rain wind pressure in Spain.
• Climate research of daily climate data from 80 Spanish weather stations.
• Development of a risk index map for water penetration of Spanish façades.
• Improvement of the current Spanish standard for the façade system selection.

This article defines a new index to characterise the risk of atmospheric water penetration into building enclosures. This risk index integrates the two most relevant exposure parameters for this phenomenon into a single value, combining the water supply presented by driving rain and simultaneous wind pressure on the surface of the enclosure. Compared with the usual wind-driven rain exposure maps, the inclusion of driving rain wind pressure in this index permits a more complete assessment of the risk of penetration. Therefore, this index represents a powerful tool for defining more appropriate façade solutions for exposures that result in atmospheric water penetration. This risk index was calculated for 80 Spanish sites scattered around the Iberian Peninsula and the Canary and Balearic Islands using daily precipitation averages and wind speed averages for each location collected over 30 years. As a result, a risk index map has been produced for Spain. The risk characterisation obtained in this study enables an objective improvement of current Spanish building regulations governing the design of façades against the penetration of atmospheric water.