Wind-driven rain is a key source of moisture in the built environment: projections show that the climate emergency will cause extreme precipitation events to become more intense over the next 20 years. The project will use Computational Fluid Dynamics to study wind driven rain and water runoff from traditional building facades. The project aims to explore the relationship between wind driven rain, surface water runoff flow and key decay mechanisms of porous building fabric. The expected outcomes will improve forecast scenarios for traditional buildings, enabling more detailed simulation to inform adaptation strategies for a 21st century climate.