Rainfall Clay and the Future of British Housing Foundations

In this episode of The Foundations of Building Surveying, I examine the extraordinary rainfall patterns affecting the UK in 2026 and explore what they mean for the hundreds of thousands of late-Victorian and interwar houses that define London and much of the South East. Drawing on rainfall data from the past 126 years, I explain how changing weather patterns, warmer air, and prolonged saturation are interacting with London Clay and other shrinkable soils.This is not a message of alarm but a professional assessment of risk. We look at how shallow foundations, traditional brickwork, suspended timber floors, and ageing roof coverings respond to persistent moisture. We also consider what may happen if a hot summer follows an exceptionally wet winter, and why insurers are likely already preparing for an increase in movement-related claims.Above all, this episode is about understanding mechanisms. Ground movement, clay softening, expansion, contraction, and the consequences of poor surface water management are not abstract concepts. They are physical processes affecting real buildings across the country. Good maintenance and informed observation remain the first line of defence.