Hull sits on deep alluvial deposits from the Humber estuary, with soft clays and silts extending over 30 metres in many areas. The city's history of land reclamation and flood defence works means the ground can vary significantly within a single site. We've seen cases where a seemingly uniform clay layer hides peat lenses or buried channels that reduce shear strength drastically. That's why a proper factor of safety calculation here isn't a formality — it's a necessity. Before we assign a design FS, we always run a study of soil mechanics to profile the stratigraphy, and when dealing with existing fills we often use test pits and exploratory pits to visually inspect the materials. Our team works to Eurocode 7 partial factors, adjusting the global FS based on the actual variability of the ground, not textbook assumptions.
For soft clays under high water table, we rarely recommend an FS below 2.5 for shallow foundations — site-specific analysis is non-negotiable.