London Subsidence Repairs. Clay Shrink and Swell and Foundation Slippage

SubsidenceLtd have over 30 years of construction experience in many different aspects of domestic home and property repair. We supply all customers with a 10 year warranty and pride ourselves on the best customer service in the subsidence repair industry.

Soil Types: London Clay and Subsidence Repairs

Understanding the relationship between subsidence and soil types is crucial for homeowners in the UK.

Much of Southern England lies atop deposits of London Clay, Oxford Clay, Gault Clay, and Weald Clay – dense, overconsolidated sedimentary clays deposited in ancient seabeds. Their high montmorillonite content allows substantial shrinking and swelling with moisture changes.

This characteristic significantly impacts the structural integrity of buildings and other constructions in these areas in times of droughts.

London Clay can be quite deep, with thicknesses varying significantly across the region. It underlies much of London and the surrounding areas.

Cracks in the Walls: A Stark Reminder of the Montmorillonite-Clay Tango

The telltale signs of montmorillonite’s influence are often etched in the form of cracks in walls. These cracks can be:

Vertical: Indicating settlement or upward pressure from the expanding clay.
Horizontal: Suggesting movement within the wall itself, potentially due to differential settlement.
Diagonal: Pointing to potential rotational movement of the structure due to uneven foundation movement.

Mitigating the Hidden Menace Under Your Home

While montmorillonite poses challenges, it’s not an insurmountable foe. Various measures can be taken to reduce its impact on home foundations slippage and moving over the decades.

Broken drain detection: Ensuring efficient rainwater removal prevents the clay from becoming overly saturated and expanding. We send CCTV cameras down your drains which carry water to and from your home. Over 50% of subsidence jobs are caused by fractured water pipes, not tree roots as we previously mentioned.

Foundation Repairs with Foam: Deep foundations or piling techniques can anchor structures below the zone of clay movement. Resin foam injection is not considered a true piling technique by definition, but it can serve as an alternative to piling in a lot of situations. Structural repairs are for extreme cases.

Monitoring Wall Cracks: Regular inspections to keep tabs on the crack width are strongly recommended. If the crack is wider than the width and proactive repairs can address minor cracks before they evolve into major issues.

Modern techniques like resin injection are increasingly favoured for their ability to effectively address these challenges, and being an eco-friendly alternative to structural underpinning.

Resin Foam Injection: Subsidence Repairs In One Day

Traditional underpinning is still useful for serious subsidence, but modern resin injection often provides an efficient, less invasive alternative.

Liquid resins permeate soils and expand to reinforce weak areas without digging. Resin stabilisation restores structural integrity with less cost and disruption than underpinning – making it ideal for Britain’s common subsidence soil types.

London Clay is a type of blue-grey clay, which was deposited during the Eocene epoch, approximately 50 million years ago. The Eocene epoch was significant for the emergence and evolution of many mammal species, which began to fill ecological niches as dinosaurs were extinct 10 million years previously.

The Clay covers much of the London Basin and extends beyond the city. This clay is known for its high plasticity due to its composition, which includes minerals like montmorillonite that are highly reactive to changes in moisture. The relationship between London Clay and property foundation slippage, especially in areas close to the River Thames, is a significant concern for homeowners and construction professionals like SubsidenceLtd.

Borehole sampling, ground-penetrating radar, and lab tests determine soil engineering properties. With detailed soil profiles, structural solutions address the unique conditions and adjust the resin mix accordingly.

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