What Are the Different Types of Ground Movement?

Subsidence and other types of ground movement are one of the most serious threats to your property. With changing weather patterns and increasing dry spells, the risk is on the rise, especially during the warmer months. As homeowners, understanding subsidence, its causes, and how to reduce its impact is essential to safeguarding your property.

This guide will walk you through:

• What subsidence is and why it’s an issue 
• What causes it 
• How to reduce the risk of subsidence affecting your home 
• The different types of ground movement

This short guide will ensure you’ll be better equipped to identify potential problems and take proactive steps to protect your investment. 

What is Subsidence? 

Subsidence occurs when the ground beneath a building sinks, pulling the property’s foundations down with it. According to the Association of British Insurers (ABI), this usually happens due to the ground losing moisture and shrinking. Prolonged dry spells or the presence of water-hungry trees nearby are common culprits. 

When the soil beneath your home shifts or sinks unevenly, it can lead to visible damage, such as cracks in walls, floors, and ceilings. If left unchecked, subsidence can severely jeopardise the structural integrity of your home. 

What Causes Subsidence? 

Subsidence happens when the foundations of your property become unstable. The primary reasons include loss of moisture in the soil, eroded ground layers, and improper construction techniques. Below, we explore the main causes in detail. 

1. Clay Shrinkage 

Clay soils are particularly prone to subsidence due to their water content. Composed of 30-35% water, clay contracts as it dries out. This can happen during prolonged dry spells or if large trees and shrubs nearby absorb significant amounts of water from the soil. Clay shrinkage is one of the most common causes of subsidence in the UK. 

2. Trees and Shrubs 

While trees add beauty to your property, their roots can pose a risk. Large, mature trees and shrubs nearby might absorb vast amounts of moisture from the soil, leading to shrinkage and instability. Reducing or removing trees is often necessary, though you must take special care if legal or neighbourly considerations arise. Your insurer may help with these issues, including arranging for legal action if necessary. 

3. Escape of Water 

Leaking or burst pipes can wash away soil beneath your foundations, reducing their ability to support your home. This phenomenon is especially common with older drainage systems or prolonged leaks that remain undetected. Be mindful of early signs and get leaks repaired promptly.  

4. Erosion of Soil Under the Building 

Erosion caused by underground water movement or poor soil stability can create small cavities beneath your home’s foundations. Over time, these voids can collapse, forming sinkholes and causing sudden subsidence. This is often tied to limestone or chalky soil areas. 

5. Collapse of Underground Mines 

Properties built near historic mining sites are particularly vulnerable. Collapses in disused mines can weaken the ground’s stability, leading to subsidence. If your property is in a known mining area, your home insurance policy may factor this into potential claims. 

6. Poor Ground Preparation 

If a building’s foundations are constructed on improperly compacted or unstable soil, subsidence may occur. This can result from inadequate building techniques, such as using inappropriate materials or failing to stabilise the ground properly before construction. 

7. Decomposition of Organic Material 

Over time, organic matter naturally decomposes, causing the ground to lose volume. Known as “organic fill”, this is a particular problem in areas where construction has occurred on reclaimed or unstable land. 

8. Soil Type & Properties 

The type of soil beneath your property can significantly influence the likelihood of subsidence. 

• Clay Soil expands with excess moisture and cracks in hot weather
• Sandy or Chalky Soil is prone to erosion and washing away

Understanding your soil type can help you assess your subsidence risk and create a game plan. 

Reducing the Risk of Subsidence 

While some factors contributing to subsidence are beyond your control, there are practical steps you can take to reduce its likelihood and minimise damage to your property. 

Manage Trees and Shrubs 

• Avoid planting large trees or shrubs too close to your home. 
• Consult with tree surgeons to prune or manage existing trees safely. 
• For high-risk properties, consider installing root barriers to protect your foundations. 

Inspect and Maintain Drains and Pipes 

Regularly check for leaks or blockages in your water supply or drainage systems. Quick action to address water escapes can prevent soil erosion and widespread damage. 

Understand Your Soil and Foundations 

Ask a qualified surveyor to evaluate your property’s foundations and the soil it’s built on. For homes constructed on clay or sandy soil, specialist engineers might recommend reinforcement measures, such as underpinning the foundations. 

Choose the Right Building Practices 

If you’re planning an extension or major renovation, ensure the builder uses appropriate materials and techniques to support the structure. Cutting costs upfront can lead to long-term risks. 

Regular Home Maintenance 

• Look out for early warning signs of subsidence, such as cracks in walls larger than 3mm and diagonal in appearance
• Make note of windows or doors that jam or no longer fit properly
• Monitor nearby tree growth and water drainage regularly

Subsidence vs Other Types of Ground Movement 

Subsidence is often confused with other types of ground movement, such as heave, landslip, or settlement. Here’s a quick breakdown to help you identify the difference:

• Subsidence happens when the ground beneath a building sinks, pulling the foundations with it
• Heave occurs when the ground beneath expands, usually due to increased moisture, pushing the foundations upwards
• Landslip involves downward movement of a sloping area of ground, typically after heavy rain or erosion
• Settlement is a common and natural process where soil compacts under a building’s weight after construction, but does not necessarily indicate a structural issue

Act Early to Avoid Long-Term Damage: Choose Geobear Today

While subsidence can be intimidating, preventive care and early action can protect your home from long-term damage. By following the tips above and remaining vigilant for early warning signs, you can easily reduce the impact on your property and maintain its value. 

If you suspect subsidence or notice unusual changes in your home, choose Geobear for fast and effective underpinning services that will stand the test of time. We’re highly experienced in delivering unrivalled subsidence solutions to customers throughout the UK, whether domestic or commercial. 

If you’re experiencing subsidence in your property or have noticed some of the signs, then get in touch with a member of our friendly, professional team for subsidence investigations and solutions – we’re always proud to help.