Dealing with subsidence can be challenging for property owners, often leading to structural damage and reducing property value. In the UK, insurance companies receive over 20,000 subsidence claims annually. Understanding what causes subsidence issues and how to manage them is crucial for maintaining the integrity of your home. So let’s cover the basics of subsidence, its causes and warning signs, and how to proceed in the event your property is subsiding.
What is Subsidence?
Subsidence refers to the gradual sinking or settling of the ground, which can lead to the downward movement of a building’s foundation. This phenomenon can cause significant structural damage to properties, leading to visible cracks, uneven floors, and other issues. Identifying and addressing subsidence early is essential to prevent severe damage.
Causes of Subsidence
The reasons for subsidence can be broadly divided into natural and human-induced factors.
1. Natural Causes
- Soil Type and Composition: Certain soil types, such as clay and silt, are more prone to subsidence due to their shrink-swell capacity. Clay, for example, can expand when wet and contract when dry, causing the ground to shift.
- Natural Geological Movements: Earthquakes and sinkholes are natural geological events that can lead to sudden subsidence. These movements can cause immediate and severe foundation issues.
- Water Content in Soil: Fluctuations in soil moisture levels due to drought or heavy rain can cause the ground to contract or swell, leading to subsidence. Consistent moisture levels are crucial for soil stability.
2. Human Activities
- Construction Activities: Excavation, drilling, and other construction activities can disturb the soil and lead to subsidence. Improper construction practices exacerbate this risk.
- Mining Operations: Mining activities remove large volumes of underground material, which can lead to ground collapse and subsidence.
- Removal of Underground Water: Groundwater extraction can lower the water table, causing the soil to compact and settle.
- Poor Foundation Design and Construction: Inadequate foundation design and construction can fail to account for soil conditions, increasing the risk of subsidence.
Signs of Subsidence
Identifying subsidence early can mitigate the risk of severe structural damage, making it essential to be vigilant about changes in your property’s condition. Being aware of common signs as to what causes subsidence is key. Let’s explore some telltale indicators that every property owner should be familiar with.:
- Visible Cracks in Walls, Floors, and Ceilings: One of the most apparent signs of subsidence is the appearance of cracks, especially around doors and windows. These cracks are often seen around doors and windows, where the building’s framework is most stressed. They can start small but typically widen and extend over time as the subsidence progresses.
- Doors and Windows Sticking or Not Closing Properly: As the foundation shifts, it can cause door and window frames to become misaligned. This misalignment results in doors and windows that stick, jam, or no longer close properly.
- Tilting or Sinking Floors: Floors that appear uneven or sloping clearly indicate that the building is settling unevenly. This can often be felt as you walk across the floor, noticing areas that feel lower or more sloped than others. In severe cases, furniture and other items may visibly lean or slide towards the lower side of the room.
- Gaps Appearing Between Walls and Ceilings or Floors: Another significant indicator of subsidence is the formation of gaps where walls meet ceilings or floors. These gaps occur because as the foundation moves, the walls are pulled apart from the ceilings or floors, creating visible separations.
Being aware of these signs is the first step in diagnosing subsidence. If any of these symptoms are observed, it is essential to consult with a professional as soon as possible.
How to Reduce the Risk of Subsidence
Preventing subsidence is a highly effective and cost-saving measure compared to dealing with its aftermath. By taking proactive measures, property owners can significantly reduce the risk of subsidence affecting their buildings. Here are key strategies to minimise the likelihood of subsidence:
Drainage Systems
Taking consistent and thorough care of your property can help you spot potential issues before they become major problems. One common reason for subsidence is water gathering around the foundation, usually due to poor drainage. This can result in soil erosion, waterlogging, and increased soil shrinkage and swelling. To tackle this, it’s crucial to ensure efficient drainage and keep gutters and downspouts clean. Adjust the landscape to slope away from the foundation to direct water away from the building. Implementing proper drainage and soil stabilisation techniques can reduce the risk of subsidence by up to 50%.
Soil Management
Installing and regularly monitoring irrigation systems can help achieve even soil moisture, avoiding both overwatering and excessively dry conditions. Applying mulch around the foundation and in garden beds further helps retain soil moisture. Mulch acts as a barrier, reducing evaporation and helping to maintain stable moisture levels in the soil.
Additionally, be mindful of the types of plants and trees near your foundation. Large trees with extensive root systems can draw significant moisture from the soil, leading to shrinkage. Conversely, removing large amounts of vegetation can increase soil moisture. Therefore, choose plants with less aggressive root systems and ensure they are well-watered to maintain balanced soil moisture around your foundation.
Professional Inspections
Regular inspections by qualified professionals are essential for detecting early signs of subsidence and addressing them before they become severe. Having a professional inspect your property at least once a year is particularly important if your building is in an area prone to subsidence. These inspections can identify early warning signs such as minor cracks, changes in door and window alignment, and other subtle shifts.
Steps to Take When You Notice Subsidence
Managing subsidence effectively involves both immediate actions to prevent further damage and long-term solutions to ensure structural stability. Addressing subsidence promptly can mitigate severe damage and protect the integrity of your property.
Immediate Actions
It’s essential to take immediate action when signs of subsidence are detected. By implementing temporary supports and shoring, we can prevent further damage while we work on a permanent solution. These temporary measures are crucial in stabilizing the structure, offering immediate relief, and creating the time needed to devise and execute a comprehensive long-term strategy.
Long-Term Subsidence Solutions
To address subsidence permanently, underpinning techniques, drainage solutions and soil stabilisation methods can be employed.
Underpinning
Underpinning is a construction technique used to strengthen and stabilize the foundation of an existing building that has been affected by subsidence. Underpinning addresses this issue by extending the foundation to a more stable soil layer or by distributing the building’s load more evenly across the foundation. This ensures that the building is securely supported, reducing the risk of further movement or damage.
Consulting with a structural engineer or underpinning specialist is essential to determining the appropriate underpinning method and ensuring that the work is carried out correctly.
Grouting and Soil Nailing
Grouting involves injecting grout into the soil, which is effective in strengthening the soil and addressing voids. Soil nailing involves the insertion of steel nails at regular intervals to reinforce the soil. Both techniques are pivotal in preventing subsidence and ensuring the long-term stability of buildings.
Drainage Solutions
Installing proper drainage systems is essential to manage water levels around the foundation and prevent water-related subsidence. Effective drainage solutions can include French drains, sump pumps, and surface grading to ensure water flows away from the foundation rather than accumulating around it.
Professional Underpinning Services
Professional underpinning for subsidence offers numerous benefits, including increased structural stability and safety, ensuring that the building is secure. It prevents further damage by halting the progression of subsidence, thereby averting future issues.
If you suspect subsidence or need expert advice on managing it, Dart & Co is here to help. Our professional team specialises in underpinning and foundation solutions tailored to your needs. Contact us today for a consultation and ensure your property’s stability and safety.