What is subsidence? Causes, signs and impact on insurance
Just the mention of the term subsidence could cause homeowners to panic, but what is subsidence, how can you identify the warning signs, and what does it mean for your home insurance? Find out more in this comprehensive guide.
What is subsidence?
Subsidence is an issue that affects the stability of a property. Subsidence occurs when the foundations of your property start to sink, as a result of problems with the ground below it. If the ground underneath your property starts to collapse, the structure of the building can be affected. For example, one side of the property may be affected more than the other, so your house could lean at an angle and/or cracks may start to appear in the walls.
What causes subsidence?
Subsidence is caused by problems with the ground underneath and around a property, when the soil becomes unstable. It can happen for various reasons, including the type of soil and the presence of excess water or trees.
Clay soil
Clay soil can be especially problematic because it reacts significantly to moisture changes.
- Shrinks when it gets too dry.
- Expands when it gets too wet.
- This movement causes the ground to shift, potentially affecting the property's foundations.
Excess water
Excess water from various sources can also lead to subsidence by saturating the ground.
- Caused by leaking drains or water mains.
- Saturation weakens the ground, leading to instability.
Trees and shrubs
Large trees or shrubs close to a property can contribute to subsidence due to their root systems.
- Roots grow under the ground and soak up water.
- This can dry out the soil, causing it to shift.
Heave (the opposite of subsidence)
Heave is like subsidence but involves the opposite movement. Instead of the ground sinking, it rises due to soil expansion.
- Heave occurs when the soil swells and expands, pushing the foundations upward.
- It can be just as problematic as subsidence, affecting the structural integrity of the property.
What are the signs of subsidence?
Here are some common signs that your property may have subsidence:
- Cracks in the walls: these cracks are usually wider than normal and run diagonally. They can appear both inside and outside the house and may get worse quickly.
- Doors and windows sticking: doors and windows might become hard to open or close as the foundation shifts.
- Uneven floors: floors might start to slope or feel uneven as the ground beneath moves.
- Gaps around window frames or doors: gaps can form around windows and doors as the walls shift.
Smaller cracks can appear naturally as a house settles, often due to temperature changes or newly plastered walls. These are usually less serious than subsidence cracks.
Does home insurance cover subsidence?
Many home insurance companies will include subsidence as part of their buildings insurance cover.
Although, subsidence may not always be covered by insurance. It may be excluded if it’s a pre-existing issue, which can be caused by poor maintenance (like leaks or tree roots), or involve fences, walls, or outbuildings. Some insurers don’t cover it at all, especially for high-risk properties. Always check your policy, as insurers sometimes include subsidence cover with an increased excess in the event of a claim, maintain your home, and consider specialist cover if needed.
My house is subsiding – what should I do?
If you suspect subsidence, contact your home insurance provider to check if you’re covered. Many home insurance policies include subsidence as part of their buildings insurance. If you’re covered, your insurer will guide you through the next steps. They may arrange for a surveyor to assess your property and monitor the situation to determine its severity. Minor repairs might resolve the issue, but serious cases could require underpinning to strengthen the foundations.
Keep in mind that most policies only cover fixing existing subsidence, not preventing future problems. When getting a new home insurance quote, always declare any history of subsidence. Failing to do so could affect future claims if subsidence occurs again.
How to reduce the risk of subsidence
To help reduce the risk of subsidence and protect your home, here are some simple steps you can take:
- Maintain your gutters: regularly clear debris from gutters to prevent water overflow that could affect the foundations.
- Unblock drains: check for blocked drains and clear them to avoid water buildup around the property.
- Manage trees and shrubs: avoid planting large trees too close to your home, as their roots can affect soil stability.
- Fix leaks quickly: repair plumbing leaks promptly to prevent water from weakening the ground around your foundations.
- Monitor soil levels: during dry spells, keep soil around your home moist to prevent it from shrinking and destabilising the foundation.
