What is Subsidence?
Subsidence is a problem that occurs when the ground beneath foundations moves, causing the property above to shift, crack, sink or settle unevenly. It can result in significant structural damage if it’s not identified early and treated correctly, so it’s important to know how to spot the signs of subsidence. If you have subsidence problems, investing in modern resin injections can help you avoid extensive repairs and maintain structural integrity.
Key Takeaways | Cracks in Walls & What They Mean
Situation/Sign |
What It Means |
What To Do |
|---|---|---|
| Hairline cracks (<1mm) | Usually harmless, due to minor settling | Monitor for any changes |
| Cracks wider than 3mm, diagonal/stepped | Possible subsidence or heave | Seek professional assessment |
| Cracks near doors/windows, or sticking frames | Structural movement, foundation shift likely | Get expert advice |
| Multiple or widening cracks | Problem may be worsening | Take immediate action |
| Trees/large shrubs near property | Increased risk due to soil moisture removal | Consider tree management |
| Signs of water leaks/drainage issues | Soil erosion, higher subsidence risk | Inspect and repair plumbing |
| Built on clay or past mining area | Naturally higher subsidence risk | Use our postcode checker, monitor closely |
| Cosmetic vertical cracks | Often non-structural, plaster shrinkage | Fill and repaint if no change |
Remember, early assessment prevents costly damage, so contact a specialist if you’re unsure.
Common Causes & Signs of Subsidence
For lots of homeowners in the UK, the first signs of subsidence are subtle, often cracks in the walls, sticking doors and windows or shifting floorboards. However, if these signs are overlooked, subsidence will continue to get worse and can result in costly repair work being required. Recognising the signs of subsidence in a house and being aware of the common causes is essential for protecting your biggest investment.
Soil Type and Ground Conditions
Properties built on certain types of soil, such as clay and silt soils, are most at risk of subsidence. These soils expand and contract with moisture variations, typically shrinking during dry weather conditions and swelling after heavy rainfall, which can destabilise foundations. South East England and London are known for their clay soils, making homes more vulnerable.
Impact of Tree Roots and Vegetation
Any trees or large shrubs near your home can absorb water from the soil, causing it to dry out and shrink, increasing the risk of movement. Factors such as the type of tree species, the size of the tree, the proximity to your property, and the weather conditions will all impact how much of an impact it has on your foundations.
Water Leaks and Drainage Issues
Leaking drains and burst underground pipes are common problems, and they can cause more structural problems than you may think. The water can wash away or erode the supporting soil under the foundations, and over time, this will weaken the ground and increase the chance of subsidence. This is often more of an issue in older properties.
Construction, Foundations & Nearby Activity
When a property is built, the quality of the construction will have lasting effects. Shallow or inadequate foundations will increase the chances of shifting over time, resulting in subsidence. There’s a chance that vibrations from nearby building work or heavy traffic will also cause damage. Extended properties with different foundation depths are particularly susceptible.
Former Mining or Industrial Sites
Homes built in former or current mining regions, or on reclaimed industrial land, are more likely to experience subsidence. The historic activities in these areas can impact the ground conditions, and some homes will even sit directly above disturbed soils, voids or fill materials that are prone to shifting. You can check if a property is in a former coal mining area on the Government website.
How to Identify Subsidence
Knowing the early signs of subsidence can help you identify and address any structural issues before they cause significant damage.
Cracks in the Walls Inside Your House
When it comes to cracks in the walls, some are just cosmetic flaws that are straightforward to fix with some DIY, while others are the first signs of subsidence. Hairline cracks under 1mm are often the result of drying plaster, minor settling or subtle seasonal changes. It’s beneficial to monitor these cracks to make sure they don’t get worse over time.
The types of cracks you need to be wary of include: cracks that run diagonally or have a stepped pattern, as well as cracks that are wider at the top. If a crack is bigger than 3mm, especially if it appears suddenly or is near vulnerable areas like doors, windows or joints where extensions meet main buildings, it’s a potential sign of structural movement. These internal signs of subsidence should be professionally assessed and treated if required.
Find out more about subsidence cracks with our guide to problem cracks in walls.
External Signs of Subsidence
Externally, subsidence can appear in similar but often more dramatic ways. Look for diagonal or stepped cracks running through the brickwork, as well as visible separation between mortar joints. These can be signs that the bricks are moving due to subsidence.
Shifting or tilting of porches, extensions, or conservatories, and door frames or windowsills pulling away from the main structure are all indications that unstable ground may be affecting the foundation of your home. These external signs shouldn’t be overlooked, as they usually point to significant underlying movement in the soil.
Subsidence, Settlement, or Heave?
It’s important to know the difference between subsidence, settlement, and heave to decide the right course of action. Subsidence involves a moving foundation as a result of shrinking and swelling soil, often identified by diagonal cracks that are wider at the top, with doors and windows starting to stick as the frames shift. Whereas, settlement is a uniform and gradual downward movement that typically happens soon after construction. It’s rarely a cause for concern, unless the movement becomes uneven.
Heave is the opposite of subsidence, where the ground sinks. It’s when the foundation of a property lifts due to expanding soil, commonly caused by increased moisture, whether it’s a period of prolonged wet weather or a mature tree being removed.
Signs often include lifting patios or paths, warped door or window frames, and cracks in brickwork that are wider at the bottom. Understanding these differences will help ensure quick and accurate remedial work for each of these structural problems.
Subsidence Postcode Checker
If you’re worried about living in a subsidence-prone area, you can use our subsidence postcode checker to see local hotspots and recent cases. Simply enter your postcode to see how many projects Subsidence Ltd has completed in your area. This checker can be particularly useful if you’re considering buying a property in a new area, so you can assess the risk of subsidence.
The Impact of Seasonal Changes on Subsidence in UK Homes
The cycle of weather in the UK can impact the soil beneath properties. During dry summers, the soil dries and shrinks, then in wet winters it swells, increasing the likelihood of movement. Over time, seasonal changes can undermine the stability of a home’s foundations, leading to cracks becoming bigger, often around Christmas and New Year.
Postcode Hotspots for Subsidence in England and Wales
London has particularly high rates of subsidence, typically due to properties being built on layers of clay, silt and sand deposited by the River Thames over thousands of years. Many areas in Southern England are impacted by dense, over consolidated sedimentary clays like London Clay, Oxford Clay, Gault Clay and Weald Clay too. Building on these ‘shrink-swell’ clays can increase the likelihood of subsidence.
The clay-rich soils and seasonal weather variations also impact properties in the South Wales Valleys. Not to mention, the rich mining heritage can make subsidence issues more common. Old mining tunnels and shafts create voids that can collapse, impacting current land stability and causing subsidence above ground.
How to Fix Subsidence
Traditionally, underpinning was the most popular solution for fixing subsidence; however, this is no longer the case. Resin injections have now replaced this outdated, invasive and time-consuming method, providing an innovative way to treat subsidence.
Resin injection involves drilling small holes into the ground beneath a property and injecting a specialised resin material that will expand, filling voids, stabilising the foundation and supporting the structure. The whole process can typically be completed in one day, often with no need for planning permission or major disruption.
This modern solution is highly effective, offering a long-lasting solution to subsidence problems. It creates a stable foundation that can withstand further shifts in soil, offering peace of mind for years to come.
Often, the results of resin injection are immediate too, from closing cracks to more aligned windows or doors. Unlike traditional underpinning, resin injection doesn’t require excavations. It’s far less invasive and much more convenient. Not to mention, significantly more cost-effective, reducing both labour and material expenses.
The versatility of resin injections makes this method suitable for a wide range of properties and ground conditions, making it an ideal solution for various subsidence scenarios.
By using eco-friendly materials and techniques, the whole process is more environmentally conscious too, which is undeniably important in today’s modern world.
How Much Will it Cost to Repair Subsidence?
There isn’t a one-size-fits-all answer to this question, as no two subsidence repairs are the same. The cost of the project will depend on the size, location and severity of the problem. However, at Subsidence Ltd, we provide transparent pricing, offering a detailed cost breakdown before work begins, so you will know exactly what you’re paying for.
More often than not, resin injection is more affordable than traditional underpinning methods. You can get an insight into the different costs involved and request an estimate quote for the subsidence repairs on our website today.
What Happens if You Don’t Treat Subsidence?
While most subsidence problems start with minor cosmetic damage, such as cracks in internal walls, they can quickly escalate into more serious structural concerns that undermine the integrity of your property. Over time, the continued movement of the ground can cause cracks in the walls to widen and deepen, impacting the structural skeleton that supports the entire house.
Doors and windows will gradually become misaligned and harder to open and close, compromising the safety and security of your family. As the foundation continues to shift, floors may start sloping too and water can begin pooling in unexpected areas, increasing the risks of persistent damp and rot, impacting both comfort and health.
Ultimately, ignoring subsidence can cause extensive structural damage, potentially resulting in your home becoming unsafe or even uninhabitable. This will have a knock-on effect on the value of your property, making it incredibly difficult to sell in the future. Acting quickly as soon as you spot the first signs of subsidence is always the most effective way to minimise repair costs, protect your home and keep your family safe.
CEO of Subsidence Ltd
