What Causes Property Subsidence? Steps to Take To Stop Your Home Subsiding

When you buy a property, you think it's going to stand for decades, perhaps even hundreds of years. However, the earth beneath our feet is constantly shifting, and everything from unstable water tables to old mine workings, the type of soil, and even changes in weather and climate can destabilise even the most robust of properties.

Home subsidence is every homeowner's nightmare. Telltale cracks that appear around window frames, doors starting to stick, floorboards buckling and brickwork starting to separate can all point to a property suffering from subsidence.

This article provides an in-depth examination of the general causes, risks, and solutions associated with property subsidence. We’ll see how, even though it can be a worry, subsidence needn’t sound the death-knell for a property. We’ll also look at what to do if you suspect your home is suffering from subsidence, and how it can affect your ability to sell a property on, even if the issue has been resolved. We’ll also look at how your Insurance can cover the costs of repairs, giving you peace of mind that discovering you have home subsidence really isn’t the end of the world.

What is home subsidence?

Home subsidence is not the property moving or sinking; it's the ground underneath shifting. As it destabilises the foundations of the building, this becomes apparent through signs such as cracks appearing in brickwork, radiating cracks around the corners of windows and doorframes, doors sticking, and so on. If property subsidence is suspected, it needs to be addressed as quickly as possible. This starts with determining the cause of the subsidence.

What are the main causes of property subsidence?

There are numerous factors that can cause property subsidence, including soil type and environmental conditions.

• Clay or sandy soil – The type of soil you build a property on can have a significant influence on subsidence. For example, sandy soil tends to be unstable, while clay soil is prone to shrinkage, especially in prolonged hot, dry weather. With the UK now experiencing hotter, drier summers and many homes built on clay soils, the number of subsidence claims against home insurance policies is predicted to increase.
• Tree roots – Trees are thirsty: a mature oak tree can absorb up to 1,000 litres/day. As the roots search for and extract water from the ground and also grow underneath foundations, the resulting shift in the soil’s structure can lead to subsidence.
• Soil erosion – A leaking water or sewage pipe, a prolonged period of very heavy rain, or a change in the groundwater level can lead to soil erosion, washing away the soil underneath a building’s foundation and destabilising the building.
• Old mine workings – In some regions of the UK where extensive underground coal or mineral extraction has taken place, the voids left after the mines close can be a major cause of geographically specific subsidence issues, such as in the coal-mining areas of Yorkshire and south Wales.
• Poor or no foundations – Older buildings and particular types of structures, such as cobb cottages, often have inadequate or even no solid foundations. In contrast, new-builds located on constructed ground (piling earth and compacting it to form a building platform) may suffer from weakened foundations. This, in turn, can cause excessive movement, especially if environmental conditions destabilise the ground.

What are the signs of subsidence?

The most obvious sign to look out for when it comes to property subsidence is the presence of cracks in the walls. Look out for diagonal cracking near windows and doors, often radiating out from the corners. If a crack is wider than 3mm, it could be cause for concern. Cracks caused by subsidence are frequently wider at the top than at the bottom. If you're not sure if the cracks you notice are caused by subsidence, you can Google "What do subsidence cracks look like?” and compare the images to your own cracks.

Doors and windows that stick or are misaligned (you notice a gap that wasn't previously there, for example) can also be signs of subsidence, as are sloping or uneven floors. And if you notice your wallpaper starting to ripple or peel (and it's not due to dampness or any other reason), this can also be a sign that the building is shifting.

Could it be something else?

Subsidence is just one type of ground movement, so before you worry that your building is starting to shift, you need to determine that it's not another cause, such as settlement, heave, or landslip.

Settlement, also known as compaction, typically occurs within the first ten years after a building is constructed. It is literally the ground 'settling' due to the additional weight of the building, and it is quite common. If your home is a new-build, the cracks you see are generally milder and tend not to widen or expand.

Heave is the opposite of subsidence, and is when the ground moves upwards rather than sinking. This may be the result of the ground becoming saturated after a large tree has died or been removed, which can cause the soil to expand.

Landslips are most common in houses built on or near a slope, or as a result of soil erosion on one side that causes a change in the land's level.

How do I know what it is?

The best way to determine both the type of problem and its extent is to have a professional conduct a survey. However, if you want to claim for the cost of repairs on your insurance, it is best to notify your home insurance supplier, and they will arrange for the survey to be carried out. It's best to follow this route to ensure there are no issues if you do need to make a claim for repairs (more on insurance issues later).

What should I do?

There are lots of steps you can take to minimise the damage from home subsidence.

Initially, you need to contact your insurance provider and liaise with them to arrange for surveys and inspections to be carried out.

Active watching

In the meantime, you will need to monitor the situation (don't worry – unless it's extreme, such as an underground mining shaft giving way, your house is unlikely to collapse overnight!). If you are going to claim on your insurance, you'll need to document the situation from the moment you first notice any telltale signs, such as radial cracking.

The best way to do this is to write down measurements (including the dimensions and positions of cracks) and take lots of photographs. This ‘active watching’ process will give you an idea of how severe the subsidence potentially is, and it may even indicate that another cause, such as settlement, is the issue rather than property subsidence.

Talk to an expert

Although your insurance provider should handle all repairs for subsidence, you can initially contact an expert to request an assessment of your situation. They will be able to confirm whether it is subsidence or something else (such as settlement, heave, or landslip) and advise you on the best course of action. Any report they provide can be used to submit to your insurance provider, who will then pass the findings on to their own surveyors and assessors.

Minor subsidence may settle over time, but if the problem is more serious, it's crucial to take both preventative and curative action as soon as possible.

Take action

Once your insurance provider has agreed to the diagnosis of subsidence, it’s time to take action. If your problem has been caused by nearby tree roots destabilising the ground, you may have to remove the tree (if it’s on your land). You will need to check whether or not there is a preservation order on the tree before calling in the tree surgeons. If the tree is on someone else’s land, you will need to talk to them or their representatives to explain that the tree is causing a problem and damaging your property. A qualified tree surgeon will be able to advise on the best course of action.

If the subsidence has been caused by ground saturation due to a leaking water or sewage pipe, the first point of contact will be the utilities (if the leak is not on your property) or a plumber if the pipe is your responsibility.

In extreme cases, the foundations of your property may require strengthening using underpinning techniques. This is usually a 'last resort' option, as it is extremely costly and a long, complex process where the foundations of your home are stabilised using materials that are less susceptible to subsidence. You will need to liaise with your insurance provider, as the cost of underpinning may or may not be covered by your home buildings insurance.

If the subsidence has caused cracking in exterior or interior walls, you may also need to consult a builder to determine if these cracks can be repaired.

How much does subsidence repair cost?

It will entirely depend on the causes and extent of the problem. If home subsidence is caused by an easily fixable issue, such as a tree or a leaking pipe, then the cost shouldn't be too high. If, however, the cause is more serious, then underpinning may be necessary, and this can be extremely expensive.

Your home insurance should cover the costs of home subsidence, but you will need to follow a specific process, which will involve some financial outlay, such as surveyor's fees and expenses. As ignoring the problem could result in serious structural damage, it's far more cost-effective to address the issue than to ignore it – it won't simply 'get better' on its own.

Can I sell a property that’s suffered from subsidence?

You can, but you will need to disclose fully the property's history, the work carried out, and all surveyors' assessments to potential buyers. Demonstrating that you've been proactive in your approach to dealing with the situation will make it much more likely that you will be able to sell the property, as full disclosure will reassure potential buyers that the building is structurally sound.

Be mindful that a history of subsidence can depreciate a property's value by as much as 20%. With serious issues or a continued history of subsidence (for example, if the property is located in a mining area prone to ongoing subsidence due to underground collapses and voids), it may be challenging to sell the property.

Should I buy a property with a history of subsidence?

It will depend on the degree of subsidence. If the issue is caused by an easily fixable problem, such as a tree or a leaking pipe, then there is no reason why you shouldn't proceed with confidence. Do ensure, however, that the problem has been appropriately addressed and the cause of the subsidence dealt with thoroughly.

Buying a house with subsidence is always a risk, especially if the initial cause is more serious (such as the type of soil or historic mine workings). If you are interested in a property with a history of subsidence, ensure that there is proof of the repairs that have been carried out. Request to see the engineer's report, which will include information regarding the building's stability.

It's also worth obtaining a speculative insurance quote to determine if it includes any additional premiums or is classified as a high-risk property. You can also check the insurance levels for the area in general, which could indicate that the issue of property subsidence has a more general cause (and potentially a more long-term and difficult-to-fix one).

Finding the best subsidence insurance policy

Both commercial and property owners need to ensure that their buildings are insured against the cost of subsidence repairs, both minor and major. Subsidence is typically covered under standard building insurance, but if a property has a history of subsidence issues, it may be challenging for a new owner to obtain coverage.

The best way to find affordable and comprehensive cover is to talk to a broker. Remember that the key is full disclosure – if you do not tell your insurance provider that a property has a history of subsidence and that history comes to light if you then make a claim later on for the same problem, your insurance may not pay the costs of any new repairs. It pays to be completely honest about the property’s history when looking for insurance.

FAQs

Does building insurance cover subsidence?

Generally, yes. Building insurance does cover home subsidence or commercial property subsidence. The level of cover will depend on the building's history, as well as whether a claim for subsidence repairs has been made in the past.

How long do you have to declare subsidence?

There is no limit on the amount of time you have to declare subsidence to an insurer or potential buyer. It is part of the building’s history, so it has to be declared (regardless of the cause) to prevent issues with any future insurance claims or to ensure a sale is successful.

How do I reduce the risk of home subsidence?

Good maintenance will usually prevent more mundane causes, such as leaking pipes, overflowing gutters, blocked drains, or tree roots, from occurring. For more serious potential problems, such as soil type (clay or sand) or underground workings, it is best to consult a surveyor. Preventative measures are not typically covered by your property insurance, however.

Park Insurance – bringing some stability to your world

For over 30 years, Park Insurance has been providing the best in affordable, practical, and bespoke insurance to domestic and commercial property owners. We pride ourselves on our knowledge and experience, and the fact that we’ll never try to ‘upsell’ you insurance you don’t need. We understand that subsidence is nobody’s ‘fault’, so we will look for insurance that doesn’t penalise you financially if your home or commercial property has a history of subsidence. We use our position as preferred broker to some of the UK’s biggest insurance providers to find you a quote that’s right for you and your budget.

If you’re looking for insurance for a building that has been subjected to property subsidence in the past, talk to us today in complete confidence, or use our online Get A Quote button for an instant, no-obligation quote.