What is subsidence and other types of ground movement?
Ground movement can damage a building because it impacts the ground it is constructed on. Your home or buildings insurance policy might refer to ‘the site’ of the property. This is the prepared ground that the property is built on, after the foundation trenches have been dug.
The main types of ground movement are:
- subsidence - when the ground beneath a building sinks, pulling the foundations down with it
- heave - upward movement of the ground beneath a building when the soil expands
- landslip - downward movement of sloping ground
- settlement - downward movement caused by the weight of the building compressing the soil within 10 years of construction
Settlement is sometimes also called ‘consolidation’ or ‘compaction’. Most home insurance policies cover subsidence, heave and landslip. Some commercial property insurance policies also cover these things.
Subsidence usually happens when the ground loses moisture and shrinks. The volume of the soil reduces and the building’s foundations subside (sink down). This is usually caused by one of the following things.
Clay shrinkage happens when soil with a high clay content dries out. Clay is about 30% to 35% water. It can dry out because of nearby plants absorbing the water. This can happen during prolonged dry spells. Clay shrinkage is one of the most common causes of subsidence.
Trees can sometimes cause subsidence because their roots absorb water from the ground. Your insurer might ask a tree surgeon to cut back the tree, install root barriers or cut the tree down.
Sometimes a case might involve a third party, like a neighbour. Your insurer can take legal action against them if they won’t allow their trees to be reduced or removed. But we’d expect the insurer to:
- speak to you about this first
- think about the impact this might have on your relationship with your neighbour
- pay for the legal action
If the insurer takes legal action, we’d expect you to co-operate.
Your insurer can’t force a neighbour to do anything about their trees without taking legal action. If the insurer doesn’t take legal action, we’d expect them to find another way to solve the problem and repair any damage. If you don’t let the insurer take legal action, we might not ask them to find another way to solve the problem.
An escape of water is usually caused by burst or leaking pipes. A significant or long-term escape of water can wash away particles in the soil. This can cause subsidence because it reduces the volume of the soil. It could also soften the soil and reduce its ability to support the building. This can also cause subsidence.
Your policy might have an ‘escape of water peril clause’. This means your insurer will look at your claim under this clause at first, not under subsidence. Usually this has a lower excess. However, sometimes subsidence is excluded from escape of water claims. This means you might have to pay a higher excess if you claim.
When the soil under a building erodes, it can create an underground cavern. This is called a ‘sinkhole’ also known as ‘solution feature’. Eventually, this gives way and causes subsidence. It’s often caused by water and can occur in limestone or chalky soil. The first sign of a solution feature is usually a small hole appearing at surface level.
If an underground mine collapses, it can cause subsidence. This includes disused mines. Sometimes in these cases, a third party might be responsible for the damage. However, the insurer should still deal with your claim. They might work with the third party to sort out the loss or damage.
Every property will ‘settle’ after it is built. This happens because the weight of the building compacts the soil underneath the foundations. However, this can be made worse by poor ground, leading to subsidence. Poor ground might be a result of:
- inappropriate material used by the builders
- builders not compacting the ground material properly
- the way the ground is prepared before construction starts
Any of these can lead to subsidence. We often see cases where floor slabs have subsided because of problems with the fill underneath them. This fill is not considered to be part of the site. Because of this, most policies exclude subsidence of floor slabs if there’s no movement of the foundations as well.
As organic fill in the soil decomposes it loses volume and resilience. This can cause subsidence.
Types of complaint we see
We see complaints about a range of issues to do with ground movement cases. You might complain to us if:
- your insurer has rejected a subsidence claim and says the damage was caused by a different type of ground movement that you weren’t insured for
- the claim is taking too long to resolve
- the insurer isn’t communicating with you
- the insurer isn’t providing adequate alternative accommodation while your home is being repaired
- you don’t think the insurer is doing enough to repair the damage
- you’re not happy with the standard of the repairs
- the repairs have caused more damage
- the insurer won’t continue your cover after a subsidence claim
How to complain
Talk to your insurer first so they have the chance to put things right. They have to respond within eight weeks. If they don’t respond, or you’re not happy with their response, let us know.
Bringing a complaint to us is straightforward and won’t cost you anything. We’ll check if your complaint is something we can deal with, and if it is, we’ll investigate.
What we look at
One of the first things we look at is the type of ground movement that damaged your property. These cases can be very complicated. We’ll need to see expert evidence and technical data. We’ll need to look at the symptoms of the problem to find out what caused it.
We’ll also check that the insurer has investigated the problem thoroughly. Sometimes this involves monitoring the situation over a year so that all the seasons are covered. A thorough investigation would usually involve:
- digging shallow holes to find out how deep the foundations are, what they rest on and if any nearby drains are leaking
- digging deeper holes (boreholes) to look at the ground and get samples for analysis
- video inspection of nearby drains
We’d also expect your insurer to monitor any cracks in the building. This is to check:
- if the building is still moving
- how bad the movement is
- whether the movement is seasonal
Read more detail about what we look at in specific types of complaint:
Many policies don’t cover damage to other parts of your property unless your main residence is also affected. This includes things like:
Policies differ in how they define the main residence. Some include outbuildings like sheds and garages, but some don’t. We often see complaints about this. However, as long as the policy is clear about what’s included we don’t see this as a problem. This means we don’t expect the insurer to tell you about this specifically. When we look at a complaint, we’ll check the policy documents to see exactly what’s covered.
We see cases where customers have changed their insurer, then claimed for subsidence. The new insurer says the subsidence happened before the new policy started. It says the subsidence should be covered by the previous insurer, but the previous insurer doesn’t agree.
The Association of British Insurers has a Domestic Subsidence Agreement. If your insurer has signed up to this, they have to handle your claim in a certain way. The rules are:
- if you claim eight weeks or fewer after the start of your current policy, the previous insurer deals with the claim
- if you claim one year or more from the start of your current policy, the current insurer deals with the claim
You might claim more than eight weeks after the start of your current policy, but less than a year after it started. If this happens, whichever insurer you first told about the claim has to deal with it. Both insurers will share the cost. It doesn’t matter whether the damage happened before your current policy started.
Your insurer might cancel your current policy if you knew about subsidence when you took it out but didn’t say anything.
Some problems with properties look like they are caused by ground movement. However, they are caused by other things.
Sulphate damage is sometimes mistaken for heave. It’s caused by a chemical reaction between cement paste in a concrete floor slab and sulphates in the filling under the slab. The chemical reaction is usually triggered by water. Policies don’t usually cover sulphate damage unless it’s caused by an insured event - for example, a leak from a water tank.
All properties suffer from cracking, but if your home has cracks, it doesn’t automatically mean you have subsidence. Cracking can be caused by:
- settlement of the building - most buildings settle in the first few years after being built
- poor design, materials or workmanship
- failure of a lintel - the support for the brickwork above a window or door
- expansion and contraction caused by changes in temperature (‘thermal movement’)
Your policy might not cover these things.
We’ll treat your complaint the same way as other disputes about claims under home insurance policies.
We expect repairs to be effective and lasting. This means they must:
- fully put right the damage
- last for an appropriate amount of time - for example, a rebuilt wall should last for decades, but basic decorations might only last for a few years
Sometimes the only way for a repair to be effective and lasting is to carry out work on damage that isn’t covered under the policy. In situations like this we expect the insurer to carry out this work even if it’s not written in the policy.
We’ll look at expert opinions about the repair and the actions your insurer has taken. We’ll sometimes ask for further independent advice.
We see complaints where the insurer has agreed to a repair and stops payments once the maximum amount has been reached, even if the work isn’t finished. In most cases like this, the insurer has entered into a contract to repair. This is separate from the contract of insurance. In this situation we’re likely to tell the insurer to continue to pay for the repair, even if it’s more than the maximum amount in the policy.
Sometimes the cost of repairs is greater or almost greater than the amount a customer has insured their building for.
If your property is beyond economic repair, the insurer might offer you compensation instead. This represents the reduction in the property’s value. It’s worked out based on the value of the property before the damage, minus the value of the property after it the damage. Your insurer must calculate this using expert evidence - for example, from surveyors or estate agents.
Sometimes customers complain that a property’s value has decreased even after it has been repaired and the movement has been stopped. They ask the insurer for extra compensation. In cases like this we’d normally say that if the property has been stabilised and repaired, there shouldn’t be a reduction in value and compensation isn’t needed.
Putting things right
If we think your insurer has treated you unfairly or made a mistake, we’ll ask them to put things right. We’d expect them to put you in the position you would have been in if the problem hadn’t happened. How we ask them to do this will depend on the case. There’s no single way to settle complaints about claims relating to ground movement.
We may also ask the insurer to pay you interest, or to pay you compensation if you’ve been caused distress or inconvenience.
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Information for financial businesses
You can read more information about subsidence and other types of ground movement in the business section of our website. This includes technical details and information to help you resolve complaints.