Is your garden tree causing your home to sink?

Insurers paid out £66 million in subsidence claims to UK homeowners between July and September 2024 according to the ABI — an increase of 61% compared to the same period in 2023.

Climate change is a big factor contributing to the increase of weather-related insurance claims, but having a tree on your property can worsen the effects.

In particular subsidence, one of the more common and more expensive claims on home insurance, can be caused or worsened by trees.

What is subsidence?

Subsidence is when the ground underneath a property sinks, causing the foundation of the property to become unbalanced. This can cause cracks to form in walls and floors as the building is destabilised.

Similar to subsidence is heave, which is where the ground underneath a property expands, pushing the ground upwards.

Certain causes of subsidence unfortunately can’t be avoided and are down to location. Certain soil types make a property more prone to subsidence.

Cohesive soils like clay and silt are highly absorbent, so they can expand and shrink depending on if the weather is wet or dry. This regular shrinking and swelling can cause the foundation of the property to shift, creating cracks around the property.

Absorbent soil types can also cause heave – the opposite of subsidence – where the ground becomes waterlogged.

Cohesive soils are most common around the Capital and South East of England, but you can find out the specific soil type in your home area using the British Geological Survey map.

How do trees cause subsidence?

Certain types of trees can drink a considerable amount of water through their root systems. If their roots extend underneath a property they can cause the soil around them to dry out and shrink.

Moving a tree can also contribute to subsidence. Without them to absorb excess water from soil, areas where trees have been removed can flood or swell.

Certain trees might contribute more to subsidence when planted in cohesive soil, such as:

• English oak

• Willow

• Ash

• English elm

• Aspen

• White poplar

These types of trees thrive in wetter environments or have long and fine root systems.

Trees can add to property value but make insurance more expensive

Trees and other plants when mature and well maintained can add thousands to your property value, so there is good reason to have them.

However, they can be expensive to maintain, and homeowners should beware that trees and subsidence can impact the cost of home insurance.

The average price of home insurance is around £296 a year, but insuring a property that has evidence of subsidence or heave could cost an extra £220 a year or more.

Unfortunately , once you have subsidence insurers are always going to see you as a higher risk. But the right treatments can reduce further damage caused by heave or subsidence and save you from large claims and increasing insurance costs later on.

What can be done?

Catching the signs early-on can save you a lot of grief later on. Look out for:

• Cracks in walls both inside and outside

• Sinking or bulging floors

• Doors that stick or don't close

Removing the cause of the subsidence by correcting drainage issues or removing trees can prevent existing damage from getting any worse. In extreme cases, it may be necessary to have the property underpinned to reinforce the foundation.

If you took out home insurance before finding signs of subsidence, your home insurance policy may cover you for subsidence damage.

If you contact them right away, your insurer can arrange a full survey to confirm it and find the cause. However, most policies will have exclusions, so read your documents carefully or contact your insurer for more information.