Subsidence occurs when the ground beneath a building sinks, often due to changes in soil moisture levels. This can lead to foundation movement and visible damage, such as cracks in walls or uneven floors.

During the summer months many people will be turning their attention to gardening projects. Certain practices, particularly the planting of trees and large shrubs, can unintentionally increase the risk of subsidence and potentially compromise the structural integrity of your property.

To help combat this risk, we’ve compiled some practical guidance to help you make informed decisions when landscaping, particularly in areas where soil conditions or tree types may pose a higher risk.

 Smart planting tips

1. Choose tree varieties wisely – some trees have aggressive root systems that can draw large amounts of moisture from the soil, especially in clay-rich areas. According to the Association of British Insurers (ABI), species like poplar, willow, elm and oak are high-risk. Safer alternatives include birch, elder, hazel and magnolia. When in doubt, consult a qualified arborist. Further subsidence guidance from the ABI can be found here.
2. Mind the distance – avoid planting trees or large shrubs too close to the home, garage or outbuildings. Even a dense cluster of small hedge plants can have a significant impact. The safe distance depends on soil type, tree species and foundation depth – so expert advice is key.
3. Relocate young shrubs if needed – if a shrub was planted after the house was built and is still small, it may be possible to move it to a safer location.
4. Maintain existing trees – regular pruning, pollarding or thinning of branches can reduce a tree’s water demand, helping to maintain soil stability.
5. Monitor neighbouring trees – trees on nearby properties or public land can still affect your customer’s home. Make sure they keep an eye out for signs of movement or cracking and raise concerns with the relevant authority if needed.
6. Respect tree preservation orders – never remove or alter a protected tree without the proper permission.

 

Watch for water-related risks

• Leaky drains and pipes – water escaping from damaged drains can soften or wash away soil, especially in sandy areas.
• Gutters and downpipes – make sure these are well-maintained and not leaking near foundations.
• Clay soils – homes built on clay are more vulnerable to subsidence, particularly during hot, dry spells. This is especially relevant in southern England.

 

Source: Aviva