Insurer explains how to minimise subsidence risks when doing garden makeovers

Keen gardeners are being warned by a major insurer to consider subsidence risks when planting trees and shrubs near their home.

Research conducted for Aviva suggests that around a third (33%) of people with some outside space across the UK are expecting to plant new trees, hedges or shrubs this year.

The UK heatwave seen last summer has fuelled concerns about the risks of subsidence.

In March, the Association of British Insurers (ABI) said its members expect to pay out £219 million for subsidence claims made in 2022.

This would be the highest annual subsidence payout since 2006, when the total was £301 million.

Figures from Aviva’s “building future communities” research indicate more than a third (36%) of UK residents are concerned about subsidence at their home, while a quarter (26%) are specifically worried that trees near to their buildings may lead to this issue.

More than 2,000 people across the UK were surveyed by Censuswide in March for Aviva.

Waseem Malik, chief claims officer for Aviva UK&I General Insurance, said: “The vast majority of homes and gardens can co-exist quite happily without plants causing problems to properties.

“However, nature can be incredibly powerful and trees and shrubs will go to extreme lengths to find the water they need to survive during hot spells.

“In turn, the surrounding ground can become incredibly dry and unstable if plants have removed excessive moisture. In extreme cases, this can lead to subsidence for nearby buildings.

“Prevention is the best cure, so we are encouraging gardeners to think carefully if they intend to start planting this year, to ensure their homes and gardens are climate-ready.

“Trees and shrubs can be beautiful additions to gardens, but they can grow to such proportions both above and below the surface. This can cause all manner of problems if they are planted too close to structures.

“We’d urge people to do a bit of research before they start making changes to their outdoor spaces, to avoid any issues further down the line.”

Ahead of the RHS Chelsea Flower Show 2023 (May 23 to 27), Aviva is offering some tips to help gardeners minimise the risk of subsidence:

1. Choose your tree variety wisely

Information published by the ABI suggests that certain types of trees – including poplar, willow, elm and oak – could be more likely to cause problems than others, due to their long, fine root structures. People may wish to consult an expert for advice, if they are unsure about which varieties to plant.

 2. Avoid planting trees or large shrubs close to buildings

Most people will think about their home, but the same applies to garages and outbuildings. Also remember, that a cluster of smaller, individual hedge plants can have more of an impact when grouped together. A suitable distance will depend on the type of subsoil, variety of tree and depth of foundations, so if in any doubt, again, check with an expert.

3. Consider whether shrubs could be moved if they are too close to a property

If a shrub was planted after the home was built and is still relatively small, it may be possible to reposition them elsewhere.

4. Maintain trees by pollarding or thinning their branches

This will reduce the amount of water they require and will therefore allow moisture to remain in the soil.

5. Keep a close eye on trees close to your property or garden

If a tree is in the street or on a neighbouring property, it is still possible to affect your home or outbuildings if positioned close to your structures, so be mindful of any signs of shifting or cracking.

6. Do not remove or modify a tree that has a preservation order, unless you have all the appropriate consents

7. In addition to keeping an eye on trees and shrubs, watch out for leaky drains

Leaks from drains or water mains can also lead to issues as they can soften soil or even wash it away, causing the land to sink downwards. Sandy, gritty soils are more susceptible to this issue.

Also, check your gutters and drainpipes too and make sure they are well maintained.

8. Be particularly vigilant in areas where clay soils are common

Subsidence may be more likely to occur in areas where clay soils are prevalent, because they are more prone to shrinking during hot weather. Clay soils are often more common in southern England.