How to minimise the risk of subsidence when planting trees and shrubs.

As we enjoy the warmer weather, we know that many of our clients will be keen to finally start enjoying their gardens. However, the hot weather can also bring on subsidence, where the ground loses moisture causing foundations to sink. This risk can be increased if clients are planting new trees and shrubs.

To help our clients minimise the risk of subsidence at their homes, Aviva Private Clients have put together the following advice:

Choose tree variety wisely: Information published by the ABI (Association of British Insurers) suggests that certain types of trees – including poplar, willow, elm and oak - are more likely to cause problems than others, due to their long, fine root structures. According to the National House Building Council, lower water-demand trees include birch, elder, hazel and magnolia. Residents may wish to consult an arborist for expert advice, if they are unsure about which varieties to plant.

Don’t plant trees or large shrubs close to your 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 a greater 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, get an expert to check.

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.

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.

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

Do not remove or modify a tree which has a preservation order, unless all the appropriate consents are obtained.

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. Sandy, gritty soils are more susceptible to this issue.

Check gutters and drainpipes too and make sure they’re well maintained; in case they are leaking.

Be particularly vigilant if clay soils are common in the region. Subsidence is more likely to occur in areas where clay soils are prevalent because they’re more prone to shrinking during hot weather. Clay soils are more common in southern England, so residents here are warned to be on their guard.

Don’t ignore existing vegetation. If unsure of an existing tree or shrub potentially causing damage, we suggest seeking advice from an experienced professional. A good source of information can be found here Arboricultural Association - Find a Professional (trees.org.uk)