in short...

Trees should be regarded as real assets to our homes, however, occasionally they can cause problems to nearby (about 1.5m) structures. If you are concerned then contact us for professional advice.

the full answer...

Trees should be regarded as real assets to our homes and gardens for a multitude of reasons, not least because they are so beautiful. However, occasionally they can cause problems to nearby structures such as subsidence and other forms of structural damage.

If a tree grows very close (typically within 1.5m) of a lightly loaded wall or structure, then as it grows, the base of the stem or the large diameter roots very close to the trunk may exert pressure and cause it to collapse or lift.

If a house is founded upon a shrinkable clay soil, then trees may cause or add to movement damage because they draw water from the soil and cause it to dry out. Some trees require more moisture than others but all trees will require more moisture when they are fully grown with a large crown, so it is worth considering these aspects when planting new trees.

Trees growing close to drains and sewers may cause ‘direct’ damage if very close. At a greater distance it is common for tree roots to enter a pipe via an existing hole or gap and then to cause a blockage once the roots multiply. Where access is possible, clearing roots and inserting a flexible liner may solve the problem. This is mainly the case with old leaky drains; modern plastic drains are seldom affected.

The proximity of trees is often taken into consideration when a house is insured or valued. This does not necessarily mean that a tree poses a threat, but unfortunately, trees are often blamed for any movement in a building. If you have a tree that is close to a building or its foundations, it is always advisable to contact a professional tree surgeon to help you manage this risk and to manage the tree’s development both above and below ground.

Do trees cause subsidence?

The highest risk factor for any building with a tree in close proximity is the soil type. Generally clay soils are most prone to heave and subsidence, which are caused by the changes in water levels and are very prevalent in the London area. Clay soils can expand when a tree is removed because that tree would have drawn a high proportion of the moisture from the surrounding soil but is no longer there to do that, this is known as heave. Subsidence is the opposite of heave. This can be caused where a tree has grown to an extent that it is taking too much water from the soil, causing the clay to shrink and crack. This movement in the soil can cause problems with foundations, also known as subsidence. Again, professional tree surgeons can limit these effects by regularly maintaining the crown above ground through reduction, thereby managing the root system below ground, or in the case of heave, performing a phased/staged tree removal in order to allow the ground to adjust to the changes in water level over a period of time, before completely removing the tree.

Trees are not always planted in appropriate places, and the chosen species may not suitable for small town gardens. The mismanagement of trees over a long period of time may mean that tree pruning or tree reduction is not effective and removal and subsequent replanting may be the best option. We are always happy to discuss the options for replanting trees, where the removal of an existing tree is necessary. It is always possible to select and manage an appropriate species of tree or shrub in any size garden, with any level of light available to it.

In South West London locations such as Wandsworth, where space is limited, professional tree surgeons perform an important role, in managing trees and ensuring that they can thrive in urban areas without risking damage to properties. If tree surgeons were not able to manage trees effectively, then London would not enjoy the level of greenery of the diversity of species that we do.

Trees, shrubs and hedges play an important role in making such a congested, busy city, an enjoyable, pleasant and ecologically diverse place to live.

If you are concerned about a tree in Wimbledon or anywhere else in the South West London region our London based tree surgeons would be happy to advise on the tree work necessary and offer a free quotation.

Other questions and answers you may find useful

General Tree Surgery Questions

Specific to Take A Bough Questions