You are probably thinking that the Subsidence Forum’s website is not the most likely place to see positive information on trees, but you’d be wrong! For some years now the Forum has been working behind the scenes to encourage a broader membership to join its ranks so that it can convey a better understanding of the issues around trees and tree related building subsidence to the general public and professions alike.
Its membership now includes tree experts and local authorities responsible for managing, in one way or another, most of the trees that are visible in and around our towns, cities and in rural areas too. It even has a special Tree Root Claims Liaison Sub-Group to look at how to improve the issues around dealing with tree related subsidence cases.
Generally speaking everyone loves trees and the benefits they bring. It is widely accepted that they improve people’s living and work space and provide beauty, shade and tranquillity when the relationship between them and the buildings that immediately surround them is a harmonious one. It is also widely accepted that under certain conditions trees can also cause problems with building’s foundations and real difficulties and concerns for the ordinary house owner.
These conditions are long periods of dry weather, with little, or no rainfall in areas, where the houses and buildings are built on a clay soil that shrinks in volume as it dries out. Trees and their roots can be very efficient at removing water from these types of soil and it is this simple relationship that causes a significant number of building subsidence cases to be tree related.
However not all trees cause subsidence and it is also practically impossible to predict which ones will or will not cause problems in the future. Many tree experts suggest keeping trees that are in close proximity to buildings on clay soils well pruned so that the leaves cannot remove more water from the soil than if it was just left to grow unchecked and unmanaged. There is evidence to show that this approach does work but that it must be done on a very regular basis to ensure that the tree does not continue to cause problems.
Increasingly and as a response to climate change the planting of trees is being promoted as a mechanism for dealing with the expected increases in temperature likely to occur in the future. These temperature increases will be exacerbated by the mass of the built environment in towns and cities. Central London is already some nine degrees warmer than the surrounding countryside on very hot summer days. In the longer term much of the traditional building stock like Victorian and Edwardian terraced housing and suburban buildings constructed during the 1930’s and 1950’s are likely to be particularly affected by this urban heat island effect due to their design and materials used in their construction.
Trees have the potential to make a significant contribution to improving and ameliorating the worst impacts of climate change in cities and town centres. However, they will only be able to fulfil this function if the benefits they bring outweigh the disadvantages that may occur by providing for their presence. The Subsidence Forum is committed to working hard to resolve these very difficult issues so that people’s homes and property are protected, repaired when necessary and that trees are not incorrectly identified as being the cause of the problem and are not removed unnecessarily when another course of action is effective, more appropriate and better for the environment.
Unit 28
