Although by no means the only cause, research over the years has estimated that around 60% of all subsidence problems with domestic houses, in clay subsoil areas, can be attributed to trees that are too close to the property, extracting moisture. Most trees have a significant radial root system, sometimes extending out a distance of 1 to 1.5 times the height of the tree.
One of the most common fears is that their roots will damage house foundations. In fact this is seldom the case as most foundations are able to withstand the odd tree root. But it is possible for roots to cause indirect damage through subsidence. Subsidence is what may happen to buildings on soils such as clay that shrink and expend in response to their moisture content. In summer, (or drought) clay soils shrink and in winter (or prolonged rain) they expand. This shrinkage and expansion causes movement, which may lead to subsidence. In some circumstances trees can make the situation worse.
In a large proportion of cases, offending tree(s) were within 16ft of the building and mostly all cases were where the damage was on “shrinkable” soils.
A few simple actions can be taken to protect your property and prevent long term problems if you live in a clay soil area are:
1.Do not plant trees or large shrubs close to the house or outbuildings – this table provides a guide to how far it is generally acceptable that species of trees can be planted.
2.Trees that are older than the property but within safe distances can be managed. Seek specialist advice from a tree surgeon or arboriculturalist – often maintenance programmes can be put in place to restrict growth by pollarding or crown thinning to control the amount of foliage produced, which in turn reduces the amount of water it requires
3.If trees are planted within the safe distance from your property after the house was built, it is recommended that they are removed, but never remove or in any way alter a tree that has a preservation order without the appropriate consent
4.The tree may be within a neighbouring garden or in the street. If you are worried about the potential subsidence problems, discuss it amicably and try to persuade then to take an appropriate action.
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For further information about how the proximity of trees can affect your household insurance, please contact Ben Butler 018 9165481 or complete one of our enquiry forms.