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Current building regulations mean developers have to take account of nearby trees when drawing up plans.
Current building regulations mean developers have to take account of nearby trees when drawing up plans. Photograph: Andrew McRobb/Kew/PA
Current building regulations mean developers have to take account of nearby trees when drawing up plans. Photograph: Andrew McRobb/Kew/PA

Our dream home has been extended near trees – is subsidence a risk?

This article is more than 7 years old

We are very concerned to find out whether the builders factored the neighbour’s trees into their work

Q My husband and I are looking to move into a bigger house as our current two-bed, one-bath house has become too small for us.

We have found our dream home. It is a semi-detached property with three bedrooms and three bathrooms, which was rebuilt out of a rundown two-bed house in 2015. The previous owner extended the house to the side all the way up to the neighbour’s boundary wall. What worries me is that the neighbour has a line of very tall conifer trees running along this wall. I am afraid these trees could cause us a great deal of subsidence trouble in future – although there don’t currently seem to be any signs of subsidence in the house.

Would the construction company that did the work have had to account for these trees in some way – for example by building the foundations deep enough not to be affected by them? How can we find this out and should we even bother pursuing the purchase – or just walk away? NS

A If it makes you feel any better, the proximity of trees to the new building may be no cause for concern. According to the Royal Horticultural Society “most trees growing near buildings cause no damage” and “even where conditions mean the risk [of damage] is high, only a very small proportion of trees will go on to cause subsidence”. Indeed, the RHS seems so relaxed about the problem that it suggests you don’t really need to take action “until a tree becomes a real risk and causes damage”. The key issue isn’t necessarily the tree – or trees – but rather the soil that it is planted in.

Whether there are trees or not, subsidence is what can happen to buildings on soils, such as clay, that shrink and expand in response to their moisture content. In times of drought – typically in the summer, and made worse by the presence of thirsty tree roots – clay soils shrink, and during periods of prolonged rain they expand. This shrinkage and expansion may cause movement, which in turn can cause subsidence and cracks in the fabric of a property – normally around windows and doors. However, subsidence is likely to be a lot less of a problem if the soil in which trees are planted is relatively free-draining.

The main reason not to worry is that current building regulations mean that builders and developers have to take account of nearby trees when drawing up plans. According to the Royal Institution of Chartered Surveyors, modern buildings are seldom affected because foundations have to be sufficiently deep to counteract the potential damage caused by tree roots.

If you want to check that building work conforms to building regulations, you can check with the local planning department. You can also arrange for a survey by a tree specialist if you want to put your mind at rest. Another thing to bear in mind is that, if the neighbour’s trees did cause damage, it is the responsibility of the owner of the tree to pay the full cost of repairs. In the case of the property you are looking at, it’s likely that the neighbour’s wall will suffer before any damage is done to your potential new home.

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