Do trees cause subsidence?
We are often consulted or called in to look at homes or buildings that are showing cracks or have issues that are suspected to be caused by the location of trees, whether the property owners or the Neighbours. Trees are a contentious issue and are usually blamed for issues with drainage, cracks or subsidence. But it is not always the case that it is the tree’s fault and that is why it is important to seek the professional advice of a structural engineer before ripping out the tress – as this could cause further problems.
Problems with foundations could be caused by several things, including not being laid correctly in the first place. Foundations need to take the soil conditions into account. If they were built on variable ground where there isn’t a consistent stratum. Solution features, where surface water has dissolved the underlying chalk, could be the cause of any movement especially. High-risk areas are often near where there is a cover of clay strata such as North Kent, Sussex, Hampshire, Dorset, Buckinghamshire, Hertfordshire and East Anglia.
It is important to rule out any alternative causes before looking to the trees.
Trees can cause problems for foundations if their proximity and growth are not accounted for at the time of foundation design. If you have a house built on clay or shrinkable soil and you have a tree nearby that is taking the moisture from the soil, the soil will become desiccated. If the foundations are not deep enough there will be movement causing subsidence and cracks in the building.
If you remove the tree the ground will eventually recover and potentially move back to its previous position but there is a risk that if you cut the tree down the rehydrated ground will push the foundations up creating further issues.
The best option is to underpin the house before you cut down the tree. Once the ground has recovered then any repairs can be completed.
If you see that you have the beginnings of a crack or notice the building sinking it is worth consulting a structural engineer. They will be able to find the problem, maybe with a trial pit to examine the foundations and propose a solution.
You can call us today on 01993 2250825 if you have concerns about your or your neighbour’s trees and any movement in your property and we will talk you through how we can help.