In the world of tree root subsidence it is the volume changes of the soil underneath a property foundations which can cause an issue.
Where tree roots encroach under the foundations of a property built on a shrinkable soil, suspectable to volume change. In the winter months when weather is wetter and water demand from trees is lower the soil swells in volume. In the summer months when the weather is hotter and drier and trees are extracting moisture from the soils to grow, the soil dries and shrinks in volume.
So in winter the volume of the soil is larger and in the summer the volume is lower.
This change in volume has been illustrated perfectly by Timothy Farewell in his soil volume video which I will link in the comments. This shows the impact that introducing and removing water from shrinkable clay soils does to its volume.
Where a property is built on a soil which is undergoing these changes in volume with the seasons, if the extent of that volume change is significant enough, the property might crack at areas of structural weakness such as window and door frames.
A sign that a property has suffered from crack damage as a result of vegetation induced soil volume change is the time of year that damage is noticed. Following a hot, dry summer, the impacts of this volume change can start to be seen in late July. This can last through the summer and reach a peak in terms of claims notification in late summer, early autumn.
So if soil volume change can be an issue and can cause properties to crack, what’s the solution?
Well the primary cause of this vegetation induced subsidence is differential movement between property foundations. What that means is that this volume change to the subsoil is an issue where a property has foundations at different depths across different parts of the building. This means that an area of a building on deeper foundations is more stable than an area built on shallower foundations.
This means that additions such as extensions, porches, conservatories and the like can be areas prone to damage. The easy answer is to effectively take into account the presence of trees when building these additional structures and ensure foundations depths are equal across the footprint of the building. Then perhaps the building can be more resilient to the volume change underground and remain stable even in the face of a hot summer.
Deeper foundations will be more costly but could perhaps save more money in the long run.
Check out how we can help with subsidence claims – Tree Root Subsidence | Tree Law – Legal tree expert
Check out a news piece about subsidence claims on Tree Law TV – The Sun newspaper reports on the heatwave of 2022 causing an increase in tree root subsidence claims
