Soil Shrinkage, what is it?

What springs to mind when you hear the term soil shrinkage? It conjures up the image of gaping cracks stretching across the baked earth as the ground dries out, but it’s more than that.

Soil shrinkage occurs where the volume of moisture content within the soil changes and is most commonly found where the soil is rich in clay. Budding gardeners may appreciate clay soil for the incredibly nutrient-rich environment it creates, but the heavily moisture-retentive substance can be susceptible to swelling and shrinkage.

Why is this an issue?

Soil shrinkage is one of the greatest contributors for subsidence issues to properties in the UK.

Shrinkage can cause significant damage to structures such as buildings or walls, and while many newer built structures are often purpose built with this in mind (designed with deep enough foundations to remain unaffected), the majority of the UK’s housing stock is older and therefore will not have the same measures in place to mitigate against the effects of soil shrinkage.

Buildings with shallower foundations, typically older buildings, are more likely to be affected. The effects of soil shrinkage may present as small developing cracks which may open or close throughout the year dependant on the level of ground moisture content.

Hot weather

Hot weather is a huge contributor of soil shrinkage subsidence issues. During particularly dry summers there are typically an increased number of cases of soil shrinkage causing building damage – especially in those clay rich areas!

This is a growing concern as climate change continues to drive longer and hotter periods of extreme weather in the UK with record breaking temperatures being reached in the last few years (although we seem to have escaped the scorching temperatures this summer).

Trees are also often at the root of the issue

Heavy vegetation, trees, and dense foliage are often also at the core of the problem for soil shrinkage when their root systems grow too large.

Trees in particular can be a danger to the foundations of a property when they are planted too close. Not only can damage ensue directly through the growth of tree roots, but the roots can cause additional erosion when they absorb the ground water from soil beneath a building’s foundations causing a shift or movement to the structure.

However, cutting down trees surrounding the property is not necessarily the solution. Without the tree’s roots to absorb excess water the ground can become saturated or waterlogged, creating heave or upward movement and giving rise to its own slew of structural problems.

What are some signs of soil shrinkage?

Where soil shrinks, it leaves gaps between the soil and the buildings foundations. Overtime the foundations will settle into the spaces left behind which can lead to cracks forming and an uneven foundation.

Some signs that may indicate that you are experiencing soil shrinkage around your home are:

  • Soil pulling away from your foundation or cellar walls
  • Cracks in the foundation
  • Cracks developing along the wall
  • Sticking doors or windows
  • Uneven floors
  • Wall and ceiling lines are no longer straight.

 

If you are concerned about any cracks or potential soil shrinkage, we recommend seeking specialist advise from a qualified engineer to assist in reviewing the situation and advising on what next steps to take.

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