Why autumn rain can affect ground conditions beneath your property

Clay and granular soils are more vulnerable to changes in moisture levels. During hot, dry weather, clays can lose moisture and shrink. As the soil loses its volume, it can shift unevenly, potentially leading to movement beneath the foundations.

When the wet weather returns, clay soils can absorb water and swell. This can increase pressure on the surrounding ground, especially if the soil has significantly shrunk following a prolonged drought. Flooding can be caused by dehydrated clay soils as it takes a number of weeks for the clays to start to absorb the water. Initially, the water will run off the soil, creating flash flooding. This repeated shrink-swell cycle driven by changing weather patterns can put stress on buildings throughout the year.

Granular soil types, such as sand and silt, are more affected by heavy rain and flooding because they allow water to rush through, which washes away the fine particles, leading to erosion and creating voids. This then causes a property’s foundations to move into said void.

What signs should homeowners watch for during autumn?

As we move into the autumn months and the rainy days return, it's important to check for any changes on your property, especially if you've noticed cracks or other issues during the summer. Some signs to look for include:

• Existing cracks that have increased in number or have become wider and longer.

• New cracks forming around doors or windows.

• Sloping or uneven flooring.

• Doors or windows that have become difficult to open or close.

• Any changes to current cracks following heavy rain.

• Gaps around wall junctions and skirting boards.

Although cracks can be an indicator of ground movement, not all cracks are the same. Fine-line or hairline cracks are usually cosmetic and result from seasonal temperature changes, whereas any cracks that increase in size or appear around openings should be monitored.

How is ground swelling addressed?

In some cases, ground swelling can be more complex to manage than soil shrinkage. This is because the best approach depends on:

• The cause of movement

• Type of soil

• How the foundations are behaving

If structural movement is already occurring, more extensive repairs may be needed. A thorough ground assessment will uncover the extent of the issue, the underlying cause and Mainmark will recommend the best remediation works. Depending on the cause and severity of the movement, works could include underpinning, soil strengthening or other ground improvement techniques.

It’s important to address the underlying cause, rather than just treating the visible symptoms alone. Understanding the subsoil conditions and variations in moisture levels in relation to the property foundations helps to identify the most appropriate solution.

What can you do to prepare during the autumn months?

Addressing ground-related issues early can help prevent any further damage so, it’s important homeowners keep an eye out for any signs of potential movement.  

You should monitor existing cracks. Keep a record and take photos of any changes in size or appearance.

Also check the drainage and gutters on your property. Leaking or damaged drains can significantly impact ground moisture levels, and if escaping water reaches your foundations, this can cause further problems.

The key thing to remember is not to ignore any progressive changes. If cracks are worsening or are accompanied by sticking doors or other signs of movement, you should immediately seek professional advice.

Climate patterns are becoming increasingly variable in the UK so, understanding how the ground behaves during periods of drought and extreme wet weather will help homeowners prepare for potential issues. Identifying the underlying cause of ground movement is the first step to finding the most appropriate remediation work. Mainmark can help homeowners understand what’s happening beneath their property and recommend the best solutions.

If you've noticed cracks, sticking doors, uneven floors or other signs of movement, it's important to seek professional advice early. Mainmark Ground Engineering can assess the cause of the issue and recommend the most appropriate remediation solution. Book an in-person site assessment today to speak to an expert.