Why are heatwaves a concern for property foundations? 

The risk isn’t solely because of long periods of hot, dry weather, but because they are often followed by prolonged spells of heavy rain. It’s this alternating pattern of dry and wet weather that causes the most damage to foundations. Areas dominated by clay-rich soils are especially prone to changes in moisture. When the ground dries out, clay shrinks and when it rains after a dry period, the ground quickly expands. This repeated cycle puts increasing stress on property foundations. 

What happens underground when there’s a heatwave? 

During dry periods or drought, much of the moisture in the ground is drawn out of the soil by heat and the roots of trees or large vegetation such as shrubs. These roots will then compete heavily for the moisture that remains in the ground. This moisture loss causes the soil to shrink and pull away from the foundations. In areas with clay-rich or peat soils, this shrinkage can potentially open voids, which are empty pockets beneath your foundations where the soil once sat firmly underneath.  

As a result, when it does eventually rain, some areas will absorb moisture faster than others, causing different parts of your foundation to shift at different rates (differential settlement). This is what causes much of the visual damage homeowners see, such as: 

• Diagonal cracks around doors and windows.

• Doors or windows that start sticking or become misaligned.

• Uneven floors or sloping floors.

• Gaps forming where walls meet skirting boards or the floor.

It’s important to remember that these signs don't necessarily indicate structural failure. Some fine or hairline cracks could be an indication of normal seasonal temperature changes or your home settling naturally. However, you should keep an eye on these cracks if they increase in number or expand over time.  

Is your home at risk of ground movement? 

Not all properties are at risk, however, some are more susceptible than others. Older homes with shallow foundations have a higher risk because the foundations sit directly within the active soil zone. This zone refers to the upper layer of soil where factors such as seasonal moisture fluctuations and temperature changes cause the ground to shift, expand or shrink. 

Properties near large trees are also at risk, as tree roots absorb significant amounts of moisture from the soil, causing it to shrink. Additionally, conservatories or extensions built on poorly compacted soil or homes sitting on previously disturbed ground should be monitored during prolonged dry periods.

Modern ground improvement techniques 

While ground issues are a cause for concern, if it’s addressed early, the issue can be manageable. Your first step should be to seek professional advice from a ground engineering specialist such as Mainmark who will assess your property and recommend the best repair solutions. Where movement is identified, modern ground improvement techniques can be used to strengthen and possibly re-level the ground. 

Techniques such as resin injection or computer-controlled grouting often don’t require excavation, heavy machinery and often typically there’s no need to vacate the property. These methods work by injecting either resin or grout via small holes into affected slabs or foundations. Thereby filling voids and improving the ground. Works are typically completed within days and can be targeted precisely at the area of concern rather than focusing on the whole foundation. 

If a tree is the cause of ground movement, Mainmark can provide a root barrier system, which allows the tree to stay in its place and helps restrict its roots from branching out towards your foundations in search of moisture.  

It’s important to remember that early intervention is often simpler and more cost-effective than making reactive repairs once subsidence has occurred. 

For example, a recent project at a terraced home in Dublin saw a property suffering from subsidence. The location necessitated a nimble, efficient solution. This, combined with the need to conduct repairs within a tight deadline, meant that Teretek® resin injection was the ideal solution for the project. It’s an example of how our effective solutions and quick-turnaround support ground issues triggered by surrounding factors.  

Take action early 

Heatwaves are no longer a random occurrence in Ireland, which means the ground beneath properties is increasingly at risk from potential subsidence. While not every home is at risk, it’s important to keep an eye on your property during long spells of hot weather for any early warning signs of ground-related issues. Acting early helps prevent further damage to your home and more expensive reactive repair work. Ground engineering specialists can assess the severity of the issue and often recommend modern solutions that are less disruptive and less expensive, giving you peace of mind.  

If you’ve noticed the warning signs or have any concerns about ground movement or subsidence, it’s worth getting an expert opinion sooner rather than later. Speak to Mainmark Ireland today to arrange a home assessment.