What is ground heave? 

Ground heave is the upward movement of the soil beneath a property. This is often caused by expanding soils. When the soil absorbs moisture, it swells and pushes the foundations upwards. Heave is common in locations with clay-rich soils. This is because clay expands significantly when the soil absorbs water and rises. As a result, the upward pressure can lead to visible structural changes in the walls or floors over time.  

What causes ground heave? 

The phenomenon is often caused by a change in moisture levels in the soil. Here’s a list of some of the most common causes of ground heave: 

Clay soil expansion 

Clay soils are made up of fine particles, which absorb water fast, causing the soil to swell when wet and shrink when dry. This shrink-swell cycle makes clay-rich areas more prone to heave.  

Heavy rain 

Consistent heavy rain or flooding increases water content in the ground, especially in clay-rich soils. 

Leaky pipes or drains 

Leaks from damaged or overwhelmed drainage systems can saturate the surrounding soil, which can lead to uneven expansion beneath the building.

Tree removal 

Heave often occurs after vegetation is removed from clay soils. During heavy periods of rain, the soil begins to retain more moisture, causing it to expand. 

What are the signs of ground heave? 

The symptoms of ground heave can often look like other structural issues so identifying it early can be difficult. However, there are some key signs to look for.   

Vertical cracks, especially in walls or brickwork

Raised or uneven floors

Patios, driveways, or paths that start to lift upwards

Windows and doors that become difficult to open or close

Bulging walls or flooring

Is ground heave the same as subsidence? 

Ground heave is often confused with subsidence, however, they are two different problems. In a nutshell: 

• Ground heave is the upward movement of the ground due to soil expansion.

• Subsidence is the downward movement of the ground due to soil shrinkage or instability.

It’s important to know the difference as the causes, risks to property and solutions aren’t the same. The table below shows the key differences between ground heave and subsidence. 

How is ground heave treated?

It depends on the severity of the movement and what the underlying cause is. In most cases, getting professional help from a geotechnical specialist is required. They will assess the ground conditions and recommend the most appropriate solutions. Some of the most common solutions include: 

• Improving drainage – fixing leaks or upgrading drainage systems can help prevent soils from expanding further.

• Reinforcing foundations – in extreme cases, structural support may be needed to protect the building.

How Mainmark technologies improve ground conditions 

Mainmark offers a range of trusted methods to treat various ground-related issues, often using non-invasive techniques. An example of this is resin injection, which fills in voids and improves the density of the ground. This targeted solution addresses structural issues without the need for extensive excavation or rebuilding. 

Understanding ground heave 

In short, ground heave is a serious issue that involves the upward movement of soil, which can lead to structural damage in a property if it’s not addressed early. Recognising the signs of ground heave and knowing how it differs from subsidence can help homeowners make informed decisions about protecting their homes.  

If you spot any signs of ground movement, getting professional help is a safe course of action. Contact Mainmark UK for further advice. 

FAQs: 

Common questions about ground heave 

What is ground heave in simple terms? 

Ground heave is when the soil beneath a property expands and pushes upwards, often due to increased moisture in clay soils. This can cause floors to lift, walls to crack and foundations to move. 

What is the difference between ground heave and subsidence? 

Ground heave is the upward movement of the ground, usually caused by soil expansion, while subsidence is the downward movement caused by soil shrinkage or loss of support. The two require different approaches to treatment, so a correct diagnosis is essential.

What causes ground heave in the UK? 

Common causes of ground heave in the UK include clay soil expansion, prolonged rainfall, leaking drains or water pipes, and the removal of large trees. Clay soils are particularly prone to heave because they expand significantly when they absorb moisture. 

What are the first signs of ground heave? 

Early signs of ground heave include raised or uneven floors, vertical or widening cracks in walls, and difficulty opening or closing doors and windows. Outdoor features such as patios or driveways may also start to lift. 

Is ground heave dangerous? 

Ground heave can lead to structural damage if left untreated. While it does not always pose an immediate risk, ongoing movement can affect the stability of a property, so it is important to seek professional advice early. 

Can ground heave be fixed? 

Yes, ground heave can be managed and treated once the underlying cause is identified. Solutions may include improving drainage, managing moisture levels in the ground, or strengthening ground conditions using specialist engineering techniques. 

Is ground heave covered by insurance? 

In many cases, ground movement including heave may be covered by buildings insurance, particularly if it is linked to soil conditions or tree removal. However, cover depends on the specific policy, so it is important to check with your insurer. 

How do you stop ground heave from getting worse? 

Managing water around the property is key. Fixing leaks, improving drainage and avoiding sudden removal of large trees can help reduce the risk. If movement is already occurring, early intervention can prevent further damage. 

Who should I contact if I suspect ground heave? 

If you suspect ground heave, you should contact a specialist ground engineering company or structural expert. A professional assessment will identify the cause of movement and recommend the most appropriate solution.