With climate models forecasting hotter, drier summers that will put increased stress on soil and housing foundations, an estimated 6.64 million properties in the UK will be at medium to high risk of subsidence by 2030.
When the ground beneath a building becomes unstable, the structural integrity of the home is at risk. Underpinning provides a crucial solution for homes in need of added foundation support. But how do you know if your house needs underpinning, what does the process involve, and when is it time to call in the experts? Let’s explore.
What Is House Underpinning?
Underpinning is a method used to reinforce and strengthen the foundations of an existing building. Over time, foundations can weaken due to soil changes, poor initial construction, or additional structural loads. The process involves deepening or widening the foundation to provide better support, with various underpinning methods such as mass concrete underpinning, beam and base underpinning, or more modern techniques like resin injection. Each method addresses specific foundation issues to stabilise and protect the structure.
Why Might a House Need Underpinning?
Several reasons can lead to a house needing underpinning:
Subsidence
Subsidence occurs when the ground beneath a house shifts, causing the foundation to sink or settle unevenly. This can result in serious structural damage if not addressed. In the UK, subsidence is a growing concern, particularly in areas with clay-heavy soils that expand and contract with moisture levels. See our guide for for more information on What Causes Subsidence and How to Manage It.
The top three causes of subsidence in the UK in 2024 are:
- Root-induced clay shrinkage: 60% of cases
- Running water: 18% of cases, from leaking drains or mains water supply pipes
- Poor ground: 18% of cases, including infill and consolidation issues
Foundation Damage
Natural events such as tree root intrusion or prolonged water exposure can significantly compromise a foundation’s stability. Substandard construction methods, such as insufficient footing depth or using poor-quality materials, can also cause the foundation to fail prematurely.
Change To The Structure
Adding an additional storey or extending a property can put extra strain on existing foundations. If the current foundation is not strong enough to bear the added weight, underpinning may be necessary to ensure the house remains structurally sound.
What Signs to Look Out For
Homeowners should watch for early warning signs that may indicate foundation problems:
If you notice any of these signs, it’s important to seek professional advice as soon as possible. Early intervention can prevent further damage and reduce the cost and complexity of underpinning work. At Dart & Co., we specialise in underpinning and foundation repair, to ensure your home remains safe and stable.
How Much Does It Cost to Underpin Your House?
The cost of underpinning varies depending on several factors, including the size of your property, the underpinning method used, and the extent of the issue.
The average cost of underpinning per square metre ranges between £1,500 and £2,600. Mass concrete pouring is typically the most affordable option, averaging around £1,500 per square metre, while piling, a more complex method, can reach up to £2,600.
However, more extensive underpinning could push costs higher, particularly for larger homes or those with significant structural damage. It’s essential to consult a professional for a tailored quote.
House Underpinning Process: Step by Step
- Assessment and Inspection: A structural engineer will conduct an in-depth assessment of the foundation to determine the extent of the damage and the best underpinning method to use.
- Excavation: Trenches are dug beneath the existing foundation, allowing access to the footing. The depth of excavation will depend on the chosen method.
- Foundation Strengthening: This stage varies based on the method chosen:
- Mass concrete underpinning: Concrete is poured into the trenches to reinforce the existing foundation.
- Beam and base underpinning: Concrete beams are placed beneath the house to spread the load more evenly.
- Resin injection: A fast-curing resin is injected into the ground to stabilise soil and lift the foundation.
- Curing: Once the material is set, the foundation is left to cure and stabilise over time.
- Final Checks: A professional will conduct a final inspection to ensure that the underpinning has effectively stabilised the home.
When To Consult A Professional
If you spot any signs of subsidence or foundation issues, it’s essential to reach out to a professional structural engineer or contractor immediately. They’ll assess the problem and advise on the best course of action, whether it’s minor repairs or a full underpinning solution.
Need expert underpinning services? The experienced team at Dart & Co. will guide you through the process and ensure your home remains safe and secure. Get in touch today for a no-obligation consultation!
House Underpinning FAQs
Yes, in the UK, underpinning requires building regulations approval. This is to ensure that the work meets strict safety and structural standards. A structural engineer must assess the foundation and supervise the process to ensure compliance with the regulations. For more information on underpinning regulations, see our guide here.
Underpinning can affect a property’s value. While it can resolve structural issues, some buyers may be wary of purchasing a home that has needed underpinning. However, having a certification from a structural engineer stating that the underpinning work was done properly can reassure potential buyers.
In many cases, you can remain in your home during underpinning, especially if the work is confined to certain areas. However, there may be disruptions, such as noise and vibrations, depending on the scope of the project.
The timeframe for underpinning can vary based on the size and complexity of the project. Typically, most underpinning jobs take anywhere from a few weeks to a couple of months to complete. For an accurate timeline tailored to your property, feel free to get in touch with us at Dart & Co.
When done correctly, underpinning can resolve subsidence issues. However, if the root cause of the subsidence (like poor drainage or nearby tree roots) isn’t addressed, the problem could return.