Does your home require underpinning? Whether you know this to be true or you’re unsure, it’s important that a structural engineer confirms this as soon as possible as underpinning is generally needed to ensure the structural security of your home and therefore the safety of everyone inside.
But what is underpinning exactly? The process of underpinning a house involves work designed to strengthen existing foundations or reinforcing them. This is often requested if the original foundation lacks the strength or stability required.
Therefore, underpinning can prove especially important for safety purposes as well as maintaining the general structure of the property. In this guide, we’ll discuss the average cost of underpinning a house and explore other related topics such as cost-affecting factors and the potential for cost overruns. Let’s dive in!
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Factors Affecting Cost
Before we look at the average cost of underpinning a house in the UK (skip to the next section if you’d like to get right to it), it’s worth looking at the various cost-affecting factors that may apply. After all, the total price will generally vary on a case-by-case basis.
Type of Underpinning Method
Firstly, there are many types of underpinning methods. One or more methods may be appropriate in the case of your home, or it may come down to a matter of preference.
Common methods, with their average costs, include mass concrete underpinning (approx. £1,000 to £2,000 per square metre), beam and base underpinning (approx. £1,500 to £2,500 per square metre), and mini-piled underpinning (approx. £2,100 to £3,000). Another choice known as expanding resin injectors costs around £700 to £1,700 per square metre.
Of course, these are approximations. Prices can vary depending on the specifics involved and other key factors.
Size and Structure of the Property
Naturally, the larger the property or/and those with more complex structures, the costlier the underpinning project is likely to be.
For example, underpinning a wall in a detached house will probably cost around 50-60% more than the same job for a semi-detached house. The cost for a professional/team of professionals to install underpinning will of course generally differ if your property’s structure makes the work more challenging.
Geographical Location
Beyond that, where you live also matters. This is because labour prices differ throughout the UK. On the one hand, labour costs in the southeast of England are usually above average, with London known for being especially expensive.
However, in contrast, labour prices tend to be below the UK average in northern England, Scotland and Northern Ireland.
Conditions of the Soil
The type and conditions of your soil may also impact the cost, both in terms of what type(s) of underpinning method and how complex the work proves to be. Both of these aspects can affect the total cost of underpinning a house.
Access and Site Constraints
If the underpinning contractors you’ve hired have difficulties with accessing the work area or/and face other site constraints, the work will likely take longer, thus probably resulting in higher labour costs.
Additional Works
If more work is needed, then underpinning a house may cost more. Additional work may include jobs related to drainage, waterproofing or performing structural repairs.
If additional work of this nature is needed it may end up costing somewhere in the region of £100s to £1,000s, but this can vary substantially depending on the exact type of additional work needed and the extent and quality of work involved. In some rare cases, the work may even cost more than £10,000 but more than likely this won’t apply.
Average Cost Range
So, how much does underpinning cost in general? We’ll now look at the average cost range for different types of underpinning house projects. This will give you an idea of roughly how much the work may cost.
Total Average Prices
Here are the average costs (i.e. labour and supply only costs combined) of different types of house underpinning projects:
- Underpinning one wall in a terrace house - £5,000 to £11,000
- Underpinning one wall in a semi-detached house - £13,000 to £24,000
- Underpinning one wall in a detached house - £17,000 to £37,000
Labour Costs
You’ll need to hire a structural engineer to determine the extent and type of underpinning needed. You’ll then need to hire a structural engineer (presumably the same one) to perform the underpinning work.
The cost to hire a structural engineer is about £80 to £120 per hour, meaning that they’ll charge at least several hundred pounds a day.
Considering the work will likely take 2-4 weeks in total, the price of labour will probably end up being more than £10,000 and a substantial fraction of the total cost, although exceptions exist. For instance, underpinning one wall in a terrace house will often come with a labour cost less than £10,000, though this can depend on the type of the type of underpinning method being used.
Materials
Along with the price of labour, the cost of materials will also play a significant role in determining the cost of underpinning a house. In general, these prices will end up around several thousand pounds.
Mini-tiling tends to feature the highest supply only costs (among popular underpinning methods), followed by beam and base underpinning, which in itself is around 33% costlier than mass concrete. Expanding resin injectors tend to be the cheapest.
Of course, the cost of materials may also vary based on the brand and quality of the materials used for the project.
Additional Expenses
While we’ve touched on additional work that may be needed (which is a type of added expense in its own right), it’s also worth noting the additional expenses that may apply even if other work is not needed.
| Type of Additional Expense | Average Price |
|---|---|
| Planning Permissions | £200 to £462 |
| Professional Fees* | £500 to £1,000 |
| Potential Accommodation Costs** | £1,400 to £5,600 |
| Building Control Fees | £100 to £300 |
* Professional fees may apply as part of hiring a structural engineer, including when additional work may be needed.
** You may need separate accommodation during the underpinning work (which usually takes several weeks) if your property isn’t habitable through this project. While this may cost thousands of pounds, you could keep costs down if family members are okay with providing you and any other members of your household accommodation for several weeks.
Planning permission will likely not prove necessary. That said, those living in a listed building or a home within a designated area (e.g. national park) may require approval.
Since planning approval can take up to eight weeks, it’s important that you discuss this with the structural engineer you hire. After all, you’ll need to have the process sped up if underpinning your house is needed as soon as possible or otherwise your home will be unsafe to live in.
So, if planning permission is required, you’ll want to ensure you approach it in the ways needed to get approval or otherwise find ways to move forward when safety is a concern.
Potential for Cost Overruns
Of course, it’s also possible that cost overruns may apply for an underpinning project. Here are some notable examples and how to mitigate these risks.
Design Alterations
Firstly, you may decide to opt for a different design or approach before the project gets underway (once approved and verified as safe and suitable by a structural engineer).
The downside of this is that you may end up spending more time and money as a result of a potentially prolonged project. Therefore, it’s important that you spend sufficient time discussing your project options and the most suitable one to avoid making U-turns later.
Conflict With Neighbours
If a party wall agreement is required (due to concerns raised by a neighbour when they have legal grounds to challenge your proposed underpinning project), this can add several hundred pounds to more than £1,000 to your total.
To help reduce the risk of this issue arising, you should ask the structural engineer you hire whether or not a conflict with a neighbour could arise. If they determine that this is possible, you should chat with your neighbour to check whether they are okay with your project.
Work Takes Long Than Expected
Of course, if it takes longer than anticipated to underpin a house (e.g. due to access issues or other repair work being needed), this can add to your total bill too. Having an idea of what sort of additional expenses may apply (and when you will need to pay these fees and when fees may not be applicable) can help you prepare for unexpected costs.
Cost Comparison with Alternative Solutions
Note: If considering an alternative option, you still need to make absolutely sure (per the advice of a professional structural engineer) that any given solution is suited to your home and the sort of the work required.
While we’ve mentioned resin injectors earlier, they may also be considered an alternative solution.
This approach is relatively cheaper, with a price of around £700 to £1,700 per square metre (or approximately half to a quarter the cost of more commonplace underpinning solutions).
Beyond that, in some cases subsidence repair may be suitable, particularly if the damage is minimal and can be fixed to ensure safety without going to the lengths of underpinning. While this work will likely cost several thousand pounds, it will generally cost less. Of course, in many cases, subsidence repair alone will not be sufficient, and underpinning will be required.
Foundation repair and replacement in general may also be suitable options. In either of these cases, the work may cost less overall than underpinning a house. However, this will still depend on the type of work involved.
Long-Term Cost Benefits
While the most important reason for underpinning a house is to ensure the safety of its occupants, there are potentially long-term cost benefits to this work too.
For one, underpinning a house when needed can reduce the risk of structural issues (both big and small) arising in the future. These issues may prove not only dangerous but costly, necessitating that your home be underpinned, and the structural damage be addressed directly.
Further, underpinning a house has the potential to increase the value of your property or at least prevent structural concerns reducing the value of your home. Ultimately, underpinning a house could save or earn you thousands of pounds or more down the line.
Conclusion
Ultimately, underpinning a house will likely cost somewhere in the region of £5,000 to £40,000 depending on key factors like the size of your home, the extent of work required, and even the price of labour in your area.
It’s important to secure a tailored quote from a suitable professional or company based on specific property and project needs. Moreover, landing several quotes is a great way to compare a range of options before deciding who you’d rather hire, such as due to their levels of experience or online reviews/ratings (if applicable).
Along with securing several quotes (before deciding who to hire), you’ll also want to ensure that you know what to expect and have an idea of the total cost, as well as checking whether or not any additional costs may apply.
Sources
https://www.ros.hw.ac.uk/handle/10399/4548
https://www.researchgate.net/figure/Main-causes-of-cost-overruns-in-UK-construction-projects_tbl1_326770313
https://www.planningportal.co.uk/permission/common-projects/underpinning/planning-permission