According to RICS, underpinning can cost anywhere from £10,000 to £75,000 for a typical house. These figures can be even higher for larger properties.
The overall cost of the work will depend on the extent of the subsidence and subsequent damage. You may also need to consider underpinning when planning an extension or renovation.
It is a lengthy and disruptive procedure, which could see you moving out of your home while work takes place. As a result, you will need to consider extra expenses like alternative accommodation. If the work impacts adjoining neighbours, you may need a Party Wall surveyor.
Below we look at the underpinning process, the methods available and all the costs involved with underpinning a house.
What is Underpinning?
Underpinning is designed to strengthen the foundations of a property. This construction method is most commonly used on properties impacted by subsidence. Subsidence can range in severity, weakening the structure and foundations of buildings.
Underpinning adds extra support beneath a building’s foundations to prevent the property from sinking into the ground. The support can reinforce or replace foundation damage, ensuring the structural integrity of the home.
How Much Does Underpinning Cost?
On average, underpinning costs £1,500 to £2,600 per square metre, according to CheckaTrade.
Traditional mass concrete underpinning is the cheapest option, where the area is excavated and concrete is poured in. Piling is the most expensive option, costing around £2,600 per square metre. Be aware that this is just the cost of underpinning and there are other costs associated with the process.
| Type of underpinning | Cost | Pros | Cons |
|---|---|---|---|
Mass Concrete (or Pit Method) | £1,500 m2 |
|
|
Beam and Base | £2,000 m2 |
|
|
Mini-Piling | £2,600 m2 |
|
|
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Additional Costs to Consider
The cost of underpinning a property is more than the underpinning itself, with several other costs to consider. These include:
Planning permission (£624)
In the event you need planning permission, this costs £624 on average in England. You should check with your local council if planning permission is required for the work being undertaken.
Building Control Notification (Varies)
You will need to notify your local building control office before any work takes place. Fees for this vary depending on the local council.
Structural Engineer (£50-£90 an hour)
A structural engineer may need to carry out inspections and tests. They can advise you on whether underpinning is required and what method would be best. They can also help you obtain planning permission and ensure Building Regulations are adhered to. The hourly rate for a structural engineer is around £50-£90 an hour according to MyJobQuote.
Party Wall Agreement (£90 and £450 per hour)
You will likely be responsible for all the costs associated with a party wall survey and obtaining a Party Wall Agreement. The hourly rate of a Party Wall Surveyor ranges between between £90 and £450. On average party wall surveying costs are around £1,000.
Tree surgeon (£240 - £400 per day)
In the event trees and shrubbery need to be cut back or removed entirely to clear the area. The average cost is £240 - £400 per day according to Checkatrade.
Alternative accommodation (£97-£112.63 a night)
If you can't stay with friends or family, you will need to factor in the cost of a hotel or Airbnb. The cost depends on where you live, with large cities like London costing considerably more than other areas. According to Witter Towbars, the average cost of a hotel in England is £100.87, £97 in Scotland, £112.63 in Wales and £112.33 in Northern Ireland.
You should also consider the cost of any remedial work required once the underpinning is complete. For example, drainage and pipe replacement, fixing damaged walls or flooring and landscaping.
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What Factors Impact the Cost of Underpinning?
The cost of underpinning varies and will be impacted by:
The type of property
Age of the property
Size of the area being underpinned
Cause and severity of subsidence
Foundation depth
Party Walls
How much remedial work is needed after the work
The cost of underpinning varies and will be impacted by:
- The type of property
- Age of the property
- Size of the area being underpinned
- Cause and severity of subsidence
- Foundation depth
- Party Wall
- How much remedial work is needed after the work
Who Pays for Underpinning?
More than likely, the homeowner will need to pay the costs associated with underpinning. As a result, you will need to budget accordingly and look at your options to fund the project. This could include a loan or equity release.
However, there may be some instances where you can have some - if not all - of the costs covered. These include:
Home insurance policy
Check if your building insurance covers subsidence and how much they will cover you for. You should also be aware of the excess you need to pay when it comes to insurance claims.
National House-Building Council
Subsidence isn't unique to older properties. NHBC certificates cover newly built homes for structural defects and subsidence for 10 years. However, they will not pay out if you are also covered by building insurance.
Coal Authority
Claims for subsidence caused by coal mining can be dealt with through the Coal Authority. You must submit a Damage Notice Form. From here, the coal authority will likely send an engineer to inspect the damage. You will need to inform your insurance provider that you have made a claim through the Coal Authority.
Is Underpinning the Right Option for My Property?
The Institution of Structural Engineers recommends underpinning is only used as a last resort. It is estimated that fewer than 5% of properties suffering from subsidence require underpinning.
Be aware that underpinned houses are harder to insure and can lose as much as 20-25% of their value, according to Bettermove. It is therefore strongly advised that you seek the advice of a qualified surveyor before planning any work.
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Are There Alternatives?
There are alternatives to underpinning which can be used depending on the damage and extent of subsidence. The most popular is injecting resin through small holes in the ground. The resin expands as it goes, following the path of least resistance. This stabilises the ground and causes minimum disruption.
Resin injection is generally cheaper than traditional underpinning. This costs around £1,200 per square metre on average. It is considered cleaner, less disruptive and quick and efficient. However, it won’t offer the same stability as traditional methods.
Need a Surveyor?
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