What affects the cost of underpinning?

The average cost of underpinning is based on per square or linear metre and ranges between £1,500-£2,600. However, the exact cost of underpinning is dependant on several factors such as:

• Size and layout of the property

• Extent of foundation settlement

• Underpinning method

• Ground conditions

• Access to the site

• Depth and current condition of existing foundations

• Associated costs, e.g. surveying, planning or remedial work

A site survey can help determine the actual cost of underpinning your property.

Underpinning methods and how their cost compares

Costs vary between different underpinning methods as each one requires different equipment and installation work. Some may require more extensive excavation compared to others.

Traditional underpinning

Traditional underpinning typically involves excavating the ground beneath the existing foundations and pouring concrete to reinforce the structure above. This method can take weeks and is labour intensive. Contractors may also need significant access, which can also raise the overall cost. Average costs range between £1,000 and £2,500 per linear metre for the work.

Screw pile underpinning

Screw piling is a technique that involves mechanically screwing helical plates into the ground beneath or alongside an affected foundation. It’s a more targeted approach that requires less excavation work and the piles themselves can immediately carry the load of the foundation once installation is complete. Average costs for screw pile underpinning generally ranges between £2,000 and £4,000 per linear metre.

Resin injection underpinning

Resin injection is another non-invasive technique that involves injecting expanding resin through a set of small-bore injection tubes into targeted areas of the ground. It’s less disruptive than traditional underpinning methods and more cost-effective. Average costs for resin injection work typically ranges between £400 and £1,200 per square metre.

Does property size affect the price of underpinning?

Property size can directly affect the price of underpinning as larger buildings have a larger footprint. That means they require more materials and labour. However, it’s worth noting that it’s rare for the entire foundation to need underpinning. Underpinning is typically priced per linear or square metre for the affected area, so, you have a large property, but only a small section of the foundation may need repair, which will cost less.

How do ground conditions influence the cost of underpinning?

The ground conditions beneath the property plays a key role in determining the appropriate solution and cost. Different soil and ground conditions can behave in different ways. Subsidence or settlement may be the result of weak or variable ground, changes in moisture conditions or other issues such as made ground.

That’s why investigating the underlying cause of foundation movement is essential. Attempting to address the issue without understanding what’s causing the movement may result in settlement becoming a regular occurrence.

Site access and its impact on the price

The cost of underpinning can also be affected by how easy the site is to access. Sites with restricted access such as properties with narrow side passages or extensions may make it more difficult to reach the affected area or bring equipment to site. A site survey can help determine how much preparation is needed and what equipment is required.

Hidden costs to factor in: Survey, planning, redecoration

When looking at underpinning costs, it’s important to look beyond just the price of the underpinning work. Associated costs from professional fees, reinstatement works and having to work around utilities can add thousands of pounds to the initial estimate. These costs should be considered as part of the budget.

How to get an accurate underpinning quote

Every property is different, so, the best way to get an accurate quote is to hire a structural engineer who will initially conduct a site investigation and then determine the best approach. Without this level of detail, you run the risk of not only receiving an inaccurate estimate but a solution that’s not suitable for your foundations.

One thing for homeowners to note is that the choice of contractor should not be based on cost alone. You should check what work is being covered in the quote and if it will address the underlying cause.

How Mainmark can help

Not all foundation movement is the same. That’s why at Mainmark, our approach is to thoroughly investigate the ground conditions of each property before recommending the best repair method or underpinning solution. Depending on the cause and site requirements, we can implement non-invasive techniques such as screw pile underpinning and resin injection to strengthen the ground and re-level the structure if necessary.

Understanding the underlying cause of movement and what the circumstances are of the individual property, is the first step in determining the cost of underpinning. whether you’re concerned about ground movement or if your house needs underpinning, contact Mainmark today.