How much does underpinning cost in 2024?

Underpinning costs in 2024 vary depending on the type of underpinning method used. As a starting point, typical costs for the traditional methods of underpinning are £1,500/m2 for mass concrete, and £2,600/m2 for the piling process.

Cost for beam and base piling on average is £2,000/ m2. For the more modern alternative to underpinning, a resin injection process typical costs1 sits around £1,200/m2.

These are only average and the exact cost for the traditional underpinning of residential properties, and commercial structures, will vary depending on many factors, including the size and type of property, the width, depth and condition of the foundations, and if underpinning is required where subsidence has already occurred, the scale of that subsidence. As a rough indication, the cost of underpinning an average 3-bedroom semi-detached house will be in the region of £12,500.

As well as the costs for the underpinning process, there could be additional costs to consider. These may include hiring a structural engineer, at around £50 to £90 per hour, to carry out inspections, give guidance on the most appropriate method to use and to prepare any documents required for Building Control. Planning permission may also be required at a cost of around £462 as will the payment of a Building Control application, where fees can vary between £150 to £250. If a property has a party wall, or walls, and the neighbours don’t consent to the work being done, a party wall agreement will need to be drawn up. This could cost as much as £1,000 per neighbour.

Other factors to consider are the level of disruption that could be experienced with each method and the timescale required for the underpinning process to be completed.

As we have discovered, the costs of different methods of underpinning and alternatives vary, with resin injection and mass concrete being the most cost effective and traditional piling being the most expensive per square metre. However, not all methods are suitable for all projects. Each method will also bring with it different levels of disruption to the property whilst the work is carried out and require different timescales to complete the process.

Whilst piled underpinning comes at the highest financial cost it can cope where deep foundations are required to carry out the underpinning and transfer the foundation load deeper into the ground where more stable soils are present. Piling can cope well with a variety of ground conditions. It is carried out by skilled operatives and involves pipes being driven into the ground at regular intervals. Concrete or steel connects the pipes to give a solid foundation. Apart from the cost, underpinning by piling requires heavy machinery to be used, which can be a disruptive presence for the duration of the work.

Mass concrete is the most cost-effective traditional underpinning method and is a relatively straightforward process. However, this method can only be used at limited depths. Holes about 1 metre wide are dug under the walls to a suitable depth and at a frequency determined by an engineer. They can be dug out by hand without the need for the heavy machinery required for the piling method. The holes are boarded out, and concrete is poured in to fill the hole and strengthen the existing footings. This is done one section at a time. The concrete must be allowed to set before proceeding to the next to ensure that the property is always given maximum support through the underpinning process. This makes mass concrete a time-consuming process.

The beam and base method is similar to the mass concrete method. The main difference is that after the holes are dug beneath the foundations that need to be supported, they are filled with concrete, and a supporting metal beam is placed on top to spread the load from the building above. It offers more stability than the mass concrete method; however, this comes at a higher financial cost.

The modern resin injection alternative method of underpinning uses a very different approach to the traditional methods we have looked at so far. It uses a precise process to deliver an expanding polyurethane resin into the ground through a set of small-bore injection tubes that are typically 16mm in diameter if used around the perimeter of the building and only 6mm if the process is required inside the building. The position of the injection tubes will be tailored to the nature of the underpinning needed for each project. After being injected into the ground, the resin expands and hardens to fill any voids and strengthens the ground. Controlled injection of further resin can then be used to return the building to the required level.

Resin injection process is non-disruptive and fast, with the work on a typical house taking on average one day. However, it may only be suitable for some applications, but as the method with the lowest typical cost is worthy of consideration when looking for alternatives to the more disruptive and time-consuming traditional underpinning methods.

When exploring typical costs per square metre, alternative modern resin injection process is the most cost effective and compares well against the more traditional underpinning methods. There are many factors to consider before the overall cost of an underpinning a project can be established. The impact and longevity of the method itself on the level and duration of disruption that can be expected will also play an important part in the decision-making process.

It is important to remember that not all methods we have discussed are suitable for all buildings requiring underpinning. Advice should always be sought from suitably qualified engineers before deciding the best underpinning or alternative method for your building.

There is no doubt that modern resin injection can offer a fast and less disruptive alternative to traditional systems and should be explored as a viable and cost effective alternative that can significantly reduce the amount you would have part with when using traditional underpinning costs in 2024.

Mainmark’s Teretek® resin injection solution is a non-invasive and environmentally inert way to deliver both ground improvement and re-levelling of residential properties and buildings across the industrial, marine and commercial sectors. It offers a fast, economic and overall cleaner alternative to traditional underpinning and comes with a 20-year product warranty.

If you would like to learn more about modern resin injection systems as an alternative to traditional underpinning methods, please check out our page on underpinning contractors, where you will find a wealth of helpful information. If you have a particular underpinning issue, please contact us for an expert view on how we can help support your project and building.