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What is subsidence?

Subsidence is the gradual downward movement of the ground beneath a building, causing the foundations of the building to become unstable and the property begins to sink down as a result

Subsidence affects tens of thousands of UK residents every year, devaluing their property and compromising its structural safety. It also impacts warehouses, factories and other commercial and industrial buildings. Highways, roads, airport runways, sea walls and harbours and other infrastructure can be critically impacted by subsidence.

Generally, subsidence is not an overnight occurrence, it can take many years for it to show any effects on structures. The visible signs at the start are usually small and some property owners may believe it’s something that can be addressed later. Unfortunately, this is never the best option. Subsidence is best dealt with as early as possible to minimise the work that must be carried out during the repairs.

Ignoring subsidence can have a wide variety of knock-on effects depending on what you use your property for. Landlords may struggle to rent out a property that has subsidence, as tenants want to feel secure in the home that they live in. People looking to sell their house will struggle to sell a house that has subsidence for the same reasons.

If you’re looking to continue living in the property, subsidence can also cause serious structural damage in the long term, and in the worst cases, can cause complete collapse of the property.


How To Fix Subsidence?

Historically, one of the few options for fixing subsidence was concrete underpinning. This was a costly, timely and messy procedure that included excavating the ground beneath your property and supporting the foundations with large volumes of concrete. Anyone living in the property at the time would have to move out, which could put families without a home for an extended amount of time, or a landlord without rental income.

Luckily, modern technology enables us to fix subsidence much more efficiently and much more cost effectively. Modern resin injection methods can be used to successfully strengthen the ground and re-level and repair homes affected by subsidence in significantly less time than it takes for traditional concrete underpinning. In the majority of cases, the occupants don’t need to move out!

Mainmark’s Teretek® resin injection solution is a proven, cost-effective and quick alternative to more invasive methods. Using a process similar to keyhole surgery, the work can often be completed in one day.  It is widely used to strengthen foundation ground, re-level buildings and remediate issues in residential, commercial, industrial, mining and infrastructure projects.

Subsidence signs

What are the signs of subsidence?

Cracks in walls

he most common sign of subsidence is cracks appearing in internal and external walls. Cracks are a mechanism for releasing stress in a structure, which naturally weakens your property’s design.

It’s important to note that not all cracks mean that your house is suffering from subsidence, small cracks are often just cosmetic and could purely be down to the age of the property. When assessing the cracks in your walls, it’s important to look at the following:

  • Are two sides of the wall at differing heights?
  • Is the crack wider than 5mm, or can you insert your little finger?
  • Does the crack follow a zig zag or stepped pattern?

If you have cracks in your walls and answered yes to any of the above, then you may have subsidence.

Cracks in walls

Jammed doors and sticking windows

Subsidence cracks commonly appear near doors and windows, as these are weaker points in the structure of the home and therefore more prone to cracking. The cracks can affect doors and windows differently depending on where they appear. Some may cause gaps to appear around their frames and for the door or window to swing open by itself, whereas some may cause the doors and windows to become stuck, jammed and difficult to open / close.

Jammed doors and windows

Sinking floors

Sinking floors are often the most obvious signs of subsidence, but it’s still important to keep your eye out as it’s best to catch it as early as possible!

Sinking floors can form in different ways, if the subsidence is concentrated in the middle of the property, then the centre of the floor can indent or “dish”. Here you should look for the floorboards pulling away from the skirting boards primarily in the middle of the wall.

Sinking floors can also happen on one side or corner of the property, caused by the ground sloping a certain way. Again, the best way to visibly notice this is to see the floor pulling away from the skirting boards at a specific side or corner of the room.

Sinking floors

How does subsidence affect house sales?

For many, purchasing a property is the biggest investment of their life. The buyer and the seller will want a smooth process, however, there will often be a need for compromise.

For sellers, the final sale price is typically the biggest compromise, while buyers usually need to be flexible regarding the location, layout and size. However, expensive structural repairs may be a deal breaker for many house hunters.

If you’re buying a house and you suspect that it has subsidence, then you should have a full building survey done, this should inform you if there is any risk of subsidence. If subsidence repair work has taken place in the past, then you should obtain documents from the seller to verify that repairs were done to the standard set out by the Building Research Establishment. These documents should include:

  • A formal completion certificate (issued by the council).
  • A certificate of structural adequacy.

There may be some guarantees within these repair documents that you will want passed on to you. It’s also a good idea to find out more about the insurance for the property, as properties with a history of subsidence may have limited or more expensive policies.

If you’re selling a house that has subsidence or has a history of subsidence, transparency is key. You may also have to be prepared to lower your asking price; a 2021 report by SOLD.co.uk found that houses affected by subsidence saw a valuation decrease of 20% – 25%.

Sellers should remember that having subsidence on a property does not mean that it can never be sold! Your property will have many positives that you should look to promote and if the work has been completed to the appropriate standard, it is only a matter of time until a buyer is found.

Mainmark subsidence remediation technologies

Teretek® – Subsidence remediation with resin injection

Teretek® resin injection technology can be used to provide ground improvement beneath existing structures and help treat subsidence. We drill small holes through the ground-bearing slabs or the foundations into the deteriorated soil strata underneath. These holes are then used for injecting our specialist resin formula, filling cracks and voids, stabilising the ground and restoring the structure to its correct level.

JOG – Subsidence remediation with computer-controlled grouting

JOG computer controlled grouting uses a high-mobility cementitious mix. This mix is pumped into multiple injection depths during a meticulously monitored process that deploys laser sensors and computers. This is a precise method for treatment of subsidence, improving and consolidating weak ground that delivers specific, engineered ground improvement outcomes, regardless how complex the project is.

Terefil® – Subsidence remediation with cementitous fill

In areas with challenging ground conditions, Terefil® replaces the existing soil with a raft of engineered lightweight cellular concrete. Our permeation and jet grouting techniques solidify soil, increasing load-bearing capacity and helping with subsidence. Suitable for a range of geotechnical settings, the structural filler is a specialist material ideal where other filling solutions are too heavy, for sites with restricted and limited timelines projects.

Why Choose Mainmark?

Delivering exceptional outcomes to our
clients, partners and team


Our world-leading ground engineering technologies achieve safe, accurate and economically delivered outcomes. We understand that ground engineering can be complex and no single method suits every project. We work with our clients and partners to recommend the right solution for each challenge.


Mainmark ground improvement solutions have been proven for over 30 years. Our ground engineering specialists have worked on over 30,000 projects worldwide, from straightforward residential subsidence to post-earthquake remediation in Japan and New Zealand. We aim to be the best at solving your ground problems with minimal disruption.


Our experienced team has a wealth of knowledge in residential, commercial and industrial buildings, as well as highways, rail, utilities and infrastructure. Our ground engineers can raise and re-level buildings, providing support and improving ground performance.


The combination of our proven ground improvement technologies and our experienced ground engineers enables us to re-level and re-support buildings affected by subsidence across various sectors.


Our problem-solving approach and recommendation of ground engineering solutions sets us apart from the competition. The complexity of ground improvement requires a range of state-of-the-art technologies to meet both project and client requirements.


We are trusted to present effective and creative solutions to many types of ground engineering problems in a wide range of sectors, including residential, industrial, commercial, civil engineering and infrastructure.

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