Why the Type of Ground Movement Matters
The thing we see over and over again on property inspections is three very different types of movement all being referred to as “subsidence”. It makes conversations pretty confusing and can lead to the wrong repair being recommended. The thing is, settlement, subsidence and ground heave are not the same thing, and knowing exactly what you’re dealing with is pretty crucial.
When we visit a property, we’re not just looking at cracks for the sake of it – we’re trying to get to the bottom of how the building and ground are interacting with each other. The technical terms aren’t there to make things complicated; they’re there to make sure we get to the root of the problem and fix it properly.
What Is Settlement?
Settlement is what we normally see in relatively new buildings or extensions as they “bed in” over time. The weight of the building is compressing the soil slightly, and then some minor cracks can appear. This usually happens within the first decade after construction has finished, or after some significant work has been done.
Typical causes of settlement in new builds and extensions
Common triggers for settlement include new loads being placed on ground that’s recently been disturbed, shallow fill that takes a while to compact, or changes to the structural layout that weren’t fully accounted for.
Common signs of settlement cracks
We tend to see finer cracking near the junctions between new and existing structures, or around openings. These cracks can sort themselves out once the ground has adjusted to the new loading.
When settlement is usually not a problem
In a lot of cases, once the initial movement has taken place, things tend to settle down. We’ve inspected loads of properties where light settlement cracking has been monitored and then sorted cosmetically without any further issues. The key is that the cracks stop changing. In some cases though we recommend that resin injection is used to help stabilise the settlement, particularly where there is evidence of softer bands of material in the ground below the foundations.
What Is Subsidence?
Subsidence is when the ground supporting the foundations is sinking downwards. Unlike simple settlement, it tends to be a progressive issue if the cause isn’t addressed.
How subsidence differs from simple settlement
Subsidence isn’t just “more settlement”. It’s driven by a continuing issue – like shrinking clay, or water washing away the supporting soil, or impact from trees – that causes the ground to lose strength or volume over time.
Common causes of subsidence in UK properties
We see a lot of:
- Shrinkable clay in dry spells, often worsened by trees and shrubs.
- Leaking drains that are softening or washing away the supporting soil.
- Altered drainage or ground levels changing how water moves around the property.
Typical signs of active subsidence
We look for tapered cracks that are wider at the top than the bottom, doors and windows that suddenly start sticking, sloping floors and signs that one area of the house is moving differently from another. The pattern and rate of change are more important than a single crack on its own.
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What Is Ground Heave?
Ground heave is the movement that catches people out because it goes in the opposite direction to subsidence – the ground rises, pushing the foundation and structure up.
How ground heave affects foundations
When soil beneath part of a foundation swells and lifts, it can crack walls, distort floors and cause doors and windows to misalign. It usually happens unevenly, so one part of the building lifts more than another.
Clay soils, water, and tree removal
In clay areas of Wales, Yorkshire and parts of the Midlands, heave can occur when clay absorbs moisture – sometimes after a big tree has been removed and the soil recovers water it previously lost. It can also be linked to changes in drainage and waterlogging.
Signs you may be dealing with heave, not subsidence
We sometimes see floors lifting away from skirting boards, cracks associated with upward movement, and areas that appear slightly higher than before. It’s easy to get this one wrong if you only think in terms of “sinking”, which is why a site inspection is vital.
How Engineers Work Out What’s Moving Your Home
Rather than just guessing from one photo, we treat diagnosis like a proper detective process.
Visual inspection and crack patterns
We study the crack location, orientation, width and whether they are tapered. We also consider how they relate to structural features like openings, corners and changes in construction.
Soil, drainage and tree investigations
We often recommend soil investigations, CCTV drainage surveys and assessments of trees or large shrubs near the property. These all help us understand how the ground may be changing beneath the foundations.
Monitoring movement over time
On some properties, we monitor crack widths or levels over a period to confirm whether movement is active and in which direction it’s going. This can be invaluable for distinguishing between settlement, subsidence and heave.
Making Sense of Movement in Building Repairs
Now that we know what we are up against, we can start having a real conversation about what our options are.
Typical Approaches for When the Ground has Settled
If the building has already settled and is stable, it’s often just a matter of watching things and making any necessary fixes internally and externally. We only get more serious if the movement is still going on or if it’s starting to affect the building’s structure.
Repair Options for Subsidence
With subsidence, we look at everything from sorting out the root cause (getting the drains fixed, managing the trees) right through to taking steps to improve the ground conditions, injecting resin, or underpinning the building. What we do will depend on how bad it is, what the soil is like and which bit of the building is affected.
Managing Ground Heave and Problems with Moisture
When we are dealing with heave, it usually comes down to finding ways to calm down the moisture levels, getting the drainage sorted, and in some cases, giving the building some room to breathe and move. Simply “gluing it down” and hoping for the best isn’t always the answer
Costs, Insurance and What to Do Next
How Movement Type Affects Repair Costs
Stable settlement can be pretty cheap to deal with. But active subsidence or heave – especially when you are talking about underpinning or piling – can be a lot more involved and expensive. Knowing what is going on early on helps to avoid any nasty surprises later down the line.
When to Get in Touch with Your Insurance or Mortgage Provider
If you think you have got subsidence or heave – or if the cracks are getting bigger and more serious – it’s usually a good idea to get in touch with your insurer sooner rather than later. They may need a report from an engineer, or some monitoring data.
Getting a Fix on Costs and an Engineer’s View
If you want a rough idea of what it will cost to fix a subsidence problem in the UK, then our repair cost calculator might be a good place to start.
For those who want one of our engineers to take a look at their property, contact us today to arrange a site visit.
Frequently Asked Questions on Subsidence, Settlement and Ground Heave
How do I tell if my cracks are just settlement or actual subsidence?
That’s the thing – you can’t get a good idea from just one photo alone. We take a closer look at the pattern, where the cracks are, how long they have been there, and whether they are still changing before we come to a conclusion.
What’s the main difference between subsidence and settlement?
Settlement is usually just a one-off thing, where the building is just “bedding in” to the ground. Subsidence is when the building is going down due to a problem that isn’t going away.
Can heave look just like subsidence?
Yes, both can cause cracks and all sorts of problems. What actually gives them away is the direction and cause of the movement – which is why we have to do some proper investigation.
Are all hairline cracks a sign of movement?
Not at all – lots of the time they are just shrinkage or a bit of thermal movement. We are more worried about the big cracks that are getting worse.
Do I always have to get underpinning if I have subsidence?
No way – some cases can be fixed just by dealing with the problem, doing some monitoring and more targeted structural fixes. We will only recommend resin underpinning if it is required!
How do engineers figure out what is causing all the movement?
It’s a combination of looking at the building, listening to its history, doing some investigations into things like the soil and the drains, and sometimes keeping an eye on things over time.
Should I be worried about any cracks in a new-build?
Not always – some cracks in new-builds are just fine. But if they are getting bigger or don’t seem to be going away, then it’s definitely worth getting a second opinion.
Will subsidence or heave affect my house insurance?
Yeah, it probably will. Insurers want a clear diagnosis and a proper plan for fixing things. Getting in touch with them early on helps to avoid any big surprises. Some customers make a choose not to go through insurers to ensure they get a speedy resolution and so it does not impact future premiums.
CEO of Subsidence Ltd
