How to treat subsidence

Subsidence treatment depends on one thing above all else: the cause.

Before any repair work begins, you must confirm:

• Is movement ongoing?
• What is causing it?
• Is the structure at risk?
• Is intervention necessary?

Not all subsidence requires underpinning. In fact, many cases can be stabilised with far less disruption.

If you’re unsure how subsidence is confirmed, read: How is subsidence diagnosed?

Step 1: Fix the cause first

Structural repair without addressing the cause can lead to recurring movement.

Depending on the diagnosis, treatment may begin with:

Drain repair

Leaking drains are repaired before any structural work. Once soil washout stops, the ground may stabilise naturally.

Tree management

In clay soil areas, managing moisture demand from trees can reduce seasonal movement.

Tree removal should always be assessed carefully — removing large trees can cause heave.

Monitoring only

If movement is historic or seasonal but stable, the safest treatment may be continued monitoring rather than structural intervention.

Sometimes, doing nothing is the right engineering decision.

Step 2: Choose the right structural solution

If foundations require support, there are typically three options:

1. Do nothing (if stable)
2. Traditional underpinning
3. Modern ground stabilisation

Let’s look at these clearly.

Option 1: Do nothing

If monitoring confirms:

• Movement has stopped
• Cracks are historic
• There is no ongoing structural risk

Then cosmetic repair may be sufficient.

Engineering should be proportionate — not reactive.

Option 2: Traditional underpinning

Underpinning involves:

• Excavating beneath foundations
• Pouring concrete below existing footings
• Deepening the foundation base

Underpinning typically means:

• Large trenches around the property
• Internal floor removal in some cases
• Weeks or months of disruption
• Higher carbon impact
• Potential alternative accommodation

Underpinning is sometimes necessary — particularly for very deep or severe movement — but it is not always the only solution.

Option 3: Ground stabilisation using geopolymer injection

Modern ground improvement techniques can stabilise foundations without excavation.

Geopolymer injection works by:

• Drilling small holes through the floor or externally
• Injecting expanding geopolymer resin
• Filling voids
• Strengthening soil
• Re-supporting foundations

The material expands, compacts weak ground and restores load-bearing capacity.

The benefits include:

• No excavation
• Minimal disruption
• Installation in days
• Up to 70% faster than traditional methods
• Up to 90% lower carbon footprint
• No need to move out

For many residential properties, this offers a lower-disruption alternative to underpinning.

Geobear vs underpinning – what’s the difference? 

Every case is assessed individually. The right solution depends on soil type, severity and foundation depth. 

What about insurance?

Many homeowners assume they must go through insurance.

There are pros and cons.

Pros:

• Insurer manages contractors
• Alternative accommodation arranged
• You pay only the excess

Cons:

• Longer timelines
• Potential premium increases
• Limited choice of contractor
• Underpinning history may affect resale perception

Because geopolymer solutions do not involve excavation, they often avoid the stigma sometimes associated with underpinning.

Speak to a subsidence specialist

We know how stressful subsidence can feel.

Our approach is simple:

• Clear explanation
• Honest assessment
• The least disruptive solution
• Engineering grounded in evidence

Because fixing the ground properly means you can move forward with confidence. Learn more with our What is subsidence guide.