Underpinning Explained: When Is It Necessary in Sydney?

July 3, 2025

Underpinning Explained: When Is It Necessary in Sydney?

Noticed new cracks creeping across your walls? Floors sinking in one corner of the house? It might be more than just age or wear and tear, it could be your foundation shifting. In cases like this, underpinning may be the best way to stabilise and protect your home for the long haul.


But what exactly is underpinning, and when do you need it? Here’s what Sydney homeowners should know.


What Is Underpinning?

Underpinning is a structural repair method used to strengthen and stabilise the foundation of a building. It typically involves extending or reinforcing the existing footings to rest on more stable soil or a deeper level.


Depending on the property and the soil conditions, this may include:


  • Concrete piers poured beneath existing footings
  • Steel screw piles driven deep into stable ground
  • Resin injection (in some minor settlement cases)
  • Traditional mass concrete underpinning (for older buildings)


The goal of underpinning is to stop further movement and restore the structural integrity of your home.


When Is Underpinning Necessary?

Not every home that moves needs underpinning, but in some cases, it’s the safest and most effective solution. You might need underpinning in Sydney if:


1. Your home is built on a slab or strip footings

Homes without stumps or piers can’t be relevelled the same way raised homes are. If the slab or footing has sunk, underpinning is often the only viable method to lift and support it.


2. You see signs of serious structural movement

If you notice:

  • Wide or expanding cracks in bricks or plaster
  • Windows or doors that no longer align
  • Sinking on one side of the house
  • Gaps opening up between walls and floors

…it’s time to get a professional inspection.


3. You’re extending or renovating

If you’re adding a second storey or building an extension, existing foundations may not be strong enough. Underpinninghelps carry the extra load and is often required for engineering approval.


4. Soil instability or erosion is present

In some parts of Sydney, particularly on clay soils or near waterways, the ground can shift significantly over time. Tree roots, leaking pipes, or poor drainage can also erode soil beneath your home.


What’s the Difference Between Underpinning and Reblocking?

While both are forms of structural levelling, they apply to different types of foundations.

Reblocking or restumping is used for homes on timber or concrete stumps


Underpinning is used for homes with slabs or strip footings (typically brick or concrete homes)

If you're not sure what kind of foundation you have, a site inspection will confirm it.


Is Underpinning Permanent?

Yes, when done correctly, underpinning is a permanent solution. We use engineered supports designed to prevent further movement, restore stability, and provide long-term peace of mind. Like all foundation repairs, the key is getting it done early and by the right people.


How Much Does Underpinning Cost?

Costs vary depending on access, depth, and how many piers or piles are needed. On average in Sydney, underpinning ranges from:


  • $2,500 to $5,000 per pier, depending on site conditions
  • Full jobs often range between $15,000 and $40,000


We always provide a detailed quote after inspection, with no hidden extras.


Book a Free Underpinning Assessment

At Sydney House Leveling, we specialise in tailored solutions for all types of foundations, including professional underpinning for Sydney homes. If you’re worried about cracks, sinking, or movement, don’t wait.


We offer:

Free onsite inspections

Honest advice — no upselling

Fully engineered underpinning solutions

Fixed quotes and timeline commitments


📞 Call us on: 0478 566 483
📩
Or book online at: service@sydneyhouselevelling.com.au


Let’s get your home supported properly, from the ground up.

Metal support jacks installed under a wooden beam in a dark crawlspace, providing structural support.
August 18, 2025
Concrete vs. Steel Underpinning: What’s Best for Sydney Homes? When foundation issues strike, underpinning is often the best solution to stabilise and level your home. But which method should you choose— concrete underpinning or steel underpinning ? Both are effective, but the right choice depends on your home’s construction, soil type, and how severe the foundation movement is. Here’s a breakdown to help Sydney homeowners make an informed decision. Concrete Underpinning: The Traditional Choice What It Is Concrete underpinning involves digging under your existing foundation and pouring concrete to create a deeper, stronger footing. Pros Proven and Reliable – A traditional method with decades of successful use. Cost-Effective – Generally cheaper than steel underpinning for standard residential jobs. Great for Large Areas – Ideal for homes with widespread foundation movement. Cons Slower Installation – Excavation and curing take time, so the process can take weeks. Messy and Disruptive – Requires significant digging around your home. Not Ideal for All Soils – Less effective in very loose or sandy soils. Steel Underpinning: The Modern Alternative What It Is Steel underpinning uses screw piles or driven steel piers installed deep into stable soil or bedrock, then attached to the foundation to lift and support the home. Pros Faster Installation – Can be completed in days, not weeks. Minimal Excavation – Less disruptive to gardens and landscaping. Ideal for Problematic Soils – Works well in Sydney’s reactive clay and sloping blocks. Immediate Load-Bearing – No waiting for concrete to cure. Cons Higher Cost – Steel is generally more expensive upfront. Not Always Necessary – Overkill for minor subsidence issues. Which Is Best for Sydney Homes? Both methods work, but here’s a quick guide: Choose Concrete Underpinning if… ✔ Your home has widespread subsidence or needs a large foundation area reinforced. ✔ You’re on a tighter budget and don’t mind a longer project timeline. Choose Steel Underpinning if… ✔ You’re on reactive clay soil (common in Western Sydney). ✔ Your home is on a sloping block or needs deep stabilisation. ✔ You want a fast, less disruptive solution . In many cases, engineers may recommend a combination of both methods, depending on your property’s unique conditions. Need Expert Advice? Choosing the wrong underpinning method can cost you more in the long run. If you’re noticing cracks, uneven floors, or doors sticking , it’s time to have your foundation professionally assessed. Talk to Sydney’s House Leveling Experts We’ll inspect your home, explain your options, and recommend whether concrete or steel underpinning is best for you. 📞 Call us today to book an inspection and get a tailored solution for your Sydney home.
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Noticed cracks in your walls? Doors sticking? Uneven floors? These are early signs of foundation problems—and if you delay repairs, you could be setting yourself up for bigger headaches (and costs) down the track. For Sydney homeowners, where reactive clay soils and changing weather conditions often cause foundation movement, underpinning can be the difference between a stable home and major structural damage.  Here’s why delaying underpinning repairs is never a good idea.
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If you’re dealing with foundation issues—cracks in walls, uneven floors, or sinking foundations—underpinning might be the solution. But how much should you expect to pay in Sydney in 2025 ? The truth is, underpinning costs vary depending on your home’s size, soil conditions, and how severe the damage is. Here’s a breakdown to help you budget before starting repairs. 
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