How Much Does It Cost To Underpin A House In Sydney?

The average cost to underpin a house in Sydney is between $5000-$40000. There are two main variants: how bad the damage is and how much work to do to fix it. For large houses that need a lot of work to improve, the cost can be up to $80,000.

In this article, we’ll explore all the factors that affect the cost of underpinning. You’ll also learn about various underpinning methods and how they can increase or decrease your total price.

What is Underpinning? 

Underpinning is a process to increase or restore the load-bearing capacity of a foundation. The most common methods of underpinning are traditional concrete underpinning and screwpile underpinning.


In most cases, the change in the soil moisture level weakened the original foundation. As a result, underpinning is required to increase the foundation’s strength. Underpinning is also used when we need to add height to a structure. 


What Are The Different Underpinning Methods?

Two different types of underpinning methods msot popular to underpin a house are Traditional Concrete Underpinning and Screwpile Underpinning. Each has specific benefits and drawbacks that sometimes make it more or less ideal.

Concrete Slab Underpinning 

In Concrete slab underpinning, the contractors dig deep enough to get a solid surface and pour concrete into the hole to support the foundation. The technique is very safe and only takes a short while to apply.

Screwpile underpinning

In this process, long and large steel screws are driven deep into the ground. The top of each screw is then encased in concrete to strengthen the surrounding soil. The screwpile needs to place deep enough to get a solid surface to support it. After the excavation crew reaches the required depth, they will pour concrete to secure the perimeter. 

What Should You be Looking for in an Underpinning Quote? 

Be sure that your quotes match any of these methods:

Fixed time frame:

Before you hire a contractor, get a detailed timeline from them that covers every task that needs to be completed and how long each will take. It will help you to be sure that your project will complete timely.

Fixed Price Quotation 

Another great deal could be to get a fixed-price quote from your contractor for your underpinning. That means, your contractor will give you an estimate after looking at your project. The contractor cannot charge you more than what was agreed upon in the quote, meaning you can finish the project with no additional expenses. Nevertheless, make sure that all required tasks are included in the initial quote to avoid misunderstandings.

Clear Quote 

When looking for quotes, be sure that the pricing is transparent. The company should give you a detailed explanation of the underpinning process, so there are no hidden charges. Also, make sure everything is included.


It would be best to get quotes from multiple contractors to compare prices and choose the best option for your needs.

If you still want to know more details about what is underpinning, you can check our other blog here.