What is the difference between restumping and underpinning?

Restumping and underpinning are two different foundation repair processes. Restumping is performed for houses built on stumps, while underpinning is used for homes with slab or strip footings.

In this blog, we’ll discuss how differently restumping and underpinning work and how to know if your home needs either repair process.

What is restumping? 

Restumping is a process to change or replace your damaged house stumps with new stumps.. 

Restumping and reblocking are the same process and are often used interchangeably. To learn more about this process, please read this blog posts.

The three most often used materials for stumps have different benefits and drawbacks. They are as follows:

Timber Stumps

Despite being the most popular type of restumping in the late 1960s and 1970s, timber is also the most vernarable to termite and moisture damage.

Concrete Stumps

Although it’s more expensive than timber, over time, it will become cheaper because it’s more durable. So, in the long run, it’s a value-for-money investment.

Steel Stumps

Steel is the most expensive yet most durable among these three restumping materials. We use steel stumps when the height between the subfloor and ground exceed 1.8 meters, specified by an engineer or in particularly reactive soils.

If you’re curious how long does it take to restump a house, we have all the answers in this helpful blog post.

What is Underpinning? 

Underpinning is a foundation reinforcing or stabilising process where large slabs of concrete below a footing, distributing the weight of a building equally and reinforcing the foundation. It can only be done when the building structure is built on a slab or a strip footing.

There are several methods used for underpinning a house. They are –

  •     Traditional concrete underpinning
  •     Piling
  •     Micro-piling
  •     Screw piles
  •     Jet grouting
  •     Geo-polymer resin injection

Traditional  Concrete Underpinning 

Concrete mixture was poured into dug holes around the foundation to reinforce it.


Piles are driven deep into the ground to support the foundation using concrete or steel piles.


It’s a mix of mass concrete and piling. It uses small diameter piles to strengthen the foundation.

Screw Pile 

The process involves driving a screw-shaped steel pile deep into the ground until it reaches the required torque.

Jet Grouting 

In this process, a high-pressure water jet digs holes into the soil to pour concrete. As a result, they create a column-like structure that helps to reinforce the foundation.

Geo-polymer Resin Injection 

Geopolymer resin is injected into the ground to raise the building’s footing.

Is underpinning the same as Restumping?

No, underpinning and restumping are two very different foundation repair processes. If a house is built on stumps, damaged stumps can be replaced with new ones in a process called restumping. In contrast, if a building is constructed on top of a slab or strip footing, that structure will require underpinning to stabilise its foundations.

How do I know if my house is built on stumps? 

If you see these around your house, you can be fairly sure they are on stumps:

– The building structure is suspended above the ground.

– Stumps made of timber, steel, or concrete is visible underneath your subfloor

– You have vents around the outside of your house

How do I know if my house is built on a slab? 

If your house is not elevated from the ground and no stumps are visible under your subfloor, you can be sure that it is built on a slab. 

If you need restumping or reblocking, this blog post is for you. We’ve outlined the differences between restumping and underpinning, as well as how to determine if your house is built on stumps or a slab. We’ve also provided information about how long each process typically takes. So, whether you need a quick fix or want to prepare for the future, we hope this blog has helped provide some clarity.