As your home or property ages, its foundation might not be as rock-solid as it used to be. A home inspection can confirm whether the foundation is underperforming or deteriorating, which means it’s time for professional underpinning.
Experts recommend professional underpinning to upgrade, reinforce, and strengthen concrete foundations. But you need to be cautious – outdated approaches can add weight to a sinking structure without reinforcing the strength of the ground.
Let’s look at different types of underpinning methods so you can choose the best outcome for your property.
The need for underpinning
Underpinning is the process of stabilising or strengthening the foundations of a building. It corrects issues like subsidence.
Underpinning methods are needed when building foundations become unstable. Without underpinning, a property can become completely unstable, risking the safety of its inhabitants and surrounding properties; it can also invalidate insurance.
Property foundations can lose their original stability over time because of:
- Original faults in the foundation from poor workmanship
- Nearby excavations, which have created ground movement
- Soil subsidence
- Additional weight from new extensions, exceeding the strength of the foundation
- Natural disasters, such as earthquakes, heavy rains, and sinkholes
It’s important to pinpoint the root cause of issues before assessing options for underpinnings. This takes professional skill, experience, and cutting-edge technologies.
Expert tip: Act fast if you see any signs of possible subsidence, such as cracks in the wall. Get a professional assessment as soon as possible. Early intervention means you’ll have a greater choice of underpinning methods. It also reduces the amount of work, thereby lowering the cost.
Key factors to consider when choosing an underpinning method
The most dedicated underpinning specialists will pay particular attention to understanding what might have caused the foundation’s symptoms. This is important to decide on the best line of treatment.
For example, we’ll look at:
- The underlying soil type and its conditions
- The depth of the foundation problem (a significant consideration for identifying underpinning foundation methods)
- The building’s structural load
- The extent of obvious issues, such as subsidence
- Site access and any broader environmental concerns
Once a full assessment has been carried out, we can identify and offer solutions. When you choose Raise + Relevel, these underpinning methods include a 100-year product guarantee, plus a 50-year workmanship guarantee.
Expert tip: Choose underpinning experts with a proven track record and strong warranties – craftsmen who stand behind their work. At R+R, our ground surgeons’ mission is: better service, guaranteed. We stand behind the quality of our products and workmanship, and offer the warranties to back that up. If the problem returns, we return.
Types of underpinning methods
Thanks to new technologies and methods, the best ground surgeons and releveling experts offer a variety of underpinning methods to suit different situations. In most cases, these new underpinning methods significantly outperform traditional underpinning, offering better results, with less disruption and cost.
Here are some of the main modern underpinning foundation methods now available.
Grout and resin injection
What it involves
Expanding polyurethane resin is injected into the ground around unstable foundations. The ground readily absorbs the highly expansive resin, which improves soil binding, compaction, and significantly increases the bearing capacity. It also fills any voids and reinforces the ground to strengthen the foundation.
Polymer resin injections and permeation grouting are the two available approaches. Permeation grouting is similar to resin injections, but it uses microfine cement and injection lances to bind loose soil, making it ideal for properties near the beach or on sandy ground.
Many of our clients are now choosing grout and resin injections instead of concrete. At R+R, we offer these injections to strengthen soil and offer effective underpinning with no excavation.
Best for
Quick results where the soil is loose or voided, movement is minimal, and there is low disruption.
Grout and resin injections are a great example of modern underpinning methods that offer clean work and fast results without disruption. However, they aren’t suitable for all situations, especially where subsidence is particularly advanced.
Distruption level
Low. This procedure requires no excavation and resin can be injected through small tubes driven into the soil.
Traditional concrete underpinning
What it involves
With traditional concrete underpinning, engineers dig out sections of the foundation in a staged sequence, then fill every pit with mass concrete to the level where the soil is stable.
There are two main types of traditional concrete underpinning: mass underpinning (also known as the Pit Method) and concrete piling.
- With mass underpinning, we add extensive underpinning around the existing base before the concrete pour.
- With concrete piling, concrete pillars are sunk into the ground and attached to the foundations to provide extra bearing capacity.
Best for
Older buildings with shallow foundations, or where significant issues need resolving.
Houses in Sydney, Canberra, and Melbourne still benefit from traditional concrete underpinning, as it enhances the foundation mass and reinforces the structure.
Distruption level
High. Traditional concrete underpinning is proven and effective for certain projects, but it’s a disruptive method that requires extensive excavation; it may also mean relocating the foundation.
Mini-piled and screw piles
What it involves
As the name suggests, mini-piled underpinning adds narrow steel piles with screw-like blades into the foundation. These effectively transfer the building’s load weight to firm ground. They’re ideal for adding under existing foundations, and for jobs where space is restricted.
Best for
Sites with poor soil near the surface, challenging access, or where we need to achieve adjustable lifts.
Distruption level
Low-Medium. Mini-piled underpinning and screw piles are less invasive and have a high load capacity. They are also ideal where access and space are a problem (for example, in dense urban areas in Melbourne, Sydney, and Canberra). However, they need specialised equipment, so the cost is usually higher.
Your Raise + Relevel ground surgeon can talk you through each aspect of the different types of underpinning methods, and help you to choose the one that’s best for your situation. Contact us today to learn more.
Expert tip: Act quickly for better options. Your R+R engineer will carry out a detailed assessment of your property’s situation before recommending the best types of underpinning.
With new methods (such as resin injections) now available, it’s often possible to avoid disruptive traditional concrete underpinning altogether. The important thing is to seek an assessment as soon as you start to see issues such as cracks in the wall, sinking, or obvious subsidence.
How to choose between the types of underpinning?
The choice of underpinning foundation methods available for your property depends very much on the quality of the assessment. It’s important to get this done by professionals such as Raise + Relevel, as you need to be sure that the recommended course of action is the correct one.
At Raise + Relevel, we are trusted groundwork engineers, not salespeople. We have no call centres and minimal overheads, which allows us to offer the best value to our customers. We also invest in the latest technologies and techniques that minimise disruption and time, and offer the cleanest work at the most affordable cost.
Your Raise + Relevel engineer will carefully assess the decision factors that influence the types of underpinning best for your property, including soil type, building type, and your budget. In all cases, our work is 100% guaranteed for quality and results, with a 100-year product guarantee and a 50-year workmanship guarantee.
Contact R+R today
Raise + Relevel is your first choice for professional underpinning. We blend guaranteed results with 50-year workmanship guarantees and 100-year product guarantees.
Our team has more than 100 years of combined experience, and we have successfully treated over 7,000 Australian homes in Sydney, Melbourne, and Canberra, with guaranteed lasting results.
We offer highly competitive pricing, trusted and reliable work, and the finest level of customer service. For the widest choice of underpinning methods, contact us today.
FAQs
What is the cheapest type of underpinning?
Among all the common types of underpinning, resin injection (or polyurethane resin injection) is typically the most cost-effective. Remedial builders use this underpinning method for quick, affordable, and clean results when ground shift is minimal.
Why is mass concrete underpinning still used?
Despite high-tech solutions such as resin injections, mass concrete underpinning is still reliable, proven, and suitable for smaller projects where subsidence is present for cost-effective results.
Which foundation repairs are the quickest?
Resin injections or mini piled underpinning are generally the fastest, cleanest, and most cost-effective types of underpinning methods, depending on the soil conditions and extent of ground shift. A structural engineer or remedial builder can offer professional advice.
