The soil underpinning Adelaide is notorious for being highly reactive, meaning that it can expand and contract rapidly and dramatically enough to cause significant structural damage to buildings. This phenomenon is particularly noticeable during periods of severe drought, where the structural walls shift so much, they crack glass windows and show screens.
While new construction projects have the luxury of using the latest techniques to mitigate the effects of reactive soil, existing houses aren’t so lucky. Instead, homeowners have to rely on several foundation repair methods to shore up their foundations to prevent any future structural damage.
If you’re shopping around for reliable methods for stabilising your foundation, you may have run into lots of technical terms that get complex very quickly. We aim to provide you with a short introduction to the various types of foundation repair, their advantages and disadvantages, and which one is the best option for you.
Types of Foundation Repair
Underpinning is a process of reinforcing the footings of a foundation to make it stronger. The traditional underpinning process requires you to first expose and excavate the original footings and then reinforce them, traditionally with steel and concrete. The result is a straighter, more level house that can resist soil movement.
Several different methods are used in traditional underpinning, depending on the current situation. These include:
- Mass Pour: The simplest method involves excavating sections underneath the footing and pouring a concrete mixture into the hole. Each footing is underpinned in sequence until the entire structure is complete. This default method has the advantage of simplicity but may be unsuitable in certain complex situations.
- Jacking over Underpins: This method strengthens the footings and can jack them up to level the building. Unfortunately, this method doesn’t work well in wet soil, since the suction can prevent lift.
- Screw Piles and Brackets: Sometimes, it’s impractical to use a piling rig to excavate underneath the footing. In this case, builders can use screw piles to excavate and brackets to complete the pinning. The main advantage of this method is that it’s much faster than mass pouring and causes fewer vibrations.
- Pile and Beam: Pile-and-beam underpinning is a targeted strengthening method that uses multiple mini-piles supporting a needle beam. The beam, in turn, supports a particular wall. This entire assembly can be incredibly rugged, and it’s a faster method of underpinning than mass pour.
- Piled Rafting: Builders will only use piled rafting if an entire structure needs additional support. If the foundations are too deep or the soil is too hard to excavate, piled rafting offers a strong and economical alternative. It works in a similar way to pile and beam, but the needle beam is linked with ranked beams to form a raft, which gets poured with concrete for extra strength.
Chemical underpinning is similar to traditional underpinning, but with one key difference. Instead of relying on concrete as the supporting material, chemical underpinning uses a specifically engineered resin that’s flexible and resilient.
The advantage of Urathane Solution’s patented chemical underpinning method is that mimics the soil’s natural behaviour by sealing the soil and breaking the cycle of excessive wetting and drying.
Our resin is chemically engineered to properties similar to a synthetic caulk, providing flexibility to withstand natural soil movement and long term stable foundations. The lifting and setting process can be control with millimetre precision thanks to proprietary and innovative engineering.
Pressure Cement Grouting Underpinning
Significantly less common than traditional or chemical underpinning, this method uses cement grout instead of cement or engineered resins to strengthen the footings. To underpin foundations, builders will often use cement grouting under dams or rock formations where access to the foundation is difficult.
This method is more common for industrial applications, but very few home-building and foundation repair companies advocate its use to strengthen home foundations.
This is not a suitable application for repairing subsiding footings or foundations such as concrete slabs or concrete strip footing.
Which One Should You Choose?
If you live in Adelaide, you know how unruly our clay soil can get. Underpinning is a well-established method of strengthening and repairing foundations. At Urathane Solutions, we recommend using chemical underpinning due to the unique properties of the polyurethane resin. This resin works well in highly reactive soils, where it can absorb changes in soil size and prevent structural damage to your home.
If you want to know more about underpinning in Adelaide, don’t hesitate to get in touch. Our team of experts is on hand to give you all the advice you need to keep your home in excellent shape.