Underpinning has saved millions of homes around the world from cracking, shifting and completely collapsing. It’s almost like a kind of miracle operation… except, instead of being performed by surgeons in white coats, it’s performed by a team of top engineers and tradies! If you’re new to the idea of underpinning, but you think your home may require it, you’re probably wondering just how the heck it works. After all, it does sound kind of crazy at first: digging up the ground around your home so that you can jack it up and keep it level. But the truth is, underpinning does work and it’s the only way to save a home from being damaged by moving soil. So, how does it work?
Underpinning extends the existing footings of a building so that it reaches more stable founding material, preventing the building from shifting. This can be established once a soil report is completed to determine where the geotechnical specialist requires the footings to be founded.
Different methods of underpinning
Underpinning has changed a fair bit over the years and there are a few different methods for different types of homes and their varying problems. Here are a few methods of underpinning which your ‘foundation surgeons’ might use to get your home back on track:
- Pit method
The pit method, one of the oldest forms of underpinning, involves extending the pre-existing foundation until the stratum is stable. Underneath the existing foundation, the soil is dug out carefully before being filled with concrete. The pit method is best suited to shallow foundations.
- Pier and beam method
In the pier and beam method, reinforced concrete beams are used to transfer the load to piers, which allow the concrete to be poured. This method is commonly used on buildings with deeper foundations.
- Micropiling underpinning
Micropiling, or mini piling, underpinning is a method of underpinning that’s commonly used when loads from the foundation have to be transferred to strata that is more than 5m in distance. This method is popular for when site access is limited, when the soil consistency is variable or when there are contamination issues. These mini piles are typically between 100 and 400mm in diameter.
- Screw or driven pile
For the screw pile method, your remedial builder will drive piles on either side of the wall to support the weak foundation. A needle that is connected to each pile will penetrate the wall, supporting it while the foundation is filled. The screw pile method is best used for highly reactive soil like soft clay.
So, now you’ve got a better idea of what your remedial builders, or ‘house doctors’ get up to when making your home all better. For a strong, healthy foundation, contact Victoria’s most skilled team in foundation repairs and construction: Techniblock! They’ve helped countless Melbourne homeowners restore their foundation, greatly extending the lives of their homes. Chat with the team at Techniblock to get your building back on track.