Underpinning a house to strengthen its foundations becomes necessary in the event of subsidence – when unstable soil causes the foundations to sink – or if you want to add extra floors.
Either way, underpinning technologies have advanced rapidly in recent years, and several different methods are now available.
Because of the complexities of the job, it’s difficult to predict exactly how long an underpinning project will take, but on average it works out at around four to six weeks.
However, some underpinning or restumping jobs may take longer, especially if unforeseen snags arise – a particular problem in older houses.
- Utility lines may need to be relocated.
- HVAC (heating, ventilation and air conditioning) systems may have to be modified.
- Basement stairs could need extending or rebuilding.
The Underpinning Process
Underpinning begins with digging out the ground around the foundations. This is followed by the actual underpinning process. Three techniques popular among Melbourne underpinning contractors are:
- Concrete underpinning.
- Placing reinforcing beams.
- Resin injection.
Concrete underpinning is often used for smaller jobs. It involves pouring concrete into excavated cavities. As the concrete sets, it forms a new foundation underneath the existing one. It entails the use of formwork moulds and reinforcing steel wires to ensure the concrete is the right shape and size.
Reinforcement Beams for Underpinning
Reinforcing beams – or piles – are driven into the ground or fitted into drilled holes until they’re anchored in stable soil.
Resin Injection Underpinning
With resin injection underpinning, small holes are drilled into the ground around the foundations and filled with environmentally-friendly resin.
Need a Free Underpinning Evaluation?
An experienced Melbourne underpinning contractor will be able to give you a better idea of how long your underpinning job will take – by carrying out a free inspection of your home.
They can also take care of all the preparatory admin work including getting the necessary permits.