Underpinning: What is it?
Within the construction industry, underpinning refers to the process of strengthening and stabilizing the foundation of an existing building or structure. It is generally required when there has been damage to the existing foundations or when the usage of the structure has changed.
For more details, check out: https://en.wikipedia.org/wiki/Underpinning
When should you consider underpinning?
Damage to the foundations of buildings will usually present visibly as cracks in the walls or in concrete floors. At this stage, building experts would look at different methods of underpinning to figure out which one would be most suitable to fix the foundations of the building.
If your foundations are not damaged but you are looking to add additional storeys to a property or change the usage of the building, you may want to consult an expert about how you can use underpinning to strengthen the foundations. This will ensure that they withstand the increased loads placed on them and help to prevent damage long term.
This training guide from the Australian government provides more information on why you might consider underpinning.
How does underpinning work?
To achieve the best underpinning results, builders will need to dig underneath shallow footings and extend the foundations of a structure. This will generally be done by pouring concrete to extend the foundations in either/both depth or/and breadth. The purpose of this is to either rest the foundations on stronger soil, or to distribute the load of the structure across a greater area.
Traditional underpinning is a process that is over a century old however with new developments in technology and excavation machinery there have increasingly been new underpinning methods available on the market.
What are the different types of underpinning?
There are a number of different methods of underpinning with each of them being appropriate for different types of structures with differing foundational requirements.
The different methods include:
- Mass Pour
- Screw Pile and Brackets
- Pile and Beam