Foundation underpinning is a reparation method that strengthens the existing foundations of a building below ground level. The process is often used for structures in which the foundations have moved and require specialist work to avoid further breakdown.
If property damage is left unresolved and requires underpinning, the cost of fixing the problem will increase the longer it is left, and may put your building at risk.
Why is underpinning needed?
If the soil beneath the present foundations of a structure has weakened, underpinning is a cost-effective method that includes repairing and improving foundations rather than replacing them entirely. Underpinning is usually imperative when the following occurs:
- The original foundation is not strong or stable
- The structure usage has changed
- There is requirement of a basement beneath an existing structure
- The soil supporting the foundation is showing signs of subsidence
- Earthquakes, floods or other natural causes have forced movement of the structure
A building usually needs underpinning when cracks are wider than ¼ inch and there are signs of a faulty foundation, particularly diagonal cracks.
Does your property require underpinning?
When subsidence occurs, the supporting soil within a foundation moves away from the structure, thus removing its support. The signs are not always immediate, however, you may notice cracks in the walls, windows or door frames. To ensure that you get the best results, you must select the correct repair method for your property.
What are the different types of underpinning?
The decision of underpinning work is made after a professional has examined the structure / if you’re in doubt, you should contact your local foundation contractors to gain an expert opinion. There are many different methods of underpinning, and it’s required that certain properties receive the right treatment.
Mass concrete method
This is the traditional type of underpinning and the method involves digging box-shaped voids by hand beneath the foundations of an existing structure and filling them with concrete. The final result is a solid foundation below the structure. For this process, heavy machinery is not usually required. The main benefit to using the mass concrete method is the simplicity of the installation.
Beam and base method
The beam and base method is a technical refinement of the mass concrete process and involves a reinforced concrete beam being installed above, below or to replace the current footing of a structure. The beam transfers the load of the building to mass concrete bases, this then spreads evenly for support. The construction of the beams depends solely on the architecture of the structure and the type of load applied to the foundation.
Mini piled method
These are most useful when access to the foundations is limited and ground conditions are variable. Mini-piles allow the load to be transferred down to stable grounds at depths greater than 5 metres. This technical process requires specialist skills and machinery and as a specialist foundations team, we can design and implement mini-piles regardless of the size of your structure.
How is underpinning accomplished?
At Dart & Co Foundations, we first assess the problem and value accordingly. Our expert groundwork solutions involve a number of methods including underpinning, piling and foundation repair and build.
As UK underpinning contractors, we are equipped to assess, design and install various types of structural foundations for various building types. If you’d like to talk to a member of our team about what to do next, give us a call on 08002061563 or fill out our contact form to request a response.