What is Underpinning? Process, Types, and Key Considerations
When it comes to preserving old buildings, underpinning stands out as the most crucial aspect of construction. It plays a vital role in strengthening foundations under buildings to ensure maximum safety and stability of the structures. This technique is commonly used in areas with weak soils, like London, to help existing buildings support additional floors.
The technique of underpinning in London is applied before constructing a new floor on a single-story building that is built on foundations unable to bear more weight. It is also implemented to safeguard a building with foundations sinking into the ground.
How is Underpinning Work?
Underpinning is not a single-step process; it involves various procedures. All these aspects play a crucial role in the successful completion of this effective construction process, and skipping or neglecting a single one can ruin the whole effort and money.
Here’s a detailed description of each step involved in the underpinning process.
Site Visit
The very first step in the underpinning technique is the site visit. Engineers visit the particular building that requires underpinning to evaluate the structure's condition. It helps them to understand the crucial soil properties and the cause of foundation issues.
It provides them with important details to select the right type of underpinning technique.
Selection Phase
After the site assessment, the next step is the selection of an appropriate underpinning technique. It depends on the root cause or reason of the foundation issues and future challenges.
Engineers make sure to design an underpinning solution catering to the specific needs of the building.
Underpinning
Before starting the underpinning, engineers go through the excavation process. It takes place beneath the existing foundation in sections. It is crucial to ensure the structure remains supported throughout the underpinning process.
Engineers apply the selected underpinning method meticulously and safeguard the structures.
Continuous Inspection
After completing the underpinning process, continuous inspection and testing are also essential. It helps the construction teams perform their job accurately. It enables them to detect problems and check the effectiveness of the solution before and after completing the process.
Different Underpinning Techniques
Construction contractors use different types of underpinning techniques, depending on the site location and building needs. Underpinning these techniques is the need to make the right decision and save both time and money.
Screw Piling
Apart from strength and a strong foundation, the underpinning technique is also used to minimise noise and vibrations. For this purpose, screw piling is the most commonly used technique. The reason is that it offers a quicker, economical, and environmentally friendly solution for foundation issues.
This technique required extensive excavation and curing times. In this method, helical steel piles are screwed deep into the ground, where they provide a strong base.
Jet Grouting
For loss and unstable soil, the Jet Grouting technique is the most effective one. It not only provides a strong base but also strengthens the overall building.
In this method, grouts are injected into the ground, which results in a solid and stable mass. Therefore, it provides incredible strength to the base foundation.
Mini-Piled Underpinning
Underpinning techniques selection based on the soil condition and various other factors. For areas with limited access and challenging soil conditions, engineers usually prefer the Mini-piled technique.
This method simply employs small-diameter piles to achieve the desired strength.
Mass Concrete Underpinning
It is one of the most common underpinning techniques that has been used since ancient times.
It involves simply digging holes under the existing foundation and then filling them with concrete to strengthen the base. It may seem simple, but careful analysis of the holes' depth and their filling is crucial to avoid any trouble in the future.
Piled Rafts Underpinning
This technique is used to transfer the building loads deeper through a raft or slab. It utilises rafts or piles to create a more stable and robust base for buildings. It is suitable for areas with more soil challenges because it effectively distributes the load of the structure.
Key Considerations
Underpinning is a complex process, and a slight mistake can result in multiple troubles. Therefore, careful consideration of the following factors is paramount to success.
● The credibility and experience of the construction company offering underpinning in Hertfordshire is the most fundamental thing to consider because they can directly impact the effectiveness of the solution.
● The next thing that needs your consideration before going for the underpinning process is the weather broadcast, because adverse weather conditions can impact its effectiveness.
● Considering unforeseen ground conditions is also essential to avoid before starting the excavation and underpinning process.
● The workers' security and the protection of surrounding buildings are also important things that you must consider before going for this crucial construction process.
A Final Word
Understanding the key underpinning strategies and preventive measures is an ideal approach to maintaining the structural integrity of the buildings. It allows you to choose the right technique, avoid costly mistakes, and pave the way for sustainable and enduring constructions that can carry heavy loads and stand strong for years.
