An important construction method that can be used to intensify and stabilise the foundation of the existing building is termed underpinning. When an existing building faces issues like settling, subsidence, and structural inadequacy, this procedure is essential to safeguard the building or structure. Various methods can be employed to stabilise the foundation based on the conditions and requirements of a specific project. The ultimate goal of employing various methods is to bring structural integrity and correct existing structural problems to provide long-lasting structures.
This article examines several underpinning techniques, their application, and their timing in strengthening different kinds of foundations.
What is Underpinning in Building Construction?
When unforeseen issues occur after construction is finished, the underpinning process is utilised to strengthen and repair the building’s foundation. Underpinning is required to promptly restore stability in the event that a footing or foundation breaks unexpectedly. To increase the overall safety of the structure, the process includes strengthening and deepening the current foundation with additional support.
What are the Common Methods of Underpinning?
When laying foundations, there are a few distinct methods that can be applied. However, the four methods listed below are the most popular ones:
Mass Concrete Underpinning

When extensive excavation is not necessary, this underpinning technique is employed. To strengthen the base, a concrete foundation is poured. This is a fairly simple foundation technique that doesn’t require large equipment. It is also a cost-effective approach.
Beam and Base Underpinning

This technique uses a conventional mass concrete base that is held up by beams to provide a sturdy foundation. In this type of underpinning, the beam that is built either above or below the concrete base will support the weight of the foundation.
Mini-Piled Underpinning

Mini-piled underpinning is a versatile technique that works well on a variety of soil types, including loose or soft ones, where conventional techniques are ineffective. It is perfect for crowded or built-up areas since it requires less excavation and causes less disturbance to the surrounding area.
Jet Grouting
In order to build columns and other structures in the ground, the jet grouting technique entails cutting the soil with a high-velocity jet of fluid or fluids and combining the eroded soil with a self-hardening grout.
When is Underpinning Necessary?
When an issue arises in the foundation of the existing structure, there exists an underpinning procedure. The following are the common situations where underpinning is essential to perform.
Foundation Failure
When the foundation of the building or structure is not stable, reinforcements should be added to safeguard the existing structure without it falling or collapsing. It can also be possible when there is a poor foundation. The base soil should be strengthened to avoid uneven settlements.
Change in Building Usage
If there is any potential change in the use of the existing structures, you may choose this underpinning method. If you improve the strength of the foundation, then the load-bearing capacity of the building may increase tremendously and be apt for the intended use.
Soil Condition Changes
Different soils have different properties over time, such as deformable soils, decomposing soils, and so forth. The foundations may move as a direct result of this. In these situations, efforts are made to improve the soil conditions.
Adjacent Construction
The existing structure is significantly impacted by the excavation of adjacent structures. Therefore, if proper shoring is not implemented, it is essential to prevent or avoid the negative effects to ensure stability and prevent structural damage.
What are the Benefits of Underpinning?
The purpose of underpinning is to prevent the existing structure from falling or collapsing. Several benefits of underpinning are as follows:
Enhanced Structural Stability
Commonly, your existing building or structure is affected by a poor foundation due to various reasons like worsened weather conditions or just being worn out. To resolve this issue, underpinning is employed to strengthen your foundation and ensure that it is shielded from various disasters in the upcoming years. This results in providing safer shelter for the occupants.
Increased Property Value
The fact that underpinning raises the value of your property is among its biggest benefits. A well-built structure with completed underpinnings will be worth more when you decide to sell your property in the future, and you can expect a healthy return on your investment.
Accommodation of Additional Loads
If you want to change the potential load-bearing capacity of your property, you can use the underpinning method. It can increase the structural integrity of the building as well as its potential to bear greater traffic.
What Should You Consider Before Underpinning?
Only skilled professionals should manage the intricate process of underpinning. Hiring a qualified contractor with an emphasis on underpinning is advisable. Here are some important things to think about:
Cost:
As underpinning can be costly, it’s frequently used as a last resort to repair damaged or weakened foundations. Costs can be significant because of the dangers. To make sure it works within your budget, always get an estimate before beginning.
Insurance:
Before beginning any underpinning work, notify your insurance provider. Your policy will be modified to include coverage for the renovations. If you neglect this step, your insurance may be nullified, leaving you vulnerable in the event of an emergency.
Permit:
Make sure your contractor has the required permits for construction. Ignoring them at first could result in financial and legal problems, reduce the value of your home, and make insurance more difficult. Verify the competence of the contractor before starting the process. It is even better to check when you are searching for an underpinning expert.
Conclusion
A clever, economical, and less intrusive method of resolving issues of your existing building or structure and adding more space to your current structure is underpinning. Underpinning can help you save money and offers long-term advantages by strengthening your foundation. You can have peace of mind and a stronger, more resilient home or property by fortifying your building now to prevent future expensive repairs.
FAQs
A professional underpinning expert can be able to give you a permanent solution for your poor foundation.
The cost of the underpinning procedure starts from Rs. 500 per square metre. Depending on the method, size, location, and materials involved, it may vary as per project requirements.
In some cases, if the internal walls are affected, then you must move out; otherwise, you don’t need to relocate while the underpinning is going on.
Based on the complexity of the project, it may take around four to six weeks to complete the underpinning process.
Some risks are always associated with underpinning. It requires more skill and attention to take care of the process. It’s better to consult an expert before undertaking underpinning your building or existing structure.