Underpinning is a dynamic procedure used in construction and building maintenance to support and alleviate a building’s foundation. However, one of the most frequently asked questions by homeowners and property developers is: How long does an underpinning project last? The answer depends on numerous factors, but a basic understanding of the underpinning process and the Underpinning London role can help to clarify.
What is Underpinning?
Underpinning comprises deepening or supporting the groundwork of an obtainable building. This is typically done when the current foundation is no longer stable or strong enough to support the structure. It may be essential for a variety of motives:
Subsidence:
When the ground beneath a foundation sinks or shifts, it can destabilise the building.
Changes in Load:
The existing foundation may need reinforcement if additional stories or extensions are added to a building.
Soil Conditions:
Foundations may require underpinning if the soil is unstable, such as clay soils that expand and contract with moisture.
Foundation Damage:
Cracks or other damage to the foundation can compromise its strength and require underpinning for repair.
How Long Does an Underpinning Project Last?
The period of an underpinning project can differ depending on various factors, including the extent of the building, the importance of the underpinning required, and the selected method of underpinning. Generally, underpinning can take anywhere from a few weeks to several months.
Type of Underpinning Method
Mass Concrete Underpinning:
This traditional method involves excavating ground sections beneath the foundation and filling them with concrete. It is time-consuming and often requires weeks to complete, depending on the size of the property and the number of underpinning sections needed.
Beam and Base Underpinning:
This method involves installing reinforced concrete beams and bases beneath the existing foundation. It’s quicker than mass concrete underpinning but can take several weeks.
Mini-Piled Underpinning:
This method is faster for smaller projects or those with challenging soil conditions. It involves installing small piles that support the building’s weight, and the work can be completed within a few weeks, though it depends on access and site conditions.
Hydraulic Underpinning:
This advanced method involves using hydraulic jacks to lift and stabilise the foundation. It’s generally quicker but requires specialised equipment, and the time required can vary depending on the complexity.
Size and Complexity of the Property
Larger buildings or properties with complex structures require more extensive underpinning work. This may involve multiple foundation sections, greater excavation, and reinforcement work. The larger and more complicated the building, the longer the underpinning procedure will take.
Ground Conditions
The condition of the soil under the building can disturb the time of the underpinning project. If the soil is soft, unstable, or prone to subsidence, additional work may be required to stabilise the ground before beginning the underpinning process. Contractors may also need to install deep foundations, which can increase the project’s duration.
What Do Underpinning Contractors Do?
Site Assessment and Planning
Before any work begins, underpinning contractors thoroughly assess the building and the surrounding area. This includes checking the foundation’s condition, evaluating soil conditions, and identifying any structural issues that must be addressed. Based on this evaluation, they improve a comprehensive plan for the underpinning procedure, including the process, materials needed, and equipment.
Excavation and Foundation Preparation
Once the plan is in place, contractors begin excavation beneath the existing foundation. They carefully dig out sections of soil to expose the foundation and create space for the new underpinning. This process requires precision, as any damage to the foundation during excavation can compromise the entire project.
Underpinning Installation
With the foundation exposed, contractors install the underpinning system, which may involve pouring concrete, installing piles, or using other materials, depending on the chosen method. The aim is to provide extra support to the existing foundation, distributing the weight more evenly and preventing future movement or subsidence.
Reinforcement and Finishing Touches
After installing the underpinning, contractors allow time for it to be set and cured properly. Once hardened, they reinforce the new structure and ensure it is securely integrated with the existing foundation. The contractors may backfill the excavated area and restore the ground to its original state.
Final Inspection and Testing
Once the underpinning work is complete, the project undergoes a final inspection. This includes checking for stability, ensuring all building codes are met, and testing the foundation’s strength. If any issues are found, contractors will address them before considering the job finished. Focusing on foundation work, CJB Piling offers a range of solutions, including driven piles, mini piling, and foundations for several types of soil and ground conditions.
