Methods of Underpinning

Underpinning is a process used to repair, strengthen, or increase the depth of an existing Structure by deepening the base to allow it to rest on more supportive soil. The process of underpinning starts with the removal or excavation of soil from beneath the foundation. There are three methods of underpinning.

Mass Pour

Mass pour is the most widely used method of underpinning. The greatest advantage of this method is its low cost and ability to handle heavy foundation loads. In mass pour method a concrete foundation is poured beneath the existing foundation in sections. It is a simple method of underpinning and does not require any heavy machinery.

Mini Piled

Mini Piled method is best for those sites where soil condition are variable and the access areas around the foundation are limited. In this method, ‘piles’ or deep vertical structural elements are screwed into the ground holes deep enough to allow the piles to rest on stable soil. While this method is best suited for any adverse soil condition, the process can be quite expensive due to the expertise involved.

Beam and Base

Beam and base method is a technically advanced method. In this method, a reinforced concrete beam is constructed below the foundation to replace the existing footing. The new concrete beam is responsible for transferring the load to a mass concrete base which spreads the load evenly across the soil.