Over time, your house could develop signs of shifting or cracks along the foundation. While this can be frightening, it does have a remedy. Foundation underpinning is a construction process that installs footings to reinforce the current foundation of your home. Ideally, an underpinned foundation will last for years without suffering any damage. Therefore, an underpinned property could fetch more during a sale. The extract below details the residential underpinning process.
Step 1: Engineer's Assessment
Hire an engineer to examine the damaged foundation. Typically, the engineer will start by establishing the cause of the foundation damage. For example, it could be caused by erosion, soil settlement, subsidence or vibrations from plant equipment. The engineer will also assess whether the damage has affected other structural features such as the slab. The engineer will need the building's blueprints to establish the type and depth of the foundation. This will help them determine how best to conduct the underpinning works.
Step 2: Planning
Soil can significantly affect the stability of your foundation and how to execute the underpinning works. Therefore, the engineer will conduct a soil test to determine the soil supporting the foundation. For example, if the foundation rests on clay soil, it could be challenging to install footings due to the contraction of the soil.
Step 3: Hiring An Underpinning Contractor
Your primary concern when hiring an underpinning contractor is their ability to execute the works. Typically, the contractor should have successfully underpinned buildings in the past. Check the contractor's schedule to ensure that they are available when you need them. Additionally, examine that the contractor observes safety and has adequate insurance coverage.
Since underpinning works affect the core structural feature of your home, it would be wise to engage the services of a building surveyor. The surveyor will sanction the contractor's work to ensure they abide by the building code.
Step 4: Underpinning Works
There are different ways to underpin a building. They include:
- Mass concrete: It replaces the soil underneath the foundation with concrete. More or less, the contractor installs a new foundation beneath the existing one.
- Piled underpinning: The technique drives piles into the ground to support the current foundation. It is a preferred method when the soil below is stable enough to support the piles. This procedure can also increase the load-bearing ability of the structure.
- Resin injection: The contractor injects resin or grout into the ground to fill cracks and restore the stability of the foundation.
When conducting underpinning works, ask for an engineer's assessment, plan the works, hire an underpinning contractor and determine an appropriate underpinning method.