What is Foundation Underpinning?




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Posted By: bayarea on 15th February 2017 Category: Foundation Repair

The Home Underpinning Process Explained

Here at Bay Area Underpinning, one of the most common foundation repair methods that we use is known as foundation underpinning. This process can effectively lift and stabilize foundations of all kinds to reverse foundation settlement and close foundation cracks. It is the ideal choice for foundations that have started to settle due to soil compaction or erosion. But what exactly is foundation underpinning?

Underpinning is a foundation lifting procedure that utilizes steel piers installed underground to raise concrete slabs and foundations. If your slab has settled due to foundation failure, foundation piers can be installed to lift the foundation back to the proper level and provide long-term stabilization. These piers bypass active, moving soils in the ground and provide support by anchoring into non-active and stable soils deep under the surface.

The steps in the underpinning process are as follows:

  1. First, the area is prepared. Landscaping may need to be moved or covered, and utilities may need to be disconnected. The installation area near the footing where the pier will be attached must be excavated and prepped.
  2. Next, the pier is installed. To install the pier, the repair team attaches a bracket to the foundation and drives the pier into the ground. The pier is extended into the ground (using multiple steel extensions) until it reaches solid ground. Some kinds of piers (usually for concrete slabs) can be installed without the removal of soil.
  3. Next, the piers are lifted using a hydraulic manifold lift (this system allows the piers to be lifted at the same time, ensuring that the foundation is raised evenly). This step raises the foundation back to the appropriate level and helps close any cracks that may have opened as a result of pressure from the foundation settlement.
  4. Once the piers have been installed and raised, the repair is complete. The final step is to clean up the jobsite, seal cracks, and remove any equipment.

There are the general steps in the underpinning procedure. However, these steps may vary based on the type of foundation piers used. Bay Area Underpinning uses the line of steel piers from ECP (Earth Contact Products), the number one foundation repair product manufacturer in the industry.

Slab Piers – For Lifting Slab Foundations

Foundation slab piers are used for homes and other structures that have a concrete slab foundation. ECP offers both mechanical and hydraulic options for slab piers and can be used for both poured grade and floating slabs. The slab piers that we use here at Bay Area Underpinning range from 8 kips to 40 kips (1 kip = 1000 lbs of force). These piers are installed in a grid pattern and placed five feet apart. Slab piers are the best solution to lift both home foundation slabs and garage slabs in the Bay Area.

push pier bay areaPush Piers – For Adjustable Repair Solutions

Push piers are a fully adjustable solution that are great at lifting slabs and foundations that have settled unevenly. These piers can be installed from both the interior and exterior of the foundation, depending on the type of foundation and the specific issue. For push piers, we use both the ECP Concentric Piers and the ECP Eccentric Piers (PPB-300 Model Steel Piers). These piers are individually driven to ensure the appropriate level of lift is applied across the entire foundation.

resistance pierResistance Piers – For Deep-Driving Repairs

The resistance piers that we use from ECP are ideal for driving deep into the soil to support foundations. The piers that we use for this solution are part of the Model 300 piering system, a standard in underpinning repairs. These piers are well-known as the strongest and deepest driving piers in the business. All of these piers are also load-tested before they are installed to ensure that they provide the necessary lift and support for your Bay Area foundation.

Helical Piers – For Added Stability

Helical piers are a great solution for extra stability in foundation underpinning. Because these piers are screwed into the ground and not merely pushed in, they offer added stability. These piers are most often used for light structural loads and in unstable rock foundations. Helical piers can be installed in all kinds of weather and offer immediate load transfer upon installation. These piers are installed hydraulically with a predetermined torque to support your foundation’s weight. We then install brackets that support the structure. View ECP’s helical piers here and see a video of helical pier installation on this page.

Concrete Piers – For Long-Term Support

Similar to the concrete piers that hold up bridges and other structures, our concrete piers provide long-term stability and are a cost-effective option for repairing foundations and preventing future settlement. The concrete piers are positioned and then driven into the earth using a hydraulic press. The foundation can then be appropriately lifted using a hydraulic jack. Once the foundation has been lifted, spacers are positioned to support the lifted foundation on top of the piers, the jack is removed, and the area is cleaned up. Another benefit to concrete piers is that they can be removed from the ground and reused if necessary. These piers offer a lower cost alternative to other kinds of foundation piering in certain situations.

For a free estimate on foundation underpinning in the San Francisco Bay Area of California, call Bay Area Underpinning today!