Selecting the right foundation is the key to building a stable and strong house. When the foundation is stable, it will transmit the weight from the walls to the load-bearing strata and keep out water.
Soil composition, building size, and topography are some of the things that will determine the type of foundation you’re going to install under your house. Let’s explore the term bedrock/load-bearing data, and show you how foundation piering is done.
What Is Load-Bearing Strata?
Bedrock, or load-bearing strata, is the underlying rock or stable soil that can carry the weight of a home or building without compressing or moving. Such soils are dense and non-active, hence, they won’t expand or contract like sand or clay.
When Is It Necessary?
Homeowners who live in areas with soft soils know that only deep load-bearing strata can bear the weight of their homes. Load-bearing strata that go 20 to 65 feet below the ground can provide adequate structural support. It will also protect your home’s structural integrity.
Types of Deep Foundations
Deep foundations aren’t just used to support huge buildings. They’re also used to support the load of structures or homes that are built on steep locations, over water, and on sandy beaches. Here are some of the common types.
End-bearing piles: When the soil beneath a structure is unable to support its load, foundation contractors will have to bypass this weak layer to reach the stable bedrock, which will keep a home stable. They will drive strong columns into the ground, which will transfer the weight to the rock layer.
Friction piles: Made from H-shaped steel or concrete, these systems facilitate the exchange of forces with soil adjacent to the columns. How much of a load a friction pile can bear depends on its length. Because each pile has an area of influence, the columns have to be spaced out evenly for proper weight distribution.
Caisson foundations: These foundations are used to support bridges, freeway overpasses, and hillside constructions. They can be prefabricated or floated to the job site.
The Piering Process
Underpinning the foundation is a process that starts with a site survey and ends with restoration. The exact process may look different depending on which type of piering solution is used. Push piers are typically used for homes and heavier buildings, helical piers are best for lighter structures, and slab piers are specific to slab foundations.
Your foundation contractor will notch out the footings first. They will then attach the pier bracket to the footing using anchor bolts and drive the sleeve to the ground using protractors. This ensures piers go straight down when they’re being installed.
Next, push piers are driven through the ground one at a time using the building’s weight and the adjacent soil as counterweight until they get to the bedrock (load-bearing data).
Once the piers encounter resistance, they are load-tested and the data at each placement is recorded. This data enables structural engineers to determine the right piering depth and the appropriate load-bearing strata. Engineers will correlate the bearing capacity to hydraulic pressure. They will also factor in the condition of the soils on-site, the structure’s weight, and environmental loads.
After piering the foundation, hydraulic lifting rams and lifting head assemblies are attached to the piers in a sequence. This enables the lifting ram operator to apply pressure to the piers simultaneously. The benefit of doing this is that less pressure will be used to lift the structure.
Finally, the home or building is transferred from the weak or failing strata to the load-tested piers on the solid strata before the nuts of the pier caps are tightened and the lifting ram removed. The structure will now rest close to the original elevation.
What’s the Best Foundation Solution for Me?
There’s no one-size-fits-all foundation solution in home construction. You have to consider your building’s location, size, and on-site geotechnical factors before you settle for a particular foundation. As for how deep the foundation will go, that depends on the type of underlying soil. Make sure the ground is stable and solid enough to support your structure before you start building your house. Are you experiencing sinking or settling in your Denver, CO, home? That’s a sign the foundation is built on weak or unstable ground. Complete Basement Systems can examine your foundation and recommend a solution to underpin the base of your home or building. Schedule a free foundation repair inspection and quote to get started.