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Bedrock and Load-Bearing Strata

Load-bearing strata or bedrock is an important layer of soil. It can provide an anchor to prevent a settling foundation from sinking further.

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Let’s explore the world of bedrock, one of the most important geologic formations on Earth. They’ve been around for many years and support many of the world’s largest structures. Without bedrock, construction would be a problem, especially in areas with weak or shifting soils. 

Are you wondering what bedrock is and the role it plays on construction sites? Read on to learn about it. 

bedrock

What Is Load-Bearing Strata? 

Below the earth’s surface lies a contiguous mass of rock that can support the foundation of your entire building or structure without sinking, settling, or shifting. It’s known as the bedrock or load-bearing strata. 

As well as being inert, bedrock does not contract or expand like the soils on the earth’s surface. However, they can get exposed in places with high erosion. 

When a home lies on sand or clay soils, it may start moving and sinking, and this might cause structural problems. Foundation contractors will underpin the foundation by driving piers down to the bedrock until they meet resistance. At 20 to 55 meters deep, the rock is so dense and can bear the weight that’s transferred to it via piers. 

Types of Bedrock 

Bedrock formation can fall into these three categories. 

Sedimentary rock: When pieces of rock (sediment) get carried to some basin or depression by air, wind, or water, they get trapped and buried over time. This loose sediment compacts and forms sedimentary rock. The resulting rock tends to be softer than other types of bedrock. 

Igneous bedrock: Any glassy or crystalline rocks that form when magma or molten lava cools off and solidifies on or below the earth’s surface falls within this category. They form when tectonic forces dislodge and deposit sedimentary rocks or metamorphic rocks into the hot mantle, where they melt and get ejected as magma, which cools off to form igneous rocks.                                                         

Metamorphic bedrock: Sometimes, bedrock can change due to forces such as heat or reactive fluids like salty water under the pressure of the earth’s crust. 

How Is Bedrock Depth Determined? 

There are many ways of determining the depth of load-bearing strata. Common techniques include digging, desk studies, and drilling. Because the depth of the bedrock varies from place to place, it’s essential to know what type of foundation can provide adequate support to your structure. 

Bedrock and Foundation Repairs 

If you experience settlement at some point in time, your local contractor will move quickly to stabilize your foundation back and potentially lift it back to its original elevation. They do this by driving piers down the ground into the stable bedrock to ensure structural integrity. 

Once the piers meet the load-bearing strata and resistance is established, they are load-tested to determine the proper depth they should be drilled to and the load they can carry. We use a simple math formula to measure torque to capacity while keeping in mind the soil type and their condition as well as the structure’s weight. 

Hydraulic lifts are then attached to your house. By applying pressure simultaneously, less pressure is used during lifting. Finally, the home gets lifted off the active soils and the structural load is transferred to the columns in the bedrock. 

Can You Build a Foundation on the Bedrock? 

Yes, it’s possible where there’s an outcrop or exposed layer of bedrock. But that’s not a common thing. If you were to build your foundation on top of the bedrock, you’d have to dig out tons of soil first. That’s not feasible or cheap for residential purposes. 

If your home’s foundation needs support due to settlement, contact the experts at Foundation Recovery Systems for a free foundation inspection and repair estimate. We’ll send out an inspector to examine your foundation, and one of our crews can carry out the necessary repairs quickly. We use industry-approved and proven underpinning solutions so you’re assured of lasting results.