What is used when the subgrade is too soft to provide adequate bearing for a normal footing?

What is used when the subgrade is too soft to provide adequate bearing for a normal footing?

• A. Piles
• B. Piers
• C. Concrete blocks
• D. Stone footings

Answer: (A)

When the ground beneath a footing isn’t strong enough to support the load, foundations must reach down to firmer soil or rock. Piles do this by extending the foundation deep into layers with adequate bearing, transferring the building load to those deeper strata. They can work through end-bearing on a hard layer or by friction along the shaft, and come in various types (driven, drilled) and materials (wood, concrete, steel) depending on the site. Concrete blocks, stone footings, and typical piers rely on the surface or near-surface soil for support and would tend to settle or fail on soft subgrades, so they don’t provide the necessary bearing without deeper support.

When the ground beneath a footing isn’t strong enough to support the load, foundations must reach down to firmer soil or rock. Piles do this by extending the foundation deep into layers with adequate bearing, transferring the building load to those deeper strata. They can work through end-bearing on a hard layer or by friction along the shaft, and come in various types (driven, drilled) and materials (wood, concrete, steel) depending on the site.

Concrete blocks, stone footings, and typical piers rely on the surface or near-surface soil for support and would tend to settle or fail on soft subgrades, so they don’t provide the necessary bearing without deeper support.