The Use of Ground Anchors to Support a Foundation

Soils

• There are different types of soil. The basic idea in most building codes is to build only on soils that can bear weight without shifting. “Weak” soils have much air in them. This is another way of saying that the soils are not compacted properly and make poor building conditions. The solution is to dig a very deep foundation that reaches the more compacted and rocky soil. These foundations may well require ground anchors to keep the whole structure from shifting along with the soil. If a foundation looks to be shifting the house, then a foundation repair firm might add these anchors to balance the weight of the home on the shifting soil.

Settlement

• Foundations do not last in soil conditions that are not load bearing. Soils need to be tested before building can commence, and, in general, weaker soils with much air cannot be built upon. Soils do, however, change. If soils dry out and become thinner over time, the house can then settle. The weaker the soil, the more a house will settle or sink, leading to severe structural damage. If a new house is built on weak, thin, "dusty" soil, the initial settling can cause foundation damage. This is even more relevant for high-rises and skyscrapers, where tons of weight are bearing down on a fairly narrow base.

Installation

• The general method of installing soil spikes or anchors is to attach long, metal pipes from the bottom of the concrete foundation upwards. The pipes are anchored in the concrete foundation itself. The pipes are grouted with zinc or copper for corrosion resistance. This creates a web of metal that keeps soil from shifting and bringing added weight to the foundation walls. At the same time, these spikes keep the foundation itself balanced in shifting soil conditions in the same way that a tightrope walker uses a long pole to keep himself from falling.

Buildings

• Most kinds of ground anchor are used in large buildings like hospitals and universities. In residences, since most houses are not built on air-saturated soils, these become less relevant for residential building. They are very relevant, however, for high-rise apartments, skyscrapers and buildings that have many stories. Since tall buildings are top-heavy, anchors are used to keep the entire structure balanced.