Glossary Of Terms For Home Foundation Repair
Active Zone - The active zone refers to the depth of soil instability or movement, usually due to moisture variation. It is also called the Seasonal Zone.
Bell Bottom Pier - A Bell Bottom Pier is a vertical structural support built to support concrete slab foundations and is built of concrete and steel rebar. Its name is derived from the bottom of the pier, which resembles a bell and provides a greater area of support for the pier (22 inches) and the concrete slab above it. Click the following link to view a diagram and explanation of Bell Bottom piers. Click the following link to learn more about the History of the Bell Bottom Pier.
Clay - Clay is a naturally occurring earthy mineral that is plastic when wet but becomes permanently hard when heated. Clays are formed by the weathering of feldspathic rock. Clays are composed of hydrated aluminum silicates, such as kaolinite, illite, palygorskite, attapulgite, bentonite, and montmorillonite. Clay exhibits significant volume expansion when exposed to water and significant compression when water is withdrawn. (see "Gumbo" below)
Concrete Slab - A concrete slab (foundation) is an area or strip of concrete laid as a single unjointed piece to serve as the foundation for a home or building. Modern concrete slabs are always reinforced with steel rebar or steel cables. Underneath it is supported entirely by surface soils. (Most homes built in Texas are built on concrete slabs.) Click the following link to find out more about warning signs of foundation problems.
Differential Moisture Content - Adjacent areas of soil with different moisture content can cause concrete slab / home foundation movement. Trees and drainage problems are the most common causes of differential moisture. Click the following link to learn more about the problems trees cause with home foundations.
Elevation - Elevation is a series of measurements to determine the difference in height between a central point and other points.
Footing - Footing is any physical object (such as a Bell Bottom Pier) that provides support for a home foundation by distributing the weight over a greater area of the supporting soil.
Foundation - A foundation is that part of the structure that is in direct contact with the ground. The foundation transmits the weight of the entire structure (home) and itself to the supporting soil.
Gumbo - Gumbo refers to a variety of fine-grained silty soils (usually clays) found in the western and southern portions of the United States. (see "Clay" above)
Load Bearing Capacity - This term refers to the maximum load or weight that can be applied to the soil before movement or failure (also called shear failure). The soil under the home foundation is under constant pressure from the weight of the home.
Mudjacking - Mudjacking (also called mud pumping) is a process used to fill voids and add additional support under home foundations / concrete slabs. It is usually a cement / soil mixture and is pumped under pressure underneath the foundation. Click the following link to see more information about the mud pumping process.
Pressed Piling Piers - A system of pressed piling piers is a series of concrete cylinders pressed into the ground to provide support for a concrete slab. Click the following link to view a diagram and explanation of Pressed Piling Piers.
Pressed Piling Piers with Insert - A system of pressed piling piers with insert is similar to pressed piling piers with one significant difference. Similarly, it is also a series of concrete cylinders pressed into the ground to provide support for a concrete slab. However, the concrete cylinders have holes in the center in which a metal rod or insert is placed. Click the following link to view a diagram and explanation of Pressed Piling Piers with Insert.
Root Barricades - Root barricades are overlapping sheets of non-biodegradable 1/4" thick plexiglass driven into the soil to a depth of approximately 30 feet. Their purpose is to help prevent tree roots from growing too close to a home's foundation. Click the following link to view more information concerning root barricades and tree roots.
Settlement - This term refers to a process or situation where part of a home's foundation has moved BELOW its original elevation. It usually results in interior and exterior cracks in various places throughout the home. Settlement can occur when there is compaction of fill, a loss of soil due to erosion, or a loss of moisture in the soil that is supporting the concrete slab foundation. The most common area of settlement is the perimeter of the concrete slab because it is more susceptible to loss of moisture in the underlying soil. When clay soils lose moisture they can shrink dramatically in volume. (see "Upheaval" also)
Slab - Please refer to the definition of "Concrete Slab" above.
Soaker Hoses - A unique rubber hose around the perimeter of a home or building that can be placed on top of the soil or up to 24 inches below the surface. These hoses are designed to distribute a low-volume, low-pressure flow of water around the perimeter of a slab foundation. The goal is to have a uniform level of moisture around the structure which in turn will minimize the potential of soil movement to damage the concrete slab.
Pressed Steel Pilings - A system of pressed piers used in a method similar to the pressed piling method. Steel pilings are used in areas with drier soil conditions such as Dallas, Fort Worth, Austin, and San Antonio. Click the following link to view a diagram and explanation of Pressed Steel Pilings.
Upheaval - This term refers to a process or situation where part of a home's foundation has moved ABOVE its original elevation. It usually results in interior and exterior cracks in various places throughout the home. The most common cause of upheaval is the introduction of excessive moisture / water under the concrete slab. The most common cause of excessive moisture / water under the concrete slab is a plumbing leak in the drainage system. (see "Settlement" also)
Water Leaks - Water leaks are a huge problem for home foundations. Usually, they result from leaks in the plumbing system but other sources can contribute to water accumulation under a home's concrete slab. Water leaks can cause upheaval (swelling and expansion of the clay soil) and settlement (soil compaction). Click the following link to read more about under slab plumbing leaks and how they can impact a home's foundation.