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Glossary of Foundation Repair Terminology
- Active Zone
- Depth of soil instability; typically, soil movement is due to variations in moisture; also called the Seasonal or Weather Effected Zone
- Bedrock
- A subsurface layer of earth suitable for supporting a structure
- Brick ledge
- Part of the foundation wall where the base layer of brick veneer is placed
- Brick lintel
- Angle iron on which brick is placed. Used above windows, doors, and other openings
- Canopy width
- Distance across the spread of the branches and leaves of a mature tree
- Catch Basin
- A hole, dug at a distance from the foundation, then filled with gravel, sand, or other porous material. A catch basin is designed to work with a french drain to drain water away from the foundation. Water held in a catch basin evaporates or is absorbed into surrounding soil
- Clay
- A naturally occurring mineral that is present in tiny particles. Clay traps and holds water within its molecules causing expansion or "swelling" of the soil. When water is withheld clay particles contract or "shrink". Clay is also called Expansive Soil or Gumbo.
- Concrete Slab
- Concrete that is typically poured in a single piece and serves as base support for a building. A slab foundation is reinforced with steel rebar and/or steel stressed cables, and other methods. Slab foundations may have footers made of the same materials. Required dimensions and components of slabs and footers may be dependent on local building codes. A concrete slab sits directly on surrounding soil. Also called Slab On Grade
- Differential Moisture Content
- A frequent source of foundation damage is the differential expansion of soil under and near the foundation. Moist soil is adjacent to dry soil. Differential Moisture Content can be caused by low areas that hold water longer than surrounding areas, watering of lawns and garden beds, absence of gutters which direct water away from the foundation, water leaks, etc.
- Elevation
- Measurements that determine the difference in height between the central point, of a building and other reference points
- Fill
- Soil or sand brought in to raise the elevation of a building’s foundation and provide a level construction surface. Properly installed fill moves water away from the foundation.
- Footer, Footing
- An object, usually part of a concrete slab, that provides support for the building’s foundation Footers help distribute the weight of the foundation and building evenly throughout the entire foundation
- Form
- Temporary structure, usually made of wood, built to hold concrete during the pour and initial hardening
- Foundation
- Supporting structure that transmits the weight of the of a structure and itself to the surrounding soil
- Foundation Ties
- Metal or plastic wires that hold the foundation panels and rebar in place while concrete is being poured
- French drain
- Perforated pipe or gravel bed installed underground to catch and divert water from the foundation. A french drain is graded to drain the accumulated water away from the site.If land is flat a catch basin and discharge pump may be necessary to contain water.
- Grade
- Ground level, or elevation at any given point. Excavation or building up then leveling of soil that will support a building’s foundation. Correct grading causes water to drain away from the building’s foundation.
- Grade beam
- A foundation wall poured level with or slightly below the grade
- Gumbo
- See clay
- Load Bearing Capacity
- Maximum load (weight) that can be applied over soil before it begins moving; also called shear failure
- Monolithic slab
- A concrete floor and concrete foundation placed at the same time to form a monolithic footing and slab
- Mud Jacking
- Procedure in which grout (typically a sandy loam, water and cement mixture) is pressure pumped under the foundation in multiple locations. Mud jacking is best used for small areas like driveways, sidewalks etc. It is not a good solution for a home or business foundation. The reason is that the applicator has no control over where the grout goes after leaving his equipment. The liquid material takes the path of least resistance so it can come up through the foundation in low areas and pipes that may not be firmly joined. In addition the back pressure from application can cause separation of plumbing pipes coming through the foundation. Because application is uneven results aren’t predictable. Once the grout has set up it is as difficult to remove as concrete. Mud jacking also tends to be a temporary method of repair. In order for the grout to hold the foundation in position it depends on the soil beneath it to remain in place. If the soil moves due to loss of moisture then the grout will not be able to hold the load.
- Permeability
- A measure of how easily water penetrates the soil; the test of soil permeability is called a perc or percolation test
- Piers, Piering
- Multiple steel posts are driven through unstable soil to bedrock. Then hydraulic jacks are used to stabilize the slab. The slab is held in place by the pier and the special bracket, attached to the pier, that holds and supports the slab.
- Rebar, Reinforcing Bar
- Ribbed steel rods that are placed in forms of foundations, concrete walls, and footers; concrete is then poured into the forms with rebar in place. Rebar strengthens the concrete
- Refusal
- The condition reached when a pile being driven by a hammer has zero penetration per blow or when the effective energy of the hammer blow is no longer sufficient to cause penetration
- Root Barrier, Barricade
- A root barrier is an impermeable material that is inserted into the soil driven into the soil to a depth of approximately three (3) feet. The barrier prevents tree roots from growing under a home’s foundation where they may rob the soil of moisture. Root barriers may be made from fiberglass, plexiglass, or other materials.
- Settlement
- - Refers to part of a foundation sinking below its original elevation; usually evidenced by interior and exterior cracks throughout the building
- Shear Failure
- See Load Bearing Capacity
- Sill Plate
- Bottom horizontal member of the exterior wall frame. The sill plate sits on top the foundation
- Skin Friction
- The resistance of the soil surrounding a pile to vertical movement of the pile
- Slab On Grade Foundation
- A building construction practice in which the concrete foundation slab is formed from a reinforced form (typically a wood frame) set into the ground; the concrete is poured into the form
- Stem Wall
- The vertical part of a concrete or masonry retaining wall
- Thickened-Edge Slab
- See monolithic slab
- Upheaval
- Refers to part of a foundation rising above its original elevation; like settlement upheaval, it is evidenced by interior and exterior cracks throughout the building
- Weep hole
- A small opening left in the outer walls of masonry construction as an outlet for water inside a building to move outside the wall and evaporate