Foundation Glossary

Basement Foundation

A basement foundation is a foundation that places a full level of the house below ground, with walls around it that carry the house above and also hold back the surrounding soil.

Basement Moisture vs. Water Seepage

Basement moisture versus water seepage is the difference between dampness that comes from water vapor, condensation and slow wicking, and seepage, which is liquid water pushing through pores, cracks or joints in the foundation.

Basement Water Intrusion

Basement water intrusion is liquid water entering a basement or lowest level from outside the foundation or from a failed pipe, appearing as damp patches, seepage, trickles or standing water.

Concrete Compressive Strength

Concrete compressive strength is the squeezing load a concrete mix can carry before it fails, divided by the area carrying it, and it is reported in pounds per square inch (psi).

Concrete Foundation Wall Bowing

Concrete foundation wall bowing is when a below-grade wall has bent, bulged or leaned, most often inward, because of pressure from the soil and water outside it.

Concrete Pier Foundation Repair

Concrete pier foundation repair is a method of underpinning a house with short precast concrete cylinders that are stacked and pressed into the soil one by one with a hydraulic jack, using the weight of the building as the reaction, then capped and shimmed to support the foundation.

Concrete Spalling

Concrete spalling is the breaking away of chips, flakes or larger pieces from the surface of concrete, which leaves a rough, shallow or deep pit.

Cracks in Slab Foundations

Cracks in slab foundations are breaks in the concrete slab that forms a house floor and foundation, caused by shrinkage as the concrete dried, by temperature, by loads, or by movement of the soil beneath, and read as clues, not as a diagnosis.

Crawl Space Foundation

A crawl space foundation is a foundation that holds a house’s floor above the ground on short perimeter walls, leaving a low, enclosed space beneath it.

Diagonal Foundation Cracks

Diagonal foundation cracks are cracks that slant across a foundation wall rather than running level or plumb.

Differential Foundation Movement: see Differential Settlement

Differential Settlement

Differential settlement is uneven settlement, where one part of a foundation sinks more than another.

Differential Soil Movement: see Differential Settlement

Downspout Drainage Away From Foundations

Downspout drainage away from foundations is the set of gutters, downspouts, extensions and pipes that collect rain from a roof and release it far enough from the foundation that it cannot pool against the walls or soak the soil under the footing.

Drilled Piers

Drilled piers are cast-in-place concrete foundation elements made by drilling a deep round hole, placing reinforcing steel and concrete in it, and carrying the building load down to a soil or rock layer strong enough to support it.

Expansive Clay Soil

Expansive clay soil is clay-rich ground that swells when it takes in water and shrinks when it dries out, changing volume enough to push up or pull away support from a foundation, slab or wall.

Expansive Soil and Foundation Movement: see Expansive Clay Soil

Exterior Foundation Drainage

Exterior foundation drainage is a system of perforated pipe, gravel and a drainage layer placed outside a foundation, usually beside or just below the footing, that collects soil water and carries it to a gravity outlet or sump.

Fill Soil and Foundation Settlement

Fill soil and foundation settlement is what happens when a footing or slab rests on soil that was placed by people, not formed in place, and that soil compresses over time because it was loose, uneven or not tested when it went in.

Foundation

A foundation is the part of a building that carries the structure’s weight into the ground.

Foundation Crack Width and Monitoring

Foundation crack width and monitoring is the practice of measuring how wide a crack is at a marked spot, and re-measuring the same way over time, so change can be seen and reported, instead of judging a crack by one look.

Foundation Cracks

A foundation crack is a break in a concrete or masonry foundation; its direction, width and change over time are clues to the cause, not a diagnosis.

Foundation Dampproofing

Foundation dampproofing is a thin coating or treatment on the outside of a below-grade foundation wall that slows the passage of soil moisture into the concrete or masonry.

Foundation Design and Building Codes

Foundation design and building codes are the legal rules that set how a foundation must be designed and built, usually drawn from a model code such as the International Residential Code (IRC) and then adopted, and often amended, by a state or local government.

Foundation Drainage

Foundation drainage is the combination of surface grading, gutters and downspouts, subsurface drains and outlets that keeps rain, snowmelt and soil water from collecting against a foundation.

Foundation Efflorescence

Foundation efflorescence is a white or light-colored deposit of soluble salts on the surface of a concrete, block or brick foundation wall, left behind when water carries the salts to the surface and evaporates.

Foundation Expansion Joint

A foundation expansion joint is a planned separation, usually filled with a compressible material, that lets one part of a concrete structure move independently of another part.

Foundation Footing

A foundation footing is the wide base at the bottom of a foundation that spreads the weight of a wall, pier or column over enough soil to carry it.

Foundation Heave

Foundation heave is upward movement of a foundation, slab or wall caused by the ground rising beneath it.

Foundation Inspection

A foundation inspection is a visual examination of a foundation and the clues around it, such as cracks, slopes, gaps, drainage and grade, made to describe its condition at one point in time and to say whether further evaluation is needed.

Foundation Load-Bearing Capacity: see Soil Bearing Capacity

Foundation Maintenance Checklist

A foundation maintenance checklist is a list of safe, repeatable homeowner tasks that keep water away from the foundation and soil moisture steady, and that record changes early.

Foundation Movement Monitoring

Foundation movement monitoring is the practice of measuring a house at set intervals, with crack gauges, floor-level readings or survey targets, to learn whether the structure is moving, in which direction, and whether the movement is changing.

Foundation Problems When Buying a House

Foundation problems when buying a house are signs of movement, water or past repair at the structure that raise the risk of the purchase.

Foundation Repair

Foundation repair is work to stop or correct movement in a home's foundation, from drainage fixes and crack sealing to piers, slab lifting and wall stabilization.

Foundation Repair Contractor

A foundation repair contractor is a company that installs piers, lifts slabs, stabilizes walls and fixes drainage; it is paid to repair, not to give an independent diagnosis.

Foundation Repair Cost Factors

Foundation repair cost factors are the things that move a quote up or down: the cause of movement, repair method, number of piers or linear feet, access, soil, permits and engineering.

Foundation Repair Credentials and Licensing

Foundation repair credentials and licensing is the set of legal permissions and professional claims behind a foundation company or engineer.

Foundation Repair Documentation

Foundation repair documentation is the set of written and photo records that show what was wrong, what was agreed, what was built and what was promised.

Foundation Repair Estimate

A foundation repair estimate is a written statement from a contractor of what work they propose, with what materials and on what schedule, and what they will charge for it.

Foundation Repair Financing

Foundation repair financing is any arrangement that lets a homeowner pay for repair over time instead of in one payment, such as a loan against the home’s equity, a personal loan or a payment plan offered through the contractor.

Foundation Repair Insurance Coverage

Whether homeowners insurance pays for foundation repair depends on the policy wording, the cause of the damage and the exclusions; settlement, earth movement and wear are commonly excluded.

Foundation Repair Red Flags

Foundation repair red flags are warning signs in how a repair is sold, priced, contracted or paid for that tell a homeowner to slow down and check.

Foundation Repair Scope of Work

A foundation repair scope of work is the written description of exactly what a repair will include: the work, the locations, the materials, the engineering and permits, the schedule and what is left out.

Foundation Repair Second Opinion

A foundation repair second opinion is a separate evaluation of a diagnosis, a repair scope or a price, from a party other than the first one you asked.

Foundation Repair Timeline

A foundation repair timeline is the sequence of stages from first assessment to final sign-off, with the dates each is expected to start and finish.

Foundation Repair vs. Foundation Replacement

Foundation repair versus foundation replacement is the choice between keeping the existing foundation and correcting or supporting it, and removing it to build a new one.

Foundation Repair Warranty

A foundation repair warranty is the contractor's written promise about what it will fix and for how long; its limits, exclusions and transfer terms matter more than the headline term.

Foundation Repair Warranty Transferability

Foundation repair warranty transferability is whether a repair warranty stays in force when the home is sold, and on what terms.

Foundation Settlement

Foundation settlement is the downward movement of a foundation as the soil beneath it compresses, shrinks or loses support.

Foundation Settlement vs. Foundation Heave

Foundation settlement versus foundation heave is the contrast between a foundation moving down and a foundation moving up.

Foundation Stabilization: see Foundation Underpinning

Foundation Subsidence

Foundation subsidence is the downward movement of a foundation because the ground it sits on has lowered.

Foundation Types

The main residential foundation types are slab-on-grade, crawl space, basement and pier and beam, each a different way of carrying a house's weight into the ground.

Foundation Underpinning

Foundation underpinning is the process of adding remedial supporting elements, such as piers or piles, under an existing foundation so the building rests on deeper or stronger soil than the soil that settled.

Foundation Uplift: see Foundation Heave

Foundation Wall Displacement: see Concrete Foundation Wall Bowing

Foundation Waterproofing

Foundation waterproofing is the set of measures that keep liquid water from passing through below-grade walls and floors, usually a membrane or coating on the outside of the wall working together with drains that carry water away from the footing.

Foundation Waterproofing vs. Dampproofing

Foundation waterproofing versus dampproofing is the distinction between a foundation treatment built to resist water under pressure and a lighter coating that only slows soil moisture.

French Drain for Foundation Drainage

A French drain for foundation drainage is a trench filled with gravel that holds a perforated pipe, built to collect water in the soil and carry it by gravity to an outlet away from the house.

Frost Heave

Frost heave is the upward movement of the ground caused by ice lenses that grow in freezing soil when water is drawn toward the frozen layer, lifting whatever rests on it, including slabs, porches and footings placed too shallow.

Geotechnical Soil Investigation

A geotechnical soil investigation is a study of the ground at a site, done by a geotechnical engineer through site reconnaissance, borings, sampling, field tests and laboratory tests, and written up in a report of what the soil layers, water and behavior mean for the foundation.

Grading Around a Foundation

Grading around a foundation is the shape and slope of the ground next to a house, set so that rain and melt water run away from the walls instead of toward them.

Groundwater and Foundation Problems

Groundwater and foundation problems are the damp, leaking, pressure and soil-softening effects that follow when water held in the ground, often a high or seasonal water table, rises to or above the level of a foundation wall or floor.

Helical Piers

Helical piers are steel shafts fitted with one or more spiral plates that are rotated into the ground until they reach a layer able to carry the load, then connected to a foundation by a bracket so the structure rests on that deeper soil.

Home Inspection and Foundation Problems

Home inspection and foundation problems refers to the part of a general home inspection that reports what an inspector can see of the foundation and structure on one day.

Horizontal Foundation Cracks

Horizontal foundation cracks are cracks that run roughly level along a foundation wall, often across the middle of a block or poured basement wall.

Hydrostatic Pressure on Foundation Walls

Hydrostatic pressure on foundation walls is the force that water in the surrounding soil exerts against a basement wall and floor.

Hydrostatic Pressure vs. Soil Pressure: see Hydrostatic Pressure on Foundation Walls

Independent Foundation Inspection: see Foundation Inspection

Interior Foundation Drainage System

An interior foundation drainage system is a network of drain pipe and gravel, placed inside a basement along the footing or under the floor, that collects water and carries it to a sump pit for pumping or gravity discharge.

Load Path in Residential Buildings

A load path in residential buildings is the chain of connected parts that carries forces from where they act, such as the roof, walls and floors, down through the foundation into the soil.

Mudjacking

Mudjacking, also called slabjacking, is a repair that raises a settled concrete slab by drilling holes through it and pumping a cement-based slurry beneath it, so the slurry fills voids and pushes the slab back up toward its original level.

Negative Grading: see Grading Around a Foundation

Pier and Beam Foundation

A pier and beam foundation is a foundation that holds a house’s raised floor on spaced vertical piers topped by beams or girders, leaving open space under the floor.

Plumbing Leaks and Foundation Damage

Plumbing leaks and foundation damage is the link between water escaping from a supply, drain or irrigation pipe near or under a house and the movement of the foundation, since leaked water changes soil moisture and soil movement can also break pipes.

Polyurethane Foam Slab Lifting

Polyurethane foam slab lifting is a repair that raises a sunken concrete slab by drilling small holes through it and injecting a two-part polyurethane that reacts, expands and hardens into a lightweight foam under the slab, filling voids and pushing the slab up.

Push Piers

Push piers, also called resistance piers, are steel pipe sections pressed hydraulically through a bracket under an existing footing until they reach firm soil or rock, so the foundation rests on that deeper layer instead of the soil that moved.

Push Piers vs. Helical Piers

Push piers vs helical piers is a comparison of two steel deep foundation systems that support a settling building: push piers are pressed down against the building’s weight and carry load at their tips, while helical piers are rotated in and carry load on spiral plates.

Questions to Ask a Foundation Repair Company

Questions to ask a foundation repair company are the set of checks a homeowner puts to a bidder before signing.

Reinforced Concrete Foundation

A reinforced concrete foundation is a foundation of concrete with steel reinforcing bars embedded in it, so that the steel carries the pulling forces that concrete resists poorly and the concrete carries the pushing forces.

Reinforcing Steel in Concrete Foundations: see Reinforced Concrete Foundation

Seasonal Soil Moisture Changes

Seasonal soil moisture changes are the rise and fall in the water content of the ground through the year, driven by rain, snowmelt, heat, plants and drainage, and in clay soils they make the ground swell when wet and shrink when dry.

Shallow Foundation vs. Deep Foundation

A shallow foundation is one that passes a building’s load to soil near the surface through footings, a slab, a crawl space or a basement, while a deep foundation is one, such as a pile or drilled pier, that reaches through weak upper soil to firmer ground below.

Signs of Structural Foundation Damage

Signs of structural foundation damage are visible clues that a foundation or the ground under it may have moved, such as growing cracks, sticking doors, sloping floors or bowing walls, which call for a licensed engineer to interpret.

Slab-on-Grade Foundation

A slab-on-grade foundation is a concrete slab poured directly on the ground, with no basement or crawl space beneath it.

Soil Bearing Capacity

Soil bearing capacity is the amount of pressure the ground under a footing can carry from a building without shearing or settling too far, so a foundation can pass its load safely into the soil.

Soil Compaction

Soil compaction is the process of pressing soil particles closer together, usually with controlled moisture and heavy equipment, so fill under slabs, footings and backfill is dense enough to settle very little after a house is built.

Soil Consolidation

Soil consolidation is the slow settlement of saturated, fine-grained soil, such as clay, as water is squeezed out of its pores under a load.

Soil Consolidation vs. Compaction: see Soil Consolidation

Soil Erosion Around Foundations

Soil erosion around foundations is the loss of soil from beside or beneath a house when moving water, such as roof runoff or flood flow, carries it away, leaving walls and footings with less cover and less support.

Soil Plasticity Index

The soil plasticity index, or PI, is the difference between a soil’s liquid limit and its plastic limit, which is the range of water content over which the soil can be molded without crumbling or flowing.

Stair-Step Cracks in Brick and Block Walls

Stair-step cracks in brick and block walls are cracks that follow the mortar joints in a zigzag, rising like the steps of a staircase.

Stem Wall Foundation

A stem wall foundation is a foundation in which a short wall of poured concrete or concrete block rises from a footing to the underside of the floor or slab.

Structural Assessment vs. Foundation Inspection

Structural assessment vs foundation inspection is the difference between an engineer’s investigation of why a structure is in its condition and an inspector’s visual survey, which only describes what can be seen.

Structural Engineer for Foundation Problems

A structural engineer is a licensed professional who evaluates how a building carries loads and can write a repair plan for a foundation problem without selling the repair.

Structural Engineer vs. Foundation Repair Contractor

An engineer diagnoses and designs; a contractor builds and installs. Getting both opinions on a major repair separates the diagnosis from the sale.

Sump Pump System

A sump pump system is a pit set below a basement floor, with a pump, a float switch and a discharge line, that collects water from drains and soil and pumps it away from the house.

Tree Roots and Foundation Movement

Tree roots and foundation movement is the link between a tree drawing water out of the soil and the ground under a nearby foundation shrinking and settling, which happens mostly in clay soils that change volume with moisture.

Vertical Foundation Cracks

Vertical foundation cracks are cracks that run straight up and down, or nearly so, in a foundation wall.