Glossary of Foundation Repair and Waterproofing Terms

Understanding foundation and basement terms doesn’t have to be confusing. Use this glossary to learn what common terms like “underpinning,” “sump pump,” and “egress window” really mean. Click on a term below to jump to the definitions for that service.

Foundation Repair

A broad category of techniques used to stabilize, strengthen, or restore the structural integrity of a home’s foundation. Common repair methods include underpinning, wall reinforcement, drainage correction, and crack sealing. The appropriate solution depends on the cause and extent of the damage.

Underpinning

A method of strengthening a foundation by extending it to more stable soil layers, often using piers or pilings.

Helical Piers

Steel shafts with helix-shaped plates that are mechanically advanced into stable soil layers. These are used to support and lift settling foundations with minimal disruption. They are ideal for lighter structures and areas with variable soil conditions.

Active Zone

The upper layer of soil near the foundation that undergoes seasonal moisture fluctuations. These changes cause the soil to expand when wet and shrink when dry, contributing to foundation movement and settlement.

Foundation Movement

Any shifting, settling, or heaving of a home’s foundation that alters its original position. This can be caused by expanding soils, poor drainage, or nearby construction activity. Left unchecked, movement can lead to serious structural damage.

Foundation Settlement

The vertical downward movement of a building’s foundation, typically due to soil compaction, washout, or shrinkage. Settlement becomes a concern when it is uneven (differential), leading to misaligned doors, sloping floors, and structural cracking.

Load-Bearing Soil

The layer of soil that is dense and stable enough to support the weight of a structure without significant shifting or settling. Foundation repair solutions aim to transfer structural loads down to this dependable layer.

Differential Settlement

Uneven sinking or movement of a foundation that occurs when parts of the soil beneath a structure compress more than others. This imbalance can cause visible cracks in walls and floors, sticking doors or windows, and even structural instability.

Service: Foundation Settlement Repair

Footing

A wide concrete base that supports foundation walls by distributing the load of the structure over a larger area of soil. Properly designed footings help prevent settlement and movement by anchoring the foundation in stable ground.

Basement Waterproofing

The practice of preventing water intrusion through basement walls or floors using drainage systems, sealants, membranes, and sump pumps. Effective waterproofing reduces moisture-related issues like mold, odors, and structural deterioration.

French Drain

A gravel-filled trench containing a perforated pipe designed to redirect groundwater away from a building’s foundation. Commonly installed along the interior or exterior perimeter to manage hydrostatic pressure.

Drain Tile

Flexible, perforated piping used in interior or exterior waterproofing systems to collect and move water to a sump pump. Modern drain tile is typically corrugated plastic and surrounded by gravel.

Sump Pump

A submersible or pedestal pump installed in a sump basin to automatically remove collected groundwater and discharge it away from the foundation. Critical for preventing basement flooding in areas with high water tables.

Check Valve

A one-way valve installed in the sump pump discharge line to prevent water from flowing back into the sump basin after it’s been pumped out.

Vapor Barrier

A plastic or foil sheet installed on walls or floors to block moisture vapor from passing into living spaces. Helps reduce humidity and protect insulation in finished basements.

Hydrostatic Pressure

The force exerted by water in the soil pressing against basement walls and floors. Over time, this pressure can lead to cracking, bowing, or water infiltration.

Efflorescense

A white, powdery residue left behind on basement walls when water evaporates and deposits mineral salts. While not harmful, it indicates moisture intrusion that should be addressed.

Weeping Tile

A porous or perforated pipe used to channel groundwater into a drainage system. Typically buried at the base of the foundation to relieve water buildup and reduce hydrostatic pressure.

Cove Joint

The seam where a basement wall meets the floor slab. This junction is highly susceptible to water intrusion and is often targeted in waterproofing system installations.

Egress Windows

A window designed to provide an emergency exit from a basement or lower-level living space. Egress windows are required by building codes for any basement bedroom and must meet minimum height, width, and clearance standards.

Window Well

A semi-circular or rectangular excavation around a basement egress window, typically reinforced with metal or plastic. Window wells keep soil and debris away from the window and often include drainage and a ladder for emergency escape.

IRC Code Requirements

The International Residential Code (IRC) sets guidelines for the size, height, and accessibility of egress windows to ensure safe exit during emergencies. Compliance is mandatory for finished basements that include sleeping areas.

Casement Window

A window hinged on one side that swings open like a door. Often used as an egress window due to its wide opening and easy operation.

Tempered Glass

A safety glass treated to increase strength and reduce injury risk. When broken, it shatters into small, rounded pieces rather than sharp shards. Required by code for egress windows installed below grade.

Dehumidifiers

A device that removes excess moisture from the air by cooling it and collecting the resulting condensation. Essential in basements or crawl spaces to maintain healthy humidity levels and reduce the risk of mold growth.

Relative Humidity (RH)

A measurement of how much moisture is in the air compared to the maximum amount the air can hold at a given temperature. RH above 60% in a basement can lead to mold and poor air quality.

Desiccant Dehumidifier

A type of dehumidifier that uses a moisture-absorbing material (desiccant) instead of refrigeration to extract humidity. Particularly effective in cooler environments like crawl spaces or unheated basements.

Drain Hose

A hose connected to a dehumidifier that allows continuous water drainage into a floor drain or sump pit, eliminating the need to manually empty the reservoir.

Humidistat

A built-in sensor in dehumidifiers that monitors humidity levels and turns the unit on or off based on the desired setpoint. Allows for automatic, energy-efficient moisture control.

Street Creep

Expansion Joint

A flexible joint in concrete structures that absorbs movement caused by thermal expansion and contraction, preventing cracks.

Driveway Compression

The pressure exerted on a home’s foundation when expanding concrete slabs, like driveways, push against it due to temperature changes.

Control Joint

Grooves placed in concrete to control where cracks occur, guiding them along predetermined lines.

Bowed Wall Repair

Wall Anchors

Steel plates connected by rods that are installed to stabilize and straighten bowed basement walls.

Carbon Fiber Straps

High-strength straps bonded to walls to reinforce and prevent further bowing without significant intrusion.

I-Beams

Steel beams installed vertically against walls to provide structural support and prevent inward movement.

Soil Pressure

The lateral force exerted by soil against basement walls, which can cause them to bow inward over time.

Foundation Wall Crack Repair

Epoxy Injection

A method of sealing cracks by injecting epoxy resin, restoring structural integrity.

Polyurethane Foam Injection

A flexible sealant injected into cracks to prevent water intrusion, accommodating slight movements.

Hydraulic Cement

A fast-setting cement used to patch leaks in concrete and masonry, expanding as it sets to create a tight seal.

Horizontal Cracks

Cracks running parallel to the ground, often indicating pressure from soil or water against the wall.

Glossary