Basement Terminology

Below is a list of terms commonly used in basement waterproofing, foundation repair and basement finishing.  Please browse through the terminology below, and if you have any questions about basements, as always we encourage you to call us directly at 416-633-7180.  We love to help.

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Acidic Soil

Soil pH is a measurement of the alkalinity or acidity of soil.  pH is measured on a scale of 1 – 14, with 7 as the neutral mark, anything below 7 considered acidic and anything above 7 considered alkaline.



Refers to the attraction between two molecules, each having regions of low level positive and negative charge.


Airborne Particulates

A term that refers to dust, debris and other elements throughout the air in a home. Due to the upward movement of warm air in a home, a vacuum is created in the lower levels. If a basement or crawl space is infested with mold or other unpleasant airborne pollutants and allergens, they are then pulled upwards into the home along with the air.


Air-gap Membrane

A dimpled membrane, typically manufactured using a high density polyethylene, impermeable to water and water vapour, that creates an air gap between the membrane and a foundation wall. Water between the air-gap membrane and the foundation wall flows freely towards the weeping tile. It also provides a capillary break between the foundation wall and the saturated soil surrounding it.


Air Mop

The replacement of excavated earth into a trench around or against a basement or crawlspace foundation wall.



Basement Floor Slab

The 4 or 5 inch layer of concrete that forms the basement floor.


Bowed Wall

When outside pressure exceeds the design capacity of a well resulting in a bow or curve.


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Capillary Break

A barrier that prevents the flow of moisture through the small interconnected pores in concrete due to adhesion and surface tension.  Also referred to as “wicking”.


Carbon Fibre

A reinforced polymer that is characteristically very strong, light and a composite material known for its high strength to weight ratio. Carbon Fibre will not stretch or bend over time making it perfect for reinforcing concrete walls.


Carbon Fibre Kevlar Weave

This carbon fibre product has a Kevlar weave that produces some horizontal strength. A necktie is attached to the sill plate, which can disperse the outside force.


Carbon Fibre Plates or Sheets

Carbon fibre plates that are pre-impregnated with an epoxy resin. The plates do not secure to the sill plate or floor where the major problem areas occur.


Carbon Fibre Staples

Carbon Staples can be used as a crack control stitching system designed to transfer load away from repair materials.



To install or apply a sealant across or into joints, cracks, or crevices to prevent the passage of air or water.


Cinder Block

A pre-fabricated structural component constructed of concrete and cinders that is utilized to construct foundation walls, retaining walls, etc.


Clay Backfill

The replacement of excavated earth containing clay around a basement foundation wall. Clay backfill can result in poor surface and subsurface drainage leading to water ponding around the house, leakage of ground water through the basement or crawlspace walls, and structural damage to the foundation.


Clay Bowl Effect

Backfill soil that’s been removed as the foundation is dug is looser, more porous and much more absorbent of water than the un-excavated soil around it. As the soil around the house settles, it begins to dip lower than the un-excavated soil. As the water runs downhill into this depression, it pools and absorbs into the dirt around the foundation. In areas where the soil contains clay, this is called the “Clay Bowl” effect which allows water to seep anywhere it can go resulting in pressure on basement walls. This pressure can create cracks that can allow water to come through.


Clay Soil

Soil, which is composed of very fine particles, usually silicates of aluminum and/or iron and magnesium. Clay soil impedes the flow of water, meaning it absorbs water slowly and then retains it for a long time. Wet clay soil is heavy and sticky, and tends to swell from the added moisture. When dry, clay soil shrinks and settles. The top layer can bake into a hard, concrete-like crust, which cracks.


Clean Space

An unplanned joint or discontinuity in poured concrete structures resulting from a delay in placement of sufficient time to preclude a chemical union of the material in two successive pours.


Cold Joint

A cold joint is the intersection between the end of one concrete pour and the beginning of a new pour. The basic rule is to try to avoid cold joints by pouring straight through until the job is finished. The cold joint is a weak area and could allow the entry of water.


Concrete Block

Large, rectangular blocks used in construction usually made from sand and fine gravel. The use of block work allows structures to be built in the traditional masonry style with layers (or courses) of overlapping blocks. Canadian homes are typically built with a concrete foundation and slab with a concrete block wall on the perimeter.


Control Joint

A formed, sawed, or tooled groove in a repair surface to create a weakened plane and regulate the location of cracking resulting from restrained contraction of the material. Such provisions are also termed control relief joints. Adequately designed and constructed, these joints serve to eliminate random surface cracks by gathering, distributing and dissipating stress forces resulting from temperature and moisture variations.


Cove Base

A one inch carbon fibre strap used to repair concrete wall cracks. Characteristically, the long and noticeable vertical crack is accompanied by several small horizontal cracks that are not strengthened by the traditional method of a crack injection. The result is two weak spots on each side of the vertical crack. The crack strap method is installed by drilling holes on each side of the vertical crack and securing the one inch carbon fibre straps along the duration of the crack. This method leaves the sides weakened by the initial crack stronger than they ever were before.


Crawl Space

A crawl space (as the name suggests) is a type of basement in which one cannot stand up — the height may be as little as a foot, and the surface is often soil. They offer access to pipes, substructures and a variety of other areas that may be difficult or expensive to access otherwise. While a crawl space cannot be used as living space, it can be used as storage, often for infrequently used items. Health and convenience issues accompany a crawl space as water from the damp ground, water vapour (entering from crawl space vents), and moisture seeping through porous concrete can create a perfect environment for mold/mildew to form on any surface in the crawl space, especially cardboard boxes, wood floors and surfaces, drywall and some types of insulation.


The Crawl Space Conduit

The process of encapsulating the crawl space with a vapour barrier and insulation creating a clean, healthy and usable space.


Crawl Space Drain Matt

Treatment of a surface or installation of a technology to resist the passage of moisture caused by differences in moisture content, vapour pressure and temperature across the basement envelope to prevent accumulation of water against the outer surfaces of the envelope (walls and floor slab).


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A household appliance that reduces the level of humidity in the air.



With respect to concrete block foundations, involves the removal or draining of water that has accumulated within concrete blocks.


Dig & Push

A method in repairing a bowed foundation wall by excavating soil against the wall from the outside and applying pressure to push the wall back to a straight position. The area outside is then backfilled with gravel.



A vertical pipe used to drain rainwater from a roof.


Drainage Matting

A perforated, corrugated plastic pipe laid at the bottom of the foundation wall and used to drain excess water away from the foundation. It prevents ground water from seeping through the foundation wall. Sometimes called perimeter drain.


Dry Lock

Vapour Barrier for Basements, Attics and Crawl Spaces.


Dry Well

A dry well is an underground excavated area filled with stone that disposes of water, most commonly drainage runoff, by dissipating it into the ground, where it merges with the local groundwater. A hole in the ground filled with gravel or rubble to receive drainage water and allow it to percolate away.


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A deposit of white salts left on a surface when a solution containing the salts leaches from concrete or masonry and then evaporates.


Egress Windows

Code compliant and fire-escapable windows created for basements.


Epoxy Injection

A method of sealing or repairing cracks in poured concrete by injecting epoxy adhesives into the cracks in order to fill them.



The wearing away of land or soil by the action of wind, water, or ice.


Evaporative Moisture Cooling

A phenomenon whereby moisture that evaporates imparts a cooling effect upon the material that is damp or wet.



To dig out and remove soil.


Exterior Footing Drain

A tube or cylinder or box that is normally installed around the exterior perimeter of the foundation footings that collects and directs ground water away from the foundation of the house.


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Floor Crack

Masonry failures due to vertical shear.


Floor Drain Backwater Valve

A check valve that prevents the back-flow of water from the municipal storm sewer system to your basement floor drain.


Floor Joists

Horizontal supporting members that run from wall to wall, wall to beam, or beam to beam to support a floor. It may be made of wood, steel, or concrete.



A footing is a poured concrete structure embedded below the frost line, and is typically twice the width of the wall that it supports. The footing transfers the weight of the foundation walls to the soil or bedrock beneath it.



The lowest and supporting part or member of a wall, including the base course and footing courses; in a frame house, the whole substructure of masonry.


French Drain

A French drain, drain tile, perimeter drain or land drain is a ditch covered with gravel or rock that redirects surface and ground water away from an area. A French drain can have hollow pipes along the bottom to quickly disperse water that seeps down through the upper gravel or rock. French drains are common drainage systems, commonly used to prevent ground and surface water from travelling towards the foundation.


Frost Line

Also referred to as frost depth or freezing depth — is most commonly the depth to which the groundwater in soil is expected to freeze. The frost depth depends on the climatic conditions of a given geographic area, the heat transfer properties of the soil and adjacent materials, and on nearby heat sources.


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Glass Brick Windows

An architectural element made from glass. Glass bricks provide visual obscuration while admitting light. Commonly used in basements for privacy and security.



This typically refers to the pitch of a slope such as a hill, road or railway; with respect to waterproofing, it is the height of the soil, or other surface, surrounding the foundation.


Gravity Feed

The movement of materials from one location to another by force of gravity.


Ground Water

Is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. Groundwater is water that has drained through surface layers of soil and rock until it reaches a layer of rock material through which it cannot pass, or can pass only very slowly. This results in the accumulation of water in the rock layers above this impermeable layer. The water is stored in gaps in the rock, or between the particles of which the rock is composed.


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Hairline Crack

A crack in an exposed concrete surface that is barely visible because of its extremely narrow width.



Refers to voids in concrete caused by the mortar not filling the spaces between the coarse aggregate particles.



Refers to “a fear of water”. In referring to the properties of polyurethane and epoxy resins, the hydrophobic resin molecules cluster together upon exposure to water; similar to how cooking oils tend to cluster together even after they are dispersed.


Hydrostatic Pressure

The force that is exerted on an underground structure by the water that is in the ground surrounding the structure.


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Ice Guard

A fitting that goes on your sump pump discharge line. It helps to prevent ice backing up causing a basement to flood.


Infrared Thermography

A non-destructive testing method for locating de-lamination in pavements and bridge decks and detecting moist insulation, concrete, and wood in buildings; the presence of flaws within concrete affects the heat conduction properties of the concrete and the presence of defects is indicated by differences in surface temperatures when the test object is exposed to correct ambient conditions. In the waterproofing industry it is typically used to detect moisture behind closed walls by detecting evaporative moisture cooling.


Interior Perimeter Drain

Refers to the installation of a perimeter drain pipe, that functions in a similar way to weeping tile, along the inside perimeter of the basement walls beneath the floor slab.


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A joint between the footing and foundation wall.


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A layer of material, typically impermeable, used as a lining on outdoor concrete walls.



Usually white in appearance, is the superficial growth of fungi on organic materials, such as wood. A plant disease where the pathogen occurs as a growth on the host’s surface.


Mold (Mould)

The growth of minute fungi that form on organic matter, often the result of decay due to exposure to moisture/dampness. Parasitic, microscopic fungi with spores that float in the air like pollen. Mold is a common trigger for allergies and can be found in damp areas, such as the basement or bathroom.


Mortar Joint

A brick being secured to another similar brick or bricks by means of mortar or grout.


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Columns of concrete usually poured into drilled holes in the ground, on which the concrete slab will rest. This ensures that the slab is ultimately resting on the ground sufficiently solid to support the weight of the home.



Columns of concrete usually poured into drilled holes in the ground, on which the concrete slab will rest. This ensures that the slab is ultimately resting on the ground sufficiently solid to support the weight of the home.



A thermoplastic polymer used in a wide variety of applications.


Polyurethane Injection

A method for sealing or repairing cracks in concrete by injecting polyurethane resin.


Positive Side Waterproofing

Applying waterproofing material to the side of a structural element subjected to hydrostatic pressure (always the outside wall surface).


Poured Concrete

Any concrete structure or slab that was poured and formed in a liquid state.


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Radon Gas

A colourless, odourless, radioactive gas that occurs naturally as a result of the decay of radium. It is found to varying degrees as a component of soil gas and is known to enter dwelling units by infiltration into crawl spaces and basements. The presence of the decay products of radon in sufficient quantity can lead to increased risk of lung cancer.


Reentrant Cracks

Cracks at the corner of windows and other openings that are usually the result of stress build-up at the corner(s).


Relative Humidity

Humidity is typically measured as relative humidity (RH). RH is a percentage value that indicates the amount of moisture in the air relative to the maximum amount the air can hold at a given temperature. Cold air is able to hold less moisture than warm air; hence, the air is dry during the winter and humid in the summer.


Return On Investment (ROI)

A performance measure used to evaluate the efficiency of an investment or to compare the efficiency of a number of different investments. In terms of real estate ROI, refinishing a basement instantly and easily adds a significant amount of living space with even a simple basement remodel.


Rim Joist

Also referred to as a band joist. A rim joist rests on the sill or sill plate functioning to keep the joists true also providing a surface for completing the edge of sub-flooring and a flat base to support the exterior walls. The rim joist is the “box” of a floor’s structure.



Iron oxide that forms when exposed to oxygen and moisture.


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Sill Plate

A sill plate, or sole plate, in construction is the bottom horizontal member of a wall or building to which vertical members are attached. In the platform framing method the sill plate is anchored to the foundation wall. The bottom of the sill plate is ideally kept 6 inches above the finished grade.



Substrate particles smaller than sand and larger than clay.



A solid concrete structure. Typically, slabs are installed as ceilings over cold cellars as well as over a gravel base for the construction of basement and garage floors.



Refers to the wetness of concrete when delivered, slump is measured on a scale of 1 to 12 with 1 being the driest mix.


Snap Rod

A rod which is used to hold concrete forms in place when building a poured concrete foundation. It is called a snap rod because, once the concrete has cured and the forms have been removed, the protruding rods are snapped off (usually with a hammer); thus providing a smooth concrete surface.


Soil Expansion

Expansive soils contain minerals such as smectite clays that are capable of absorbing water. When they absorb water they increase in volume. The more water they absorb the more their volume increases. Expansions of ten percent or more are not uncommon. This change in volume can exert enough force on a building or other structure to cause damage.



The chipping, splintering, and breaking into smaller pieces of poured concrete, concrete blocks or cinderblocks, bricks, and stone. Spalling usually occurs when water that has permeated porous materials freezes and causes surface deterioration.



To produce or release spores.


Stack Effect

A term that refers to the way air moves throughout a home. Due to the upward movement of warm air in a home, a vacuum is created in the lower levels. If a basement or crawl space is infested with mold or other unpleasant airborne pollutants and allergens, they are then pulled upwards into the home along with the air.


Stationary Beams

The most common type of wall support on the market the uses a 13 lb steel H beam concreted into the floor and framed into the floor joists above.


Sump Pump

A sump pump is a pump used to remove water that has accumulated in a sump pit. A sump pit, commonly found in the home basement, is simply a hole to collect water. A pump used to mechanically evacuate water that has accumulated in a sump pit or liner, usually found beneath the floor in the basement of homes. The water may enter the sump pit via the perimeter drains of a basement waterproofing system such as weeping tile or an internal de-watering system, or if the basement is below the level of the local water table. Sump pumps are also used where basement flooding happens regularly and to protect against dampness where the water table is high relative to the footing of a home. Sump pumps mechanically pump water away from a house to any place where it is no longer problematic, such as a municipal storm drain or a dry well, or to the outside. In older homes, sump pumps may be connected to the sanitary sewer.


Currently, this practice is not in conformance with the plumbing code and/or municipal bylaws because the volume of water coming from sump pits can overwhelm the municipal storm drain system. Powered by a home’s electrical system, sump pumps can be supplemented by a battery backup. Since a sump pit may overflow if not constantly pumped, a backup system is important for cases when the main power is out for prolonged periods of time, also, the sump pump can corrode from evaporating water in the sump pit; if a motor does not operate frequently, it is advisable to cause the motor to run at least every 3 months. There are two types of sump pumps: pedestal and submersible. The pedestal pump’s motor is mounted above the pit, where it is more easily serviced but also more conspicuous. The submersible pump is entirely mounted inside the pit, and is specially sealed to prevent electrical short circuits.


Surface Repair

Repair of a concrete surface that constitutes only a small portion of the depth of a member or element.


Surface Tension

A phenomenon caused by the attraction of molecules to like molecules. As molecules on the liquid surface are not surrounded by the same molecules on all sides, there is a resultant increase in their attraction to neighbouring molecules on a surface.



A shallow trough-like depression that carries water mainly during rainstorms or snow melts.


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Tank Pro

A viscous black liquid containing numerous organic compounds that is obtained by the destructive distillation of coal and used for roofing and waterproofing.


Tuck Pointing

Also referred to as “repointing”, involves the placement of wet mortar into cut or raked joints for the repair of weathered joints in old or damaged masonry. Repointing: See Tuck pointing.


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To dig or wear away the base or foundation.



A solid foundation laid below ground level to support or strengthen a building.


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Vapor Barrier

A barrier used to prevent water vapor diffusion; a vapor barrier is typically used to isolate wooden or steel framing from the concrete on which it rests.


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Wall Crack

A thin and usually jagged space opened in a previously solid material.


Water Guard

Drain tile designed to make waterproofing less labor intensive. The water guard sits level to the footer, therefore in order for water to flow, it must constantly have water in it. Most versions have an open back creating mold and mildew issues.


Water Leak

To let water or other fluid in or out through a hole, crevice, etc.


Wall Replacement

If the inward bowing of a basement wall is not excessive, walls damaged by excessive inward pressures may often be repaired by excavating behind the wall, allowing the wall to flex back into vertical position. If the inward bowing of the wall is excessive, the wall requires replacement. The foundation drainage system will also require replacement at that time. The details for these repairs may be determined by a qualified and experienced contractor or a structural engineer.


Water Seepage

Water oozed through a porous material or soil. The act or process of seeping; percolation.


Wall Shearing

Movement of a basement wall due to outside pressure that eventually cause the bottom of the wall to slide over the foundation floor. This is most common in concrete block walls.


Water Table

The level below which the ground is completely saturated with water. Also called water level. It is also known to be the depth at which soil pore spaces or fractures and voids in rock become completely saturated with water.


Wall Tie Backs

A solution for repairing bowed walls using an interior wall plate, an exterior earth anchor and a connecting steel rod to stabilize foundation walls.


Water Table

The level below which the ground is completely saturated with water. Also called water level. It is also known to be the depth at which soil pore spaces or fractures and voids in rock become completely saturated with water.


Weeping Tile

A porous or perforated pipe used for underground drainage. Weeping tile is installed along the foundation footings exposed to the water table.



The flow of moisture through the small interconnected pores in concrete due to adhesion and surface tension.


Window Well

Typically a galvanized steel semi-circular structure installed to prevent the cave-in of soil and water flow into below grade basement windows.


Window Well Drain

A drain, similar to a kitchen sink drain, which channels window well water towards the weeping tile and its surrounding gravel layer. A window well drain prevents water from entering a basement from around the window frame or through the window itself.


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