Waterproofing Glossary
Essential terms and definitions for basement waterproofing in Ontario
Understanding Waterproofing Terms
Get familiar with the key terminology used in basement waterproofing to make informed decisions about your home's protection.
General
Basement Waterproofing
The process of applying materials and techniques to prevent water from penetrating the basement of a building, protecting the foundation and interior from water damage. This comprehensive approach may include interior drainage systems, exterior membrane applications, crack repairs, and sump pump installations.
Methods
Exterior Waterproofing
Waterproofing method applied to the outside of foundation walls, typically involving excavation around the perimeter, cleaning the foundation surface, applying waterproof membranes or coatings, and installing drainage systems to redirect water away from the structure.
Interior Waterproofing
Waterproofing solutions applied from inside the basement, including sealants, drainage systems, vapor barriers, and sump pumps to manage water intrusion. This method is often less invasive and more cost-effective than exterior waterproofing.
Negative Side Waterproofing
A waterproofing approach applied to the interior surface of a wall (the side opposite to where water pressure originates). Used when exterior access is limited or impossible, it manages water after it enters the wall structure.
Positive Side Waterproofing
Waterproofing applied to the exterior surface of a wall, directly facing the water source. This method prevents water from ever entering the wall structure and is considered the most effective long-term solution.
Blind Side Waterproofing
A waterproofing technique used in new construction when access to the exterior of the foundation wall is not possible after concrete is poured. The membrane is applied before concrete placement against an excavation support system.
Equipment
Sump Pump
A pump installed in a sump pit (basin) at the lowest point of a basement floor to remove accumulated water and discharge it away from the foundation. Essential component of interior drainage systems, available in submersible and pedestal configurations.
Backup Sump Pump
A secondary pump system that activates when the primary sump pump fails or becomes overwhelmed. Available as battery-powered, water-powered, or secondary electric units to ensure continuous protection during power outages or pump failures.
Sump Pit (Sump Basin)
A hole or container installed at the lowest point of a basement floor to collect water from drainage systems. The sump pump is placed inside this pit to remove accumulated water and discharge it away from the building.
Backwater Valve (Backflow Preventer)
A valve installed in the sewer line to prevent sewage from backing up into the basement during heavy rainfall or sewer system overload. Many Ontario municipalities offer rebates for installation.
Dehumidifier
A device that removes excess moisture from the air, helping to maintain optimal humidity levels (30-50%) in basements and prevent mold growth. Essential for ongoing moisture control in many Ontario basements.
Hygrometer
An instrument that measures the relative humidity in the air. Used to monitor basement moisture levels and ensure they remain in the safe range to prevent mold growth and material damage.
Drainage
French Drain
A drainage system consisting of a perforated pipe surrounded by gravel or aggregate, designed to redirect surface water and groundwater away from foundations. Can be installed around exterior foundation perimeter or along interior basement walls.
Weeping Tile
Perforated drainage pipes installed around the foundation perimeter at or below footing level to collect and redirect groundwater away from the building. The term originated from clay tiles but now typically refers to plastic perforated pipes.
Interior Drain Tile
A perimeter drainage system installed inside the basement along the foundation walls. Water seeping through walls or floor is collected in channels and directed to a sump pump for removal.
Catch Basin
A drainage structure designed to collect surface water runoff and direct it into the underground drainage system. Often placed at low points in yards, driveways, or near downspout discharge points.
Dry Well
An underground structure that collects and disperses stormwater runoff into the surrounding soil. Used to manage water from sump pumps, downspouts, or surface drainage when connection to storm sewers is not available.
Downspout Extension
A pipe or trough that carries rainwater from gutter downspouts away from the foundation. Should extend at least 6 feet from the building or connect to an underground drainage system.
Technical
Hydrostatic Pressure
The pressure exerted by water against foundation walls and floor due to groundwater buildup in the surrounding soil. This pressure increases with depth and water table height, often causing basement leaks, cracks, and structural issues.
Water Table
The underground level at which the soil or rock is completely saturated with water. High water tables, especially during spring thaw or heavy rainfall, increase hydrostatic pressure against foundations and the risk of basement flooding.
Capillary Action
The ability of water to move through porous materials (like concrete) against gravity through tiny pores and cracks. This phenomenon can draw moisture up through concrete floors and walls, causing dampness even without visible cracks.
Permeability
The ability of a material to allow water or moisture to pass through it. Concrete, despite appearing solid, is porous and permeable to varying degrees depending on its composition and age.
Problems
Foundation Crack
Cracks in foundation walls or floors that can allow water infiltration, ranging from hairline cracks to structural damage requiring professional repair. Types include shrinkage cracks, settlement cracks, and structural cracks.
Shrinkage Crack
Hairline cracks that develop in concrete as it cures and loses moisture. Common and usually not structurally significant, but can allow water infiltration and should be sealed to prevent moisture problems.
Settlement Crack
Cracks that develop when a foundation settles unevenly due to soil conditions, improper compaction, or changes in soil moisture. Often diagonal and may indicate ongoing structural movement requiring professional assessment.
Efflorescence
White, chalky mineral deposits left on masonry surfaces when water evaporates, indicating moisture movement through the concrete or block. While not harmful itself, it signals moisture problems that should be addressed.
Spalling
The flaking, peeling, or breaking away of the surface layer of concrete due to freeze-thaw cycles, corrosion of reinforcing steel, or moisture penetration. Indicates deterioration requiring repair to prevent further damage.
Basement Flooding
Water accumulation in basements due to heavy rainfall, plumbing failures, sewer backups, or inadequate waterproofing. Can cause extensive property damage and mold growth if not addressed promptly.
Materials
Waterproof Membrane
A protective barrier applied to foundation walls to prevent water penetration, available in liquid-applied, sheet, or spray-on forms. Materials include rubberized asphalt, polyurethane, bentonite clay, and thermoplastic sheets.
Vapor Barrier
A material used to prevent moisture vapor from passing through walls, floors, and ceilings, helping control humidity in basements and crawl spaces. Typically 6-mil or thicker polyethylene sheeting installed on the warm side of insulation.
Bentonite Clay
A natural clay material that swells when wet, creating a waterproof barrier. Used in sheet form or as panels for exterior foundation waterproofing, particularly effective because it self-heals small punctures.
Crystalline Waterproofing
A waterproofing technology that uses chemicals which react with water and concrete to form crystals that fill pores and cracks. The crystals reactivate when exposed to water, providing ongoing self-healing protection.
Drainage Board (Dimple Board)
Plastic sheets with dimpled surfaces installed against exterior foundation walls to create an air gap and drainage channel. Protects waterproofing membranes and directs water to the drainage system.
Hydraulic Cement
A fast-setting cement that can be applied to wet surfaces and will set even underwater. Commonly used for emergency basement leak repairs and sealing active water infiltration points.
Penetrating Sealer
A waterproofing product that soaks into concrete pores rather than forming a surface film. Protects against moisture intrusion while allowing the concrete to breathe and release trapped moisture.
Repair
Parging
A thin coat of cement-based mortar applied to foundation walls to provide a smooth surface and additional protection against moisture. Often used on block foundations and as part of exterior waterproofing systems.
Crack Injection
A repair method using polyurethane or epoxy materials injected under pressure into foundation cracks to seal them and prevent water entry. Polyurethane expands and remains flexible, while epoxy provides structural bonding.
Epoxy Injection
A structural crack repair method using high-strength epoxy resin injected into cracks to restore the concrete to its original strength. Best for non-moving cracks where structural integrity is a concern.
Polyurethane Injection
A crack sealing method using expanding polyurethane foam injected into cracks. The foam expands to fill the entire crack and remains flexible to accommodate minor foundation movement.
Carbon Fiber Reinforcement
High-strength carbon fiber straps or sheets bonded to foundation walls to stabilize and prevent further movement of bowing or cracking walls. Provides structural support without the need for excavation.
Health
Mold Remediation
The process of identifying, containing, removing, and preventing mold growth in buildings. Often necessary after water damage or persistent moisture problems, and should be performed by certified professionals for large infestations.
Structural
Window Well
A recessed area around basement windows that allows natural light and emergency egress. Requires proper drainage and waterproofing to prevent water accumulation and infiltration.
Window Well Cover
A protective cover installed over window wells to keep out rain, snow, leaves, and debris while allowing light to enter. Available in clear plastic or metal grate designs.
Cold Joint
The junction where the basement floor meets the foundation wall, created when concrete is poured at different times. A common entry point for water that often requires special attention during waterproofing.
Foundation Footing
The concrete base that supports the foundation walls and distributes the building load to the surrounding soil. Drainage systems are typically installed at or below footing level for effective water management.
Cove Joint
Another term for the cold joint where the basement floor meets the wall. Interior drainage systems often include a cove joint drainage channel to capture water entering at this common weak point.
Construction
Backfill
Material used to fill excavated areas around foundations after waterproofing work is completed. Proper backfill selection and compaction are critical for drainage and foundation stability.
Grading
The slope of the ground surface around a building. Proper grading (minimum 6 inches drop in 10 feet) directs surface water away from foundations to prevent water accumulation and infiltration.
Need Professional Help?
Understanding these terms is the first step, but professional waterproofing requires expertise and experience. Find qualified contractors in your area through our directory.
Resources & guides
Practical articles on waterproofing, foundations, and moisture—written for Ontario homeowners.