Capillary-breaking layer
Granular or other designed layer intended to reduce capillary transport of ground moisture toward the floor construction.
→BASEMENTATLAS · Basement glossary
Basement terminology – practical glossary
Common basement construction, moisture and renovation terms explained in plain language.
Underpinning
Structural work that extends or strengthens an existing foundation, often needed when excavating below its original level.
→Hydrostatic pressure
Pressure created by water against a below-ground construction; relevant when water level can rise outside a wall or below a floor.
→Dew point
Temperature at which air becomes saturated and water vapour can condense on a surface.
→Relative humidity
Moisture in air expressed relative to the maximum the air can hold at the same temperature.
→Perimeter drain
Drainage system around the exterior of a below-ground foundation intended to manage water in the soil.
→Basement lightwell
Recess outside a below-ground window that allows daylight and access to the window while keeping surrounding soil back.
→Sump pump
Pump system used when water or wastewater must be lifted to a higher discharge level.
→Sewer backflow
Condition where wastewater rises back toward low fixtures because the downstream sewer level or pressure becomes too high.
→Radon membrane
Air-tight layer intended to limit soil gas entering through the floor construction; joints and penetrations are critical details.
→Capillary-active wall system
Mineral internal wall build-up designed to transport and redistribute moisture rather than trapping it behind an organic lining.
→Thermal bridge
Part of the construction with higher heat flow, often creating a colder internal surface and therefore higher local relative humidity.
→Efflorescence and salts on basement walls
Efflorescence and salts on basement walls. Start by documenting visible salts/efflorescence, condition of the substrate and realistic drying time. The purpose is to understand the building condition and constraints before choosing products, finishes or a work sequence.
→Vapour and air barriers below basement floors
Vapour and air barriers below basement floors. Start by checking existing and planned floor build-up, pipe and cable penetrations and water pressure and groundwater. These details help separate the visible symptom from the construction condition before a repair method is selected.
→Insulating basement walls
Insulating basement walls. Start by documenting condition of the substrate, dew point and surface temperature and hidden organic materials. The purpose is to understand the building condition and constraints before choosing products, finishes or a work sequence.
→Drainage gravel and filter fabric
Drainage gravel and filter fabric. Start by checking drain and sewer levels, future inspection and maintenance and water pressure and groundwater. These details help separate the visible symptom from the construction condition before a repair method is selected.
→Dimpled membrane on basement walls
Dimpled membrane on basement walls. Check outside ground level, drain and sewer levels and condition of the substrate before deciding what to repair. These observations help separate a surface symptom from water, air, drainage or construction conditions.
→Drainage gravel and filter fabric
Drainage gravel and filter fabric. Start by checking drain and sewer levels, future inspection and maintenance and water pressure and groundwater. These details help separate the visible symptom from the construction condition before a repair method is selected.
→Backwater valves in basements
Backwater valves in basements. Start by documenting risk of sewer backflow, drain and sewer levels and future inspection and maintenance. The purpose is to understand the building condition and constraints before choosing products, finishes or a work sequence.
→Basement floor drains
Basement floor drains. Start by documenting drain and sewer levels, risk of sewer backflow and existing and planned floor build-up. The purpose is to understand the building condition and constraints before choosing products, finishes or a work sequence.
→Heat-recovery ventilation in basements
Heat-recovery ventilation in basements. Check actual air-change path, dew point and surface temperature and intended use of the room before deciding what to repair. These observations help separate a surface symptom from water, air, drainage or construction conditions.
→Monitoring basement humidity
Monitoring basement humidity. Start by documenting dew point and surface temperature, actual air-change path and intended use of the room. The purpose is to understand the building condition and constraints before choosing products, finishes or a work sequence.
→Groundwater below a basement floor
Groundwater below a basement floor. Start by checking water pressure and groundwater, existing and planned floor build-up and changes after rain. These details help separate the visible symptom from the construction condition before a repair method is selected.
→Rising damp in basement walls
Rising damp in basement walls. Start by checking visible salts/efflorescence, condition of the substrate and wall-to-floor junction. These details help separate the visible symptom from the construction condition before a repair method is selected.
→Waterproof slurry inside a basement
Waterproof slurry inside a basement. Check condition of the substrate, water pressure and groundwater and pipe and cable penetrations before deciding what to repair. These observations help separate a surface symptom from water, air, drainage or construction conditions.
→Basement window-well drainage
Basement window-well drainage. Check outside ground level, drain and sewer levels and water pressure and groundwater before deciding what to repair. These observations help separate a surface symptom from water, air, drainage or construction conditions.
→Underfloor heating in a basement
Underfloor heating in a basement. Start by documenting existing and planned floor build-up, existing foundation depth and intended use of the room. The purpose is to understand the building condition and constraints before choosing products, finishes or a work sequence.
→Drying concrete and screed in basements
Drying concrete and screed in basements. Start by checking realistic drying time, existing and planned floor build-up and condition of the substrate. These details help separate the visible symptom from the construction condition before a repair method is selected.
→Lime plaster in basements
Lime plaster in basements. Check condition of the substrate, visible salts/efflorescence and realistic drying time before deciding what to repair. These observations help separate a surface symptom from water, air, drainage or construction conditions.
→Silicate paint for basement walls
Silicate paint for basement walls. Check condition of the substrate, visible salts/efflorescence and realistic drying time before deciding what to repair. These observations help separate a surface symptom from water, air, drainage or construction conditions.
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