BASEMENTATLAS · Problem scenarios
Basement problem scenarios – match what you actually see
Long-tail problem patterns built around timing, location and symptoms. Each scenario links to the technical guides and real cases most likely to help you investigate the cause.
Damp basement & water ingress
Basement still damp after new drainagechanges after rain, drain and sewer levels and existing and planned floor build-up→Basement floor wet but walls dryexisting and planned floor build-up, water pressure and groundwater and wall-to-floor junction→Basement wall gets wet after heavy rainchanges after rain, outside ground level and water pressure and groundwater→Salts return after painting the basement wallvisible salts/efflorescence, condition of the substrate and realistic drying time→Basement feels damp and cold but humidity readings look normaldew point and surface temperature, condition of the substrate and existing and planned floor build-up→Monitoring basement humidity – appears after new windowsdew point and surface temperature, actual air-change path and intended use of the room→Damp basement wall – only one corner is affectedchanges after rain, wall-to-floor junction and outside ground level→Water through the basement floor – starts after a new floor was installedchanges after rain, wall-to-floor junction and water pressure and groundwater→Water through the basement floor – appears around a pipe penetrationchanges after rain, wall-to-floor junction and water pressure and groundwater→Rainwater entering a basement – appears after very heavy rainchanges after rain, outside ground level and water pressure and groundwater→Groundwater below a basement floor – appears during snowmeltwater pressure and groundwater, existing and planned floor build-up and changes after rain→Monitoring basement humidity – gets worse when laundry dries indoorsdew point and surface temperature, actual air-change path and intended use of the room→Damp basement wall – remains even with a dehumidifierchanges after rain, wall-to-floor junction and outside ground level→Efflorescence and salts on basement walls – is concentrated at the bottom of the wallvisible salts/efflorescence, condition of the substrate and realistic drying time→Efflorescence and salts on basement walls – returns after cleaningvisible salts/efflorescence, condition of the substrate and realistic drying time→Damp basement wall – starts after a new floor was installedchanges after rain, wall-to-floor junction and outside ground level→Damp basement wall – appears around a pipe penetrationchanges after rain, wall-to-floor junction and outside ground level→Damp basement wall – appears during snowmeltchanges after rain, wall-to-floor junction and outside ground level→
Mould in basement & musty odour
Laundry smells musty after drying in the basementactual air-change path, hidden organic materials and intended use of the room→Cardboard or boxes mould on the basement floorexisting and planned floor build-up, dew point and surface temperature and hidden organic materials→Mould appears behind a new basement wallhidden organic materials, condition of the substrate and dew point and surface temperature→Mould in a basement – returns after cleaninghidden organic materials, condition of the substrate and dew point and surface temperature→Musty basement smell – is strongest when the house has been closedhidden organic materials, actual air-change path and dew point and surface temperature→Mould in a basement – only one corner is affectedhidden organic materials, condition of the substrate and dew point and surface temperature→Musty basement smell – gets worse when heating startshidden organic materials, actual air-change path and dew point and surface temperature→Mould behind a basement stud wall – starts after wall insulation was addedhidden organic materials, condition of the substrate and dew point and surface temperature→Mould in a basement – is concentrated near the ceilinghidden organic materials, condition of the substrate and dew point and surface temperature→
Basement ventilation & condensation
Basement humidity is high only in summerwarm/humid summer weather, dew point and surface temperature and actual air-change path→Ventilation makes the basement wetter in summerwarm/humid summer weather, dew point and surface temperature and actual air-change path→Dehumidifier runs almost all the time in the basementactual air-change path, dew point and surface temperature and changes after rain→Condensation forms on cold pipes in the basementdew point and surface temperature, condition of the substrate and actual air-change path→Basement indoor air quality – remains even with a dehumidifieractual air-change path, dew point and surface temperature and intended use of the room→
Basement drainage & exterior waterproofing
Underpinning & foundation strengthening
Radon in basement
Basement bathroom, drainage & waterproofing
Basement floor drain smellsrisk of sewer backflow, drain and sewer levels and future inspection and maintenance→Sewer backs up during heavy rainrisk of sewer backflow, changes after rain and drain and sewer levels→Basement sump pump – appears when the pump stopsdrain and sewer levels, risk of sewer backflow and future inspection and maintenance→Basement laundry rooms – gets worse when laundry dries indoorsactual air-change path, drain and sewer levels and intended use of the room→Sewer smell in a basement – is strongest when the house has been closedrisk of sewer backflow, drain and sewer levels and actual air-change path→Sump pump maintenance – appears when the pump stopsfuture inspection and maintenance, risk of sewer backflow and drain and sewer levels→
Basement windows, daylight & exterior exits
Water collecting in a basement window wellchanges after rain, outside ground level and drain and sewer levels→Condensation on basement windows – gets worse when heating startsdew point and surface temperature, condition of the substrate and actual air-change path→Condensation on basement windows – appears after new windowsdew point and surface temperature, condition of the substrate and actual air-change path→Basement window-well drainage – appears after very heavy rainoutside ground level, drain and sewer levels and water pressure and groundwater→
Basement walls, insulation & finishes
Paint peels mainly at the bottom of the basement wallcondition of the substrate, visible salts/efflorescence and water pressure and groundwater→Insulating basement walls – starts after wall insulation was addedcondition of the substrate, dew point and surface temperature and hidden organic materials→Thermal bridges in basements – is concentrated near the ceilingdew point and surface temperature, condition of the substrate and hidden organic materials→Peeling paint on basement walls – is concentrated at the bottom of the wallcondition of the substrate, visible salts/efflorescence and realistic drying time→