Symptoms
- White, chalky, or crystalline coating on the basement wall
- Coating returns after brushing or washing it off
- Wall sometimes feels slightly damp to the touch
Likely causes
- CommonMoisture moving through the porous foundation wallWater from outside soil migrates through the wall and leaves minerals behind as it evaporates on the inside surface.
- CommonPoor exterior drainage or gradingThe same grading and gutter issues that cause damp basements typically drive this moisture movement.
- PossibleHigh groundwater or hydrostatic pressure in the areaIn some locations, groundwater itself pushes moisture through regardless of surface conditions.
What to do
- Brush off the deposit with a stiff brush or scrub with a diluted vinegar-water solution to clean the wall for closer inspection.
- Check exterior grading, gutters, and downspouts for issues directing water toward that section of foundation.
- Correct any drainage problems found outside, since efflorescence is a symptom of moisture movement, not the root cause itself.
- Monitor whether the white deposit returns after cleaning and after the next rain.
- Run a dehumidifier and improve basement ventilation to reduce overall dampness.
- Hold off on painting or sealing the wall until the exterior moisture source is addressed, since trapping moisture behind a coating can cause other problems.
- Have a waterproofing specialist evaluate if efflorescence is heavy or the wall feels consistently damp despite exterior fixes.
Tools and parts
- Stiff brush
- Bucket
Masonry waterproofing paintSearch: “masonry waterproofing paint”
When to call a pro
Call a waterproofing contractor if efflorescence is heavy, spreading, or paired with actual dampness or seepage.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.