Crusty, white salt deposits, leached from mortar or masonry as water passes through it.
- Failure to adequately prepare surface by removing all previous efflorescence.
- Excess moisture escaping through the exterior masonry walls from behind.
- If excess moisture is the cause, eliminate the source by repairing the roof, cleaning out gutters and downspouts, and sealing any cracks in the masonry with a high quality, water-based all-acrylic or siliconized acrylic caulk.
- If moist air is originating inside the building, consider installing vents or exhaust fans, especially in kitchen, bathroom and laundry areas.
- Remove the efflorescence and all other loose material with a wire brush, power brush or power washer; then thoroughly rinse the surface.
- Apply a quality water-based or solvent-based masonry sealer or primer, and allow it to dry completely; then apply a coat of top quality exterior house paint, masonry paint or elastomeric wall coating.
Note: Images & information provided by The Rohm & Hass Paint Quality Institute.