A problem of painted masonry construction, efflorescence is identified by crusty white salt deposits bubbling through the paint film from an underlying masonry structure. It is caused by salts in the brick or concrete dissolving with water and then leaching to the surface as the water evaporates.
o Surface preparation was poor; prior efflorescence was not entirely removed and washed before the surface was repainted.
o Heavy moisture migrated through exterior masonry walls from inside the home.
o Inadequately waterproofed basement walls allowed groundwater penetration.
o Masonry was painted before the concrete or mortar had adequately cured and dried out.
o Cracks in the masonry wall or poor tuckpointing have allowed water to get behind masonry wall.
Repair and Prevention
o If moisture is getting into the masonry wall, eliminate the source of moisture by properly tuckpointing any cracks or missing mortar in the wall or patching concrete with a latex concrete patch; clean out gutters and downspouts, and caulk joints around windows and doors with a butyl rubber caulk.
o If moisture is migrating through the wall from the outside (e.g., basement wall), apply waterproofing to the outside of the wall.
o Remove all efflorescence and any loose flaking, chalking paint with a wire brush, scraping, or power washing. Then clean the area with a trisodium phosphate cleaning solution and rinse with clean water. Let completely dry, then paint with a high-quality latex house paint.