Efflorescence
 
Cause

Efflorescence is often seen as a white fluffy deposit of salt crystals on cementitious wall surfaces. It depends on the presence of salt and moisture. The growth of crystals will continue as long as both are present. The salts are present in the mortar blocks or concrete structure and the moisture is usually attributable to some building defect. When emanating from mortar in brick or block buildings, efflorescence will appear as narrow bands corresponding to mortar joints.
 
Solution

Painting should be delayed if efflorescence continues. Salts should be removed by mechanical brushing. The use of water to remove efflorescence will only aggravate the defect. Repair areas where moisture penetrates the wall. Allow walls to dry thoroughly.

1Caulk all areas such as nail heads, holes and butt joints.
 

Recommendations: