POSSIBLE CAUSES:
Salts originating from the bricks, concrete blocks, concrete, etc. are brought to the surface by water drying out
Excess moisture escaping through the exterior masonry walls from behind.
Active efflorescence is likely to push off any type of sealer or paint coating.
Ground salts contamination due to a broken / missing damp proof course.
SOLUTION:
If excess moisture is the cause, eliminate the source of the moisture.
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 stiff bristle brush.
Allow to completely dry out and continue brushing and removing the salts until they cease to appear. The substrate may be washed using a dilute vinegar solution in order to neutralise the alkalinity. Once dry, repaint with any of our Sandtex Trade Exterior Finishes.