Excessive and heavy powdering. Paints chalk naturally somewhat over long exposure to sun and weather.
CHALKING PROBABLE CAUSES
Usually due to natural weathering. Paints using excessive clay in place of titanium dioxide. Interior paints being used for exterior surfaces. Over-thinning or spreading too thinly. Wrong product selection.
Remove all of the chalk dust with a stiff bristle brush (wire on masonry) and rinse thoroughly with a garden hose with high water pressure. For best and quickest results, use a power washer. If some chalk residue remains, a chalk binder coat is required
PRIMERS & INTERIOR FINISHES
Priming is essential for better adhesion, sheen uniformity, mildew control and durability. Select a top quality interior paint in the color and sheen of your choice.