Efflorescence on masonry
Salts leach from mortar as moisture dries out of it and can appear as a white dust or residue on the masonry. It naturally occurs from the drying out of new masonry and is not harmful to the house. These salts can be washed off with water or will disappear with weathering. However, if efflorescence persists at localized areas, this may indicate that a moisture problem may exist. Crumbling bricks at localized areas can also indicate a moisture problem.
The wetting of the masonry may be due to roof run-off, water splashing back off the ground, or moisture condensation occurring inside the walls. If you cannot find a remedy, contact your builder to diagnose and solve this problem.