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My Basement Wall is White, Chalky, Powdery; Why?

Efflorescence describes crystalline salt deposits that appear on porous building surfaces. Salt efflorescence requires three elements: salt, water, and porous materials. Efflorescence is a chalky, white salt residue that can occur on any porous surface such as block basement wall, stone basement walls, and concrete.

Efflorescence can usually be found on a basement wall adjacent to a driveway, sidewalk, or attached garage. Concrete is a little like a sponge; capillary (wicking) action transport moisture through concrete.

When moisture carries salt to the surface, the air causes the water to evaporate, leaving a white crystalline type of powdery material or a chalky like substance on the surface called efflorescence.

What happens is water infiltrates the block or the stone wall and dissolves minerals. As water evaporates from the surface, the mineral deposits are left behind; thus, efflorescence crystals can grow. The salt pushes from the inside out and can eventually cause spalling (which is when the surface peels pop off or flakes off), or crumbling and deterioration.

Capillary attraction (wicking) an example of wicking (water contact) can be identified when a block may not leak but feel damp. Whenever a porous surface like concrete blocks or basement floors comes in contact with water, it soaks water up like a sponge.