White stuff on your brick: what efflorescence means
That white, powdery haze on brick is called efflorescence. The stain itself is harmless, but it means water is moving through the masonry, and that's worth paying attention to.
What it is
Brick, mortar and concrete contain natural salts. When water soaks in, it dissolves those salts and carries them to the surface. The water evaporates, and the salt stays behind as a white film.
Is it a problem?
The white film won't hurt the wall. The water behind it can. When salts dry just under the surface instead of on it, they can push the face off the brick, which is called spalling. Freeze-thaw does the same thing to wet brick in winter.
New brick vs. old brick
New masonry often shows some efflorescence in its first year as construction moisture dries out, and it usually fades. If it keeps coming back on older brick, something is letting water in.
Common causes
- Open or worn mortar joints
- A cracked chimney crown or missing cap
- Overflowing gutters or downspouts dumping water against the wall
- Sprinklers hitting the brick
- Soil or mulch piled against the brick
- Missing or damaged flashing
How to clean it
Start with a stiff dry brush on a dry day. Light efflorescence often brushes right off. For heavier staining, use water and a masonry cleaner made for efflorescence. Skip high-pressure washing and strong acids. They can damage the brick face and the joints and make things worse.
When to call
If the white keeps coming back, or you see flaking brick or crumbling joints along with it, have the source checked. Fixing where the water gets in matters more than the cleaning.
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