Central Mississippi

What is That White Powdery Stuff on My Brick Wall?

Efflorescence—the fine, white, powdery deposit on masonry surfaces—can be a minor eyesore or a warning of deeper structural issues. Derived from the French term meaning “to flower out,” efflorescence occurs when water-soluble salts in masonry dissolve, migrate to the surface, and are left behind as water evaporates. While often just cosmetic (primary efflorescence), it can signal serious structural weaknesses (secondary efflorescence) if ignored.

Why It Happens: The Three Must-Haves

Efflorescence requires three conditions to form. Miss one, and it won’t appear:

  1. Water-soluble salts must be present in the masonry.
  2. Moisture must be sufficient to dissolve these salts.
  3. A pathway must allow the salt solution to migrate to the surface.

Typically, efflorescence shows up a month to a year after construction, often catching builders and homeowners off guard.

Prevention: Build Smart, Stay Dry

Elevation of Church - Gary Smith - Home Inspector

Preventing efflorescence starts with thoughtful design and quality materials:

  • Use low-alkali Portland cement to minimize salt content.
  • Choose clean, washed sand for mortar and grout to avoid high-alkali sulfates.
  • Mix with potable water free of salts.
  • Design for water exclusion: Incorporate overhanging eaves, copings, flashings, and strategic landscaping to keep water out.
  • Opt for tooled mortar joints (concave or V-shaped) to reduce water intrusion.

Removal: Handle with Care

Removing efflorescence requires finesse to avoid damaging the masonry:

  • Dry brushing is a gentle first step, but avoid sandblasting, which can erode brick and mortar, inviting more water ingress.
  • Chemical washing with a mild solution of one part muriatic acid to 12 parts water can work. Pre-soak the wall with clean water, apply the solution, and rinse thoroughly. Caution: Acid can damage some brick finishes—check with the manufacturer first.
  • Sealing can help but only after the efflorescence stabilizes. Premature sealing risks cryptoflorescence, where salts crystallize just below the surface, causing spalling or brick disintegration as expanding crystals exceed the brick’s tensile strength.

Why Location Matters

Efflorescence is more common on cooler, shadier North- and East-facing walls, where slower evaporation keeps the point of salt deposition at the surface. South- and West-facing walls, warmed by sun exposure, often push evaporation deeper into the masonry, reducing visible deposits.

Don’t Just Seal It—Solve It

Sealing a wall with active efflorescence is like putting a bandage on a broken bone. The salts, moisture, and pathways are already present, so sealing may trap salts inside, leading to cryptoflorescence. Instead, minimize efflorescence through proper construction and wait for the condition to stabilize before sealing.

The Bottom Line

Efflorescence is controllable with the right materials, smart design, and quality construction. By breaking the chain of conditions—salts, moisture, or migration pathways—you can keep masonry looking pristine and structurally sound. For inspectors, builders, and homeowners, understanding efflorescence is key to spotting it early, addressing it correctly, and preventing costly damage.

Source: Adapted from Masonry Institute (http://www.masonryinstitute.org/pdf/612.pdf)

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