Spalling brick looks like the outer face of the brick has flaked, peeled or popped off, leaving a rough, pitted, often lighter surface underneath. It can show up as small shallow scars or as faces missing from a whole run of bricks. Water getting into the brick, then freezing or leaving salts behind, is the usual cause. Spalling is different from white powder on the surface or from crumbling mortar between the bricks.
If you are standing in front of your wall asking what you are looking at, start with this: spalling is damage to the brick itself, not to the mortar around it. The hard outer skin of the brick lets go, and what is left underneath is softer, rougher and more exposed to water.
What does spalling brick look like up close?
Look for these signs, from early to advanced:
- Flaking or peeling faces. The surface looks like it is shedding thin layers, the way old paint peels.
- Pitted or scooped-out spots. A brick that looks chewed, with a rough recess where the smooth face used to be.
- Missing faces. The face is gone from one brick or a patch of them, and the exposed material is a different color or texture than the bricks around it.
- Debris below. Small chips, grit or red dust on the ground, window sill or porch floor under the wall.
- Damage that repeats. Several bricks in the same area, often low on a wall near the ground, under a roofline, around a downspout or leaky gutter, or near a chimney or parapet.
The brick next to a spalled one may look perfectly fine. Spalling is often patchy because moisture and salts reach some bricks more than others.
Why does brick spall?
The National Park Service explains that salt crystallizing inside a brick creates pressure that can make the outer surface spall or delaminate, and that freeze-thaw of saturated brick is another cause (NPS and BIA guidance). The same NPS brief shows how it can start with mortar: when the mortar is harder and less permeable than soft brick, moisture and salts move out through the brick instead, and trapped moisture eventually pops the surface off (NPS Preservation Brief 2).
In Chicago, brick goes through a lot of freezing and thawing every winter, which is why this shows up so often on older two-flats and greystones. How that cycle damages brick is covered in freeze-thaw damage.
On older Chicago buildings, spalled bricks often sit right where water collects: below a failed gutter, at the base of a wall where snow piles up, or on a wall that was repointed with a mortar harder than the brick. The pattern is usually water first, damage second.
What looks like spalling but isn't?
- White powder or crust on the face. That is efflorescence, salts left behind as water dries out. The surface kind is usually harmless, and it points to a moisture problem to track down (BIA guidance).
- Crumbling or missing mortar. Sandy, recessed or cracked joints are a mortar problem, not a brick problem. See signs your brick needs tuckpointing.
- Dirt, soot or stains. Surface color change without loss of material is cosmetic until the brick starts to flake.
What should you do if you see it?
Photograph it, note where it is, and watch whether it grows. A flaked face on a low, protected wall is something to monitor. Loose faces or whole bricks high on a wall, parapet or chimney, above a sidewalk, gangway or entry, are a different matter, because the City can cite exterior masonry that is not kept in good repair or properly anchored (City of Chicago code). Read are spalling bricks dangerous to judge urgency, and can you fix spalling brick without replacing it for the repair options.
Not sure what you are seeing? Our masonry crew can look at it, and the full brick and masonry repair guide shows how the pieces fit together.
Common questions
Spalling means the outer face of a brick has flaked, peeled or popped off. It is damage to the brick itself, usually driven by moisture, freezing and thawing, or salts crystallizing inside the brick, and not simply worn mortar.
No. White powder is efflorescence, salt left on the surface as water dries. The surface kind is usually harmless, but it signals moisture moving through the wall. Spalling is the face of the brick breaking away.
Yes. Once the hard outer face is gone, the softer brick underneath takes in water more easily, so damage often spreads if the moisture source is not fixed. Have a mason look at it before the next winter.
Sources
- National Park Service: Preservation Brief 2: Repointing Mortar Joints in Historic Masonry Buildings (PDF)
- Brick Industry Association: Technical Note 23A: Efflorescence, Causes and Mechanisms (PDF)
- City of Chicago: Code Modernization Ordinance, including Title 14X Minimum Requirements for Existing Buildings (PDF)
Facts last checked: October 7, 2026.
This article explains general rules and common situations in Chicago. It is not legal advice, and City rules change. For a specific property, check with the Chicago Department of Buildings or a licensed professional.