Every April we get the same call. A homeowner notices chunks of brick face on the ground under their front wall and thinks something happened overnight. Nothing happened overnight. What happened was winter, and spring is when you see the bill.
We have been doing this work across the North Shore and northwest suburbs long enough that we can predict the timing almost to the week. The calls start in late March. They peak in April. By May, the homeowners who waited are looking at bigger repairs than the homeowners who called in March. The mechanism does not change. The math does not change.
Here is what is actually going on.
What Winter Does to Brick Before You Can See It
Start with fall. October rain saturates exterior masonry walls over a period of weeks. Brick is porous - all brick, every brick, new and a hundred years old. Water enters through whatever gaps exist: failed mortar joints, small surface cracks, the brick face itself on older material. By the first hard freeze in November or December, the brick has water distributed through its pore network.
Then the temperature drops below 32 degrees. Water expands roughly 9% by volume when it becomes ice. Inside the confined pore space of a brick, that expansion generates hydraulic pressure that can exceed 2,000 PSI. The tensile strength of most fired brick sits between 200 and 500 PSI. The ice is stronger than the brick. Micro-cracks form. Fractures too small to see. But real.
Here is the part that surprises people: through all of this, the brick looks fine. Nothing visible on the surface. The reason is that the frozen water inside is actually holding the weakened surface layer in place, pressing outward in all directions including inward. The brick is damaged but contained.
Then it thaws.
The Chicagoland area runs 80 to 100 freeze-thaw cycles in a typical winter. Not one. Eighty. Each one deepens the micro-cracks, widens the fractures, adds to the cumulative damage. By March, a saturated brick that went into winter with questionable mortar joints has been through months of this.
When spring temperatures finally stabilize above freezing, the ice melts. The compressive force disappears. And the weakened surface layer, which had nothing holding it up from the inside, separates. Thin flakes land on the ground. In worse cases, entire face sections break away. The damage happened in November. You found it in April.
For a full walkthrough of everything else winter left on your property, the Spring Masonry Inspection Checklist covers every element from the chimney crown down.
Why the North Wall Looks Worse Than the South
We hear this question constantly. Same house. Same brick. Same mortar. The north wall is spalling, the south wall is not. Here is the explanation.
Sun exposure is the first factor. South-facing walls get direct sunlight most of the day. Higher surface temperature, faster drying after rain, fewer actual freeze events per winter - often 20 to 30 fewer than the north face of the same house. North-facing walls stay wet longer, freeze more often, and dry more slowly. Three factors working against them, every winter.
East-facing walls are a close second in vulnerability, particularly in communities along the North Shore. Lake-effect moisture from Lake Michigan, morning sun only, and prevailing winter winds all concentrate on that orientation.
The second factor is mortar joint condition. The joint is the primary water entry point. Brick sitting behind intact, properly maintained mortar joints absorbs less water than brick with recessed or crumbling joints. When mortar is gone, water contacts the side faces of the brick directly - the cut or sawn sides, not the fired face, which are the most porous surfaces on the unit. Water absorption is dramatically higher there, and the freeze-thaw damage is proportionally worse.
We see this most clearly on the 1920s bungalows along Dempster and on the post-war ranches in Park Ridge. One elevation repointed correctly 15 years ago, holding up fine. The opposite elevation never touched, joints now recessed a quarter inch or more, spalling visible from the street. Same brick. Different mortar maintenance.
The third factor is previous repair work. A wall that was repointed with Portland cement mortar harder than the original brick is going to spall at the mortar-brick interface regardless of orientation or weather. That spalling looks like freeze-thaw damage from a distance. Up close it concentrates at the joint edges in a specific pattern. See What Causes Brick Spalling and How to Prevent It for how to read the difference.
On homes in Evanston, Highland Park, or Glenview with original 1890s through 1930s brick, we find real variation in spalling rates even within a single wall. Brick from different parts of the same kiln batch can have meaningfully different absorption rates. The fired outer surface of old brick is not uniform.
See When to Schedule Tuckpointing in Illinois for the right window to address joint conditions before next winter.
Reading What You Find in Spring
When you walk the exterior in April, you are reading two different things: what happened this winter, and what has been happening for longer than that.
Fresh spalling from the current season has clean, sharp fracture edges. The exposed brick interior is lighter colored - the fired outer surface was darker; the interior clay is lighter. Pieces of the face may still be on window sills or the ground below. The exposed surface has not yet absorbed dirt or weathered.
Prior-season spalling that was not repaired looks different. The exposed interior has already darkened. Fracture edges are rounded where additional freeze-thaw action has continued working at the exposed zone. The damaged area is larger than it was last spring.
Both need attention. Prior-season spalling is more urgent because the unprotected brick interior is absorbing water at two to four times the rate of the original surface. Every winter you leave it, the damage zone grows.
Pattern recognition helps identify the cause. Spalling concentrated at mortar joint edges points to mortar-hardness mismatch from a prior repointing job. Spalling on the upper third of a north or east-facing wall typically connects to water entry at the roof or window head above. Spalling at the base of a wall suggests ground splash, failed drainage, or water pooling against the foundation. Spalling across an entire elevation with no pattern means widespread joint failure allowing full-face saturation.
For chimney-specific spalling, the cause is usually a failed crown - a separate pattern worth reading separately. See Spring Chimney Crown Damage: The Winter Aftermath Homeowners Miss.
If you are seeing white deposits alongside the spalling, those two conditions share the same root cause. See Efflorescence and White Staining in Spring for the connection.
What It Costs to Wait
A spalled brick face is not cosmetic. The fired outer surface is the protective layer. Once it is gone, the exposed interior absorbs water at two to four times the normal rate. The next winter hits harder. Adjacent bricks pick up elevated moisture. The damage zone grows.
A 10-brick spalled section in spring 2026 left untreated typically becomes 20 to 30 bricks by spring 2027. A 10-brick replacement runs $400 to $800. A 30-brick section with mortar work runs $1,200 to $2,500. When the damage has spread to 60 or 80 bricks and the affected area requires a section rebuild, you are looking at $4,000 to $8,000.
Spring is the right time to act. Brick can be replaced during warm weather with adequate time to cure before the next freeze season. Mortar can be matched and applied under conditions that produce a good result.
Delta Masonry & Tuckpointing serves Libertyville, Northbrook, and surrounding communities across Lake County and the North Shore. If you are seeing spalling this spring, call (847) 713-1648 or request a free inspection online. We would rather look at a 10-brick problem than come back for the 80-brick version next year.