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 since 1987. 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 ones who called in March. The mechanism does not change. The math does not change.
Here is what is actually happening.
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 approximately 9% by volume when it becomes ice. Inside the confined pore space of a brick, that expansion generates hydraulic pressure that can exceed the tensile strength of the fired clay. The ASTM C67 standard test methods for freeze-thaw durability measure exactly this failure mechanism - resistance to repeated saturation and freezing cycles. On weathered pre-1940 brick that has already absorbed decades of moisture, the threshold is lower than on new production units. 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. 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.
GLISA Great Lakes climate analysis documents the Chicago region as one of the highest freeze-thaw frequency zones in the continental U.S., with many dozens of cycles in a typical winter. 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. 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 for Illinois covers every element from the chimney crown down.
Why Brick Spalling Appears Worse on North and East Walls
We hear this question constantly. Same house. Same brick. Same mortar. The north wall is spalling, the south wall looks fine. 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 along the North Shore. Lake-effect moisture from Lake Michigan, morning sun only, and prevailing winter winds concentrate on that orientation. In Evanston, where the median home dates to 1939 and direct lake exposure spans the entire eastern border, east-facing facades show accelerated mortar erosion and spalling compared to identical construction a mile inland.
The second factor is mortar joint condition. The joint is the primary water entry point. Brick sitting behind intact, properly maintained mortar joints absorbs far 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 in Northbrook, where homes from the 1960s through 1980s building boom used builder-grade mortar that is now reaching the end of its service life. One elevation repointed correctly 15 years ago holds up fine. The opposite elevation never touched, joints 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 repointed with Portland cement mortar harder than the original brick spalls 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.
In Highland Park, where homes from the 1920s through 1940s were frequently repointed with Portland cement mortar in the 1960s through 1980s, this mortar incompatibility pattern is the most common spalling source on pre-war construction. The mortar looks intact. The brick face is separating at the joint lines. The repair caused the damage.
On homes in Glenview with original 1950s through 1960s hard machine-pressed brick, freeze-thaw spalling is less frequent because hard brick tolerates more moisture cycling. But chimney flashing failure at the roofline creates concentrated water entry points above the wall, and the resulting spalling follows a vertical strip down from the chimney base.
See when to schedule tuckpointing in spring and summer in Illinois for the right window to address joint conditions before next winter.
Reading What You Find in a Spring Walk-Around
When you walk the exterior in April, you are reading two different things: what happened this winter, and what has been accumulating for longer than that.
Fresh spalling from the current season has clean, sharp fracture edges. The exposed brick interior is lighter - the fired outer surface was darker; the interior clay is lighter. Pieces of the face may still be on window sills or on 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 unprotected brick interior absorbs water at two to four times the rate of the original surface. Every winter left, the damage zone grows.
Pattern recognition identifies the cause. Spalling concentrated at mortar joint edges points to mortar-hardness mismatch from a prior repointing job - the NPS Preservation Brief 2 principle that mortar must be softer than the brick it joins was violated at some point. 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. 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.
In Libertyville, where the mid-century housing stock has chimneys now 40 to 60 years old, crown cracking is often the first spring discovery. The crown failure drives water down the chimney face, saturating the upper courses, and the spalling appears a foot or two below the crown line by April.
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 25 to 30 bricks by spring 2027. A 10-brick replacement runs approximately $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, the cost moves to $4,000 to $8,000. These figures are ranges; a written estimate requires an on-site assessment.
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 lasting result. See the complete guide to brick spalling and prevention for the full repair context, or brick replacement versus tuckpointing if you are deciding which scope applies.
Brick Type and How It Changes the Spring Damage Picture
Not all spring spalling reads the same, because not all brick is the same material. Two houses on the same street can show completely different spalling patterns from the same winter.
Pre-1920 soft Chicago common brick - the salmon-to-buff material in Evanston’s greystones, the bungalow belt from Skokie through Lincolnwood, and the oldest homes in Highland Park - is the most vulnerable to freeze-thaw spalling because it was fired at lower temperatures, is more porous, and was designed to work with lime mortar that allows moisture to migrate through. When those joints have been replaced with Portland cement mortar at some point in the past, water that enters the brick cannot exit through the harder mortar. It concentrates. It freezes. The face separates.
Hard machine-pressed brick - the dominant material in Northbrook’s 1960s through 1980s split-levels and ranches, and in Glenview’s post-war neighborhoods - is less porous and more resistant to freeze-thaw cycling. Spring spalling on these homes usually traces to a specific entry point: a failed chimney crown, a cracked window head lintel, or a section of wall where a horizontal surface (a window sill, a ledge) is directing water into the vertical joint rather than away from it. The brick is not the problem. The detail failure is the problem.
In Libertyville, where the housing stock is predominantly mid-century and newer, the spring calls are more often about chimney sections than about wall-face spalling. Chimneys are the most exposed masonry on any structure - no overhang protection, fully exposed on four sides, and subjected to more freeze events per winter than a wall that is partially shielded by the roof. A Libertyville chimney from the early 1970s that has never been tuckpointed is now 50 years old. The mortar at the top courses is gone in places. Spring reveals this as staining below the crown and, in worse cases, displaced bricks at the upper courses.
For which repairs apply at which damage stage, the complete guide to brick spalling and how to prevent it covers every brick type and repair scope.
Scheduling an Assessment
Delta - Masonry and Tuckpointing serves Evanston, Highland Park, Glenview, 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.