Three separate agents attack your masonry every winter in Chicagoland, and most homeowners are only aware of one. Understanding all three - snow and meltwater, ice expanding inside joints, and de-icing salt - changes how you look at your brick and concrete in December and gives you specific, actionable ways to limit the damage before it shows up as a spring repair bill.
Winter brick damage is not random or inevitable. It follows predictable pathways, concentrates in predictable locations, and is significantly influenced by decisions you make about maintenance and de-icing products throughout the season.
The First Winter Masonry Threat: Snow, Meltwater, and Saturation
Snow itself rarely damages masonry directly. The real threat is what happens when it melts.
Fresh snow is relatively benign. It sits on horizontal masonry surfaces - chimney crowns, window sills, coping, and step treads - and insulates more than it damages. The problem begins at the melt stage. When temperatures rise above 32 degrees Fahrenheit, or when solar radiation warms a south-facing surface even on cold days, snow converts to liquid water.
That meltwater looks for the fastest path downward. On a properly maintained masonry surface, it flows off and away. On a surface with open mortar joints, it flows in. And unlike rain, which delivers moisture in discrete events between which masonry can dry, snow creates a multi-day saturation event. A large snowfall followed by gradual melt over three to five days means several days of continuous moisture input into any open joint.
Mortar joints are the weak link in any brick wall. When they erode and recess below the brick face, they become channels that collect water and direct it inward rather than shedding it outward. A joint recessed half an inch below the brick face is a small valley that holds water against the masonry instead of draining it away. BIA Technical Note 7B establishes that joints must be tooled to shed water outward - a recessed or improperly profiled joint is an open invitation for water infiltration under every melt event.
Horizontal surfaces take the worst of the snow and melt load. Chimney crowns, brick sill courses, parapet caps, and step treads bear the full weight of accumulated snow and then hold water as it melts. A chimney crown with hairline cracks from thermal cycling is functioning as a funnel - every meltwater event sends water directly into the chimney structure. Chimney crown failure is among the most common winter masonry findings and the most preventable with timely repair.
On Glencoe’s ravine-side properties, the meltwater risk has a geographic amplifier. Glencoe’s ravines create catchment areas where meltwater concentrates and drains toward foundation masonry. The ravine micro-climate limits air circulation, which means ravine-facing walls stay wet significantly longer than street-facing walls after each melt cycle. Foundation and lower-wall mortar erosion on Glencoe ravine-adjacent homes shows measurably greater deterioration on the ravine-facing elevation than on the street side of the same house. Those shaded facades hold snow pack for days after the sunny side is clear, concentrating the meltwater cycle on an already moisture-stressed surface.
The Second Winter Brick Damage Threat: Ice Expansion in Joints
This is the mechanism responsible for most of the visible winter brick damage you will see in a Chicagoland spring, and it is worth understanding in some detail.
Water expands approximately 9 percent by volume when it freezes. That number sounds modest until you think about what it means inside a mortar joint.
A mortar joint is not a simple channel. Mortar is porous. Water absorbed into the joint occupies tiny spaces within the material - capillary pores, micro-cracks from weathering, and the interface between the mortar and the brick face. When temperature drops to 32 degrees Fahrenheit, every molecule of that absorbed water expands. The expansion is constrained by the surrounding material. The pressure generated by that constrained expansion is substantial - estimates range from hundreds to thousands of pounds per square inch depending on the saturation level and the confinement geometry.
Mortar in a deteriorated joint cannot withstand that pressure repeatedly. The first freeze cycle opens cracks that were not there before. Each subsequent cycle finds a slightly larger, slightly more accessible space for water to penetrate before the next freeze. The damage accumulates through the winter. By spring, joints that showed minor recessing in October show significant cracking, spalling, and material loss.
This process explains why Libertyville’s winter damage profile is more aggressive than some might expect given the inland location. Libertyville masonry does not experience one extended freeze followed by one spring thaw. It experiences dozens of individual freeze events, each one exerting mechanical pressure on whatever water has been absorbed. The cumulative mechanical work done on mortar joints through a Libertyville winter is far greater than in a climate with fewer but deeper freezes. GLISA at the University of Michigan identifies the Great Lakes region as one of the highest freeze-thaw frequency zones in the country, which is the underlying reason Libertyville’s masonry ages as it does.
The same freeze-thaw mechanism explains the geographic pattern of damage on individual houses. North-facing walls receive less solar radiation, meaning the ice in their joints stays frozen longer and the thaw-refreeze cycle can complete multiple times in a single day on a winter day that swings above and below 32 degrees. South-facing walls, warmed by even winter sun, dry faster between cycles. This is why north-facing masonry on any home typically shows more deterioration at the same age than the south elevation.
For brick on Northbrook homes built during the 1960s through 1980s building boom, the builder-grade mortar that was adequate when installed has now been subjected to thousands of individual freeze-thaw cycles. ASTM C270 specifies Type N mortar at a minimum compressive strength of 750 PSI for above-grade residential work - the mortars placed in those 1960s to 1980s Northbrook homes were mixed to the standards of the era and have now been mechanically stressed through decades of cycling. The joints are no longer providing the water-exclusion function the wall depends on, making tuckpointing on these homes genuinely necessary structural repair rather than optional maintenance.
Ice on Horizontal Surfaces: Crowns, Sills, and Steps
Freeze-thaw damage concentrates most severely on horizontal masonry surfaces because water does not drain away - it pools.
Chimney crowns are the most vulnerable horizontal masonry element on any home. The crown is the concrete or mortar cap that covers the top of the chimney, leaving only the flue opening. A properly designed crown has an overhang that directs water away from the chimney face. A properly constructed crown is thick enough to resist cracking from thermal cycling and surface ice formation.
The reality on most Chicagoland homes built before the 1990s is thinner crowns poured without adequate reinforcement. After 30 to 50 years of freeze-thaw cycling, these crowns develop hairline cracks that widen each winter. Deerfield homes from the 1960s through 1980s are a representative example: concrete chimney crowns on those homes were often poured thin without reinforcement. After 40-plus years of freeze-thaw, these crowns crack, and each winter’s ice formation in those cracks widens them further. Deerfield’s documented top-problem profile includes steel lintel rust and crown failure working together - water entering through a cracked crown accelerates lintel corrosion below. A crown with an open crack is no longer protecting the chimney; it is directing water into the chimney’s brick core with every melt cycle.
Window sills and door sills are horizontal surfaces exposed to the same pooling and ice formation. Brick sills that are poorly pitched or have deteriorated joint caulk at the junction with the frame hold water and ice through winter. Sills cracking from this process are common on the 1960s to 1980s colonials and split-levels that make up much of Northbrook’s and Libertyville’s housing stock.
Brick steps and stoops have the same vulnerability. A step tread that is level rather than pitched slightly outward holds water and forms ice that sits against the riser masonry. Over multiple winters, this concentrated freeze-thaw action deteriorates step mortar and brick faces at the riser junction faster than any other part of the step.
The Third Threat: De-Icing Salt and Chemical Attack on Masonry
De-icing salt is the most misunderstood winter masonry threat because the damage pathway is less visible than ice formation.
Rock salt - sodium chloride - works by lowering the freezing point of water. When applied to ice on driveways and walkways, it melts the ice by forming a brine solution that stays liquid at temperatures where pure water would freeze. That brine does not stay where it is applied. It migrates with every subsequent melt event. Splash from passing vehicles carries it. Foot traffic distributes it. Runoff channels it to adjacent surfaces, including the lower courses of brick walls and foundation masonry at the perimeter of driveways and walks.
ACI 318 specifies air-entrained concrete for freeze-thaw climates in part because chloride penetration from de-icing salts is a primary cause of concrete deterioration - the same chloride-driven deterioration mechanism operates on mortar joints and brick pores in masonry.
Libertyville’s documented climate factors include de-icing salt damage to concrete and lower masonry courses as a primary concern. The Libertyville housing stock - predominantly 1950s to 1980s construction with driveways, entry walks, and steps adjacent to brick masonry - faces this problem every winter. The lower two or three courses of brick on the garage facade, the brick cheek walls flanking entry steps, and the concrete foundation at grade level all receive salt contact throughout the season.
Two damage mechanisms are at work. First, salt crystals that form inside masonry as the brine dries exert expansive pressure similar to ice formation. Salt crystallization in brick pores and mortar capillaries physically breaks down the material from the inside. This process is called subflorescence when it occurs inside the material and creates the surface scaling and flaking you see on salt-damaged lower courses in spring. Second, chloride ions in salt solutions aggressively corrode any ferrous metal - steel lintels, brick ties, reinforcing bar - embedded in or adjacent to the masonry. Salt-accelerated lintel corrosion is one of the primary causes of the displaced brick we see above window and door openings on Northbrook and Libertyville homes where road and entry salt has been applied consistently for decades.
Northbrook homeowners should note that de-icer impact on concrete and lower masonry is documented as a primary climate factor for their community. The hard machine-pressed brick used in Northbrook’s 1960s to 1980s construction is more resistant to salt damage than older soft brick, but it is not immune. Mortar joints on lower courses are the entry point, and once salt has penetrated the joint, it works on both the mortar and the brick interior through every subsequent melt cycle. Spring concrete damage assessments consistently show the worst scaling on surfaces closest to areas of heavy salt application.
Concrete flatwork is even more vulnerable than brick to salt damage. Concrete surfaces absorb salt solution readily, the chloride ions attack the aggregate-cement interface, and the freeze-thaw pressure from salt-accelerated ice formation degrades the surface at a rate significantly faster than unsalted concrete.
How Glencoe’s Ravine Side and Shaded Facades Concentrate Winter Damage
Glencoe presents a combination of winter threats that deserves specific attention because the topography amplifies what would otherwise be standard Chicagoland winter masonry stress.
Glencoe’s ravines are natural drainage channels. In summer, they are pleasant green spaces. In winter, they are moisture traps that keep cold air pooled, limit air circulation, and direct meltwater toward any masonry in the drainage path. Homes along the ravine edges have their ravine-facing walls exposed to conditions that are measurably more demanding than the street-facing side of the same house.
A Glencoe home with a ravine-facing south wall might seem like it would benefit from solar exposure. But the geometry often places these walls in the shadow of the ravine cut itself, particularly in winter when the sun angle is low. The result is a wall that is both in the cold-air drainage zone of the ravine and in shadow during the brief winter warm periods that would otherwise dry it out.
The shaded-facade problem extends to homes with heavy tree canopy that shades north and northeast walls. Dense tree cover in Glencoe’s residential streets limits winter drying on any facade it shadows. Mature trees that overhang the north side of a house can extend the period of surface ice and snow pack by days after adjacent open areas have cleared. The masonry underneath stays wet longer. The freeze-thaw cycles do more work.
This combination - ravine moisture, reduced air circulation, shaded facades holding snow and ice - makes Glencoe a community where winter masonry damage concentrates rather than distributes evenly. The ravine-side and north-facing walls on Glencoe properties typically need more frequent inspection and earlier intervention than the street-facing and south-facing elevations.
What You Can Do This Winter to Limit Masonry Damage
Understanding the three threat categories leads directly to practical steps.
On meltwater: Keep horizontal masonry surfaces clear of snow when practical, particularly chimney caps, sills, and step treads. Inspect chimney caps and crowns now - a crack in the crown that you can seal with elastomeric crown coating before winter fully sets in is a $200 to $600 investment that prevents the $3,000 to $6,000 partial rebuild that results from a winter of unobstructed water entry. If your crown is already cracked through, emergency masonry repair options exist even in cold weather for the chimney’s most critical elements.
On ice in joints: You cannot prevent freeze-thaw cycling. You can reduce the moisture available for it by ensuring mortar joints are not open going into winter. For this season, the practical action is documentation - know which joints are eroded and where the open sections are - so that spring tuckpointing is targeted and efficient. Scheduling your masonry repair before winter is easier in September than in December, but understanding the scope in December still puts you ahead for spring scheduling.
On salt: Consider alternatives to rock salt on surfaces adjacent to masonry. Sand provides traction without chemical attack. Calcium magnesium acetate (CMA), while more expensive, causes significantly less damage to concrete and masonry than sodium chloride. Where chloride de-icers are used, concentrate application away from brick foundations and lower wall courses when possible, and plan for a spring flush of hardscaping surfaces to remove salt accumulation before warm weather drives it deeper into the material.
Avoid applying de-icing products directly on brick steps or stoops unless they are newer construction with dense, hard brick. Sand is a better choice for traction on brick step surfaces.
Why Spring Spalling Looks Sudden But Is Not
The visual pattern that surprises most homeowners is this: brick looks reasonably intact through most of winter, then in March and April the faces start coming off. The damage appears sudden.
It is not sudden. It is cumulative. What you see in spring is the result of the entire winter’s freeze-thaw and salt activity. Each cycle deposited a small amount of additional stress. The brick face that was nearly at its fracture point in October finally fractures in February during the last hard freeze before spring. The spalled face does not detach until the ice that holds it in place melts in March.
Why brick spalling appears in spring covers this mechanism in detail. The practical implication is that spring spalling is not a reason to call a contractor in April - it is a reason to call in November or December. For homes where spalling has already appeared on previous spring assessments, what causes brick spalling and how to prevent it explains both the mortar compatibility factors and the freeze-thaw factors that produce this damage mode.
For a deeper understanding of exactly what the freeze-thaw mechanism does to Chicagoland brick year after year, see our pillar post on Illinois freeze-thaw damage to brick.
Getting Ready for the Assessment Season
December is not too late to act on winter masonry concerns. The freeze-thaw damage cycle runs from roughly December through March in Chicagoland. Acting before January limits exposure to the hardest freeze periods of the season.
For Libertyville and northwest suburban homeowners: focus on chimney crown condition, lower course mortar at grade level, and any concrete surfaces that received heavy salt application last season. These are the three highest-risk categories given Libertyville’s documented winter climate factors.
For Glencoe and North Shore homeowners: add a specific check of ravine-facing and north-facing walls for moisture damage, and look at chimney joints on any chimney exposed to lakefront or ravine wind exposure.
For Northbrook homeowners: check lower masonry courses and concrete flatwork adjacent to driveways and entry walks where salt concentration is highest. Northbrook’s 1960s to 1980s builder-grade mortar is at or past expected service life on many properties, and salt exposure accelerates failure in already-deteriorated joints.
For the full picture on winter damage patterns, see what winter does to Chicago masonry and spring concrete damage from de-icer salt.
Delta - Masonry and Tuckpointing has served Lake County and the North Shore since 1987. We perform free inspections year-round. For Libertyville, Glencoe, Northbrook, Wilmette, and communities across the North Shore and northwest suburbs, call (847) 713-1648 or contact us online to schedule an assessment before the hardest part of winter arrives.
De-icing salt on your driveway does not stay on your driveway. Splash and drift carries it to lower brick courses and concrete flatwork for the entire season.