You are cleaning up the yard after a long Wisconsin winter when you notice a pile of reddish chips at the base of the chimney. Look closer, and the faces of several bricks have flaked away, leaving rough, crumbling patches where smooth brick used to be.
The natural fear is that the wall is failing and that you are staring down a major structural repair.
Here is the reassuring part. Spalling brick is a common freeze-thaw problem, it makes sense once you understand what caused it, and it is often repairable when you catch it early. The important warning is this: the wrong kind of protection, especially a non-breathable sealer, can make spalling much worse. So the fix has to be done in the right order.
The Short Answer: What to Do When Brick Is Spalling
Brick spalls when water soaks into the porous brick, freezes, and expands, popping the face off, and it worsens with every freeze-thaw cycle. To fix it, stop the water source, repair or replace the damaged brick, and repoint with a compatible soft mortar. Never seal spalling brick with a non-breathable coating.
Your First Steps
- Stop the water. Spalling is a moisture problem, so fix drainage, gutters, downspouts, and any leak feeding the wall.
- Assess how bad it is. A few surface flakes is very different from deep, widespread damage or a wall losing structural brick.
- Repair correctly. Replace badly spalled brick and repoint with a mortar softer than the brick, never hard Portland cement on soft old brick.
- Do not seal it with a non-breathable coating. Trapping moisture behind the face accelerates the damage.
What Brick Spalling Is and Why It Happens After Freeze-Thaw
Spalling is not random. It follows water, cold, and a few common mistakes. Once you see the mechanism, the right fix becomes obvious.
The Freeze-Thaw Mechanism
Brick is porous by nature. It soaks up water like a sponge, especially where mortar has failed or where rain and snowmelt sheet down a wall.
When that saturated brick freezes, the trapped water expands by roughly nine percent as it turns to ice. That expansion pushes outward from inside the brick with enough force to break the hardened outer face right off.
Wisconsin does not freeze and thaw just once. We cycle through it over and over from late fall into spring. Each cycle pops off a little more of the face and exposes fresh, softer brick to the next round of water, which is exactly why spalling gets worse every winter it is left alone.
What Makes It Worse
Freeze-thaw is the engine, but several things pour fuel on it. Most of the spalling our crews get called to look at has one or more of these behind it.
- Poor drainage. Clogged gutters, bad downspouts, missing flashing, or soil graded toward the wall keep the brick soaked.
- Failed mortar joints. Cracked or missing mortar lets water run straight into the wall.
- Hard mortar on soft brick. When old, soft brick was repointed with hard Portland cement, the brick becomes the weakest point and spalls instead of the mortar.
- De-icing salts. Salt splashed onto steps, foundations, and lower walls drives extra damage, which we see constantly on Wisconsin entries and garage aprons.
- Corroding embedded metal. Rusting wall ties or lintels expand and crack the surrounding brick.
- Over-pressure washing. Blasting brick with high pressure erodes the face and forces water deep into it.
That last one matters, because plenty of well-meaning homeowners accelerate spalling while trying to clean it up.
The Efflorescence and Subflorescence Connection
Salt plays a quieter role too. Water moving through brick carries dissolved salts, and when the water evaporates, the salt is left behind.
When those salts crystallize on the surface as a white, chalky bloom, that is efflorescence. When they crystallize inside the brick, just under the face, that is subflorescence, and it is the more destructive of the two.
Subflorescence pushes outward from within the same way ice does, feeding the spalling from the inside. If you are also seeing white residue on your brick, it is a signal that water and salt are moving through the wall, and one more reason the water has to be stopped first. (We cover this in our separate article on efflorescence on masonry.)
The Biggest Mistake: Sealing Brick with a Non-Breathable Coating
If you take one thing from this article, take this. Do not seal spalling brick with a non-breathable, film-forming sealer or coating.
It feels logical to lock water out with a heavy sealer. On masonry it backfires. Brick needs to dry outward, and an impermeable film traps moisture behind the brick face, where it keeps freezing, thawing, and salting.
The result is faster spalling, not slower, and sometimes the face lets go in larger sheets because the trapped water has nowhere to escape. Any protection you put on brick has to let vapor pass. That single property, breathability, is the difference between protecting brick and destroying it.
Is Spalling Serious? When to Act
Early on, spalling looks cosmetic. Over time it is anything but.
Every popped face exposes softer inner brick to water, so the damage accelerates and spreads. Left long enough, spalling eats into the structural body of the brick and weakens walls, and around chimneys and load points it becomes a genuine safety concern.
The practical takeaway is simple. A handful of spalled bricks repaired this year is a small job. A wall left to crumble for five more winters is a big one. Catching it early is by far the cheapest path.
How to Fix and Prevent Spalling Brick, Step by Step
There is a right order to this, and skipping ahead is what gets homeowners in trouble. Water first, repair second, protection last.
Step 1: Stop the Water First
This step is non-negotiable, and it comes before any repair or coating. Spalling is a water problem, so the water has to be addressed first or it simply happens again.
Clean and repair gutters and downspouts so runoff is carried well away from the wall. Check and fix flashing, and make sure the ground slopes away from the foundation rather than toward it.
Where de-icing salt is the culprit, cut back salt use near brick steps and foundations, switch to a gentler ice melt, and rinse the area in spring. Getting the wall to stay dry is most of the battle.
Step 2: Assess the Severity
Next, judge how far the damage has gone. This decides whether you repoint, replace brick, or both.
Light surface flaking on otherwise sound brick, with good mortar, may only need the water fixed and some monitoring. Deeper spalling, crumbling brick, and failed mortar joints call for hands-on repair. Widespread structural loss, especially on a chimney or load-bearing wall, needs a mason’s eyes, not a guess.
Step 3: Replace Severely Spalled Brick and Repoint with Compatible Soft Mortar
Severely spalled or crumbling bricks should be cut out and replaced with matching units. The failed mortar around them gets raked out and repointed, a process also called tuckpointing.
The critical detail here is mortar compatibility. The mortar must be softer than the brick, so it acts as the sacrificial layer and wears before the brick does.
On older, soft Wisconsin brick, that usually means a softer, lime-rich mix rather than a hard, modern Portland cement mortar. Repointing soft brick with hard mortar is one of the most common ways we see spalling made worse, because the hard joint forces the stress back into the brick face.
Step 4: Let the Masonry Fully Dry
Do not rush to protect a wall that is still holding moisture. Fresh repointing and previously saturated brick both need time to cure and dry out.
Sealing or coating a damp wall traps the very moisture you are trying to manage. Depending on the season and the wall, that drying window can take weeks, and in Wisconsin it is worth timing the work for a drier stretch.
Step 5: Protect with a Breathable System Only, If Appropriate
Once the water is stopped, the brick is repaired, and the wall is dry, you can consider protection. The rule does not change: it must be breathable.
Breathable options include penetrating water repellents, such as siloxane or silane, which soak in and shed liquid water while letting vapor pass, along with vapor-permeable coatings and mineral silicate systems. What they share is permeability.
This is where a modern vapor-permeable coating fits honestly, because it blocks wind-driven rain while still letting the wall dry outward. It is also where an honest crew will tell you whether your wall needs repair only, a penetrating repellent, or a breathable coating, rather than selling everyone the same answer.
When to Do This Yourself and When to Call a Pro
Some of this is DIY-friendly. Cleaning gutters, improving drainage, cutting back salt use, and gently rinsing brick are all reasonable to handle yourself.
Repointing, matching mortar hardness and color, and replacing brick are skilled masonry work. Get them wrong, with hard mortar or a poor match, and you can cause the very spalling you set out to stop. For anything past surface care and drainage, bring in a pro.
Why Breathability Is Everything on Masonry
Breathability is the concept that separates protecting brick from wrecking it. It is worth understanding before you let anyone put a product on your wall.
Liquid Water Out, Vapor Out
Masonry is a system that has to breathe. Brick and mortar constantly take on a little moisture and release it as vapor, and a healthy wall dries about as fast as it gets wet.
The right protective finish blocks liquid water, the rain and snowmelt that saturate brick, while still letting water vapor pass through and escape. Rhino Shield is formulated to be vapor-permeable and breathable for exactly this reason, which is the correct property type for masonry.
The wrong finish blocks both directions and turns the wall into a moisture trap. That difference, breathable versus impermeable, is the whole ballgame on brick.
Why We Assess Each Wall Honestly
Breathability is necessary, but it is not the only question. A coating is not automatically the right call on every brick wall.
Some walls just need the water stopped and the mortar repaired. Some are better served by a penetrating repellent than a coating. Some genuinely benefit from a breathable protective coating once they are sound and dry.
That is why we assess each wall on its own before recommending anything. Repair always comes first, and we would rather tell you a coating is not needed than sell you one that is wrong for your masonry.
How We Handle Spalling Brick in Wisconsin
By the time a homeowner calls us about crumbling brick, they are usually braced for the worst and half-expecting us to quote a coating on the spot. That is not how we work on masonry.
Our inspection starts by finding the water. We look at gutters, downspouts, flashing, grade, and salt exposure, because until we know why the brick is getting wet, nothing else matters.
Then we judge the brick and mortar. We check how deep the spalling goes, whether joints have failed, and whether old brick was repointed with a mortar that is too hard for it.
From there we coordinate the right repair, replacing damaged brick and repointing with a compatible, softer mortar, and we let the wall dry fully before anyone talks about protection.
“People are sometimes surprised when we tell them not to coat their brick yet, or at all,” says Mike Moore, co-owner of Rhino Shield of Wisconsin and a certified coating inspector with more than 25 years in coatings and paint chemistry. “Spalling is a water problem first. If you seal an active, wet, crumbling wall with the wrong product, you trap the moisture and speed up the damage. We fix the water and repair the brick first, every time. A breathable coating only makes sense on masonry that is already sound and dry.”
Only when a wall is sound, dry, and stable do we consider a breathable protective system, and sometimes we advise against a coating altogether.
One pattern we see across Wisconsin masonry: the homeowners who fix the water and repair the brick properly stop losing brick every winter, whether or not a coating ever goes on. When a breathable coating is the right fit, it goes onto sound brick and is backed by our 25-year transferable warranty.
Frequently Asked Questions
What causes brick spalling?
Brick spalling is caused by water and freeze-thaw. Porous brick absorbs moisture, and when that water freezes it expands and pushes the hardened outer face off the brick. Poor drainage, failed mortar, hard Portland cement on soft brick, de-icing salts, and corroding embedded metal all make it worse. In a high-cycle freeze-thaw climate like Wisconsin, the damage repeats and spreads every winter it is ignored.
Can you fix spalling brick without replacing it?
Sometimes. Lightly spalled brick that is still sound may only need the water source fixed and the mortar repaired, with monitoring afterward. Deeper spalling, crumbling faces, and failed joints usually require replacing the worst brick and repointing with compatible mortar. The key is stopping the water first. A wall that stays wet will keep spalling no matter how much surface repair you do.
Should you seal spalling brick?
Not with a non-breathable sealer. Impermeable, film-forming sealers trap moisture behind the brick face and make spalling worse. If you protect brick at all, it must be with a breathable, vapor-permeable product, such as a penetrating siloxane or silane repellent or a breathable coating, and only after the water is stopped, the brick is repaired, and the wall is fully dry. Sealing an active, wet, spalling wall is a mistake.
Is spalling brick a structural problem?
It can become one. Early spalling looks cosmetic, but each popped face exposes softer inner brick to more water, so the damage accelerates. Left for years, it eats into the structural body of the brick and weakens walls, and around chimneys or load-bearing sections it becomes a real safety concern. Caught early, it is usually a manageable repair, which is why acting sooner is far cheaper.
Can you paint or coat over spalling brick?
You should never paint or coat over actively spalling brick as a fix. The face is unstable and the wall is holding water, so a coating will not bond well and can trap moisture. The correct order is to stop the water, replace and repoint the damaged brick, let it dry, and only then apply a breathable coating if it suits that wall. A coating is not a substitute for masonry repair.
How do I stop brick from crumbling every winter?
Stop the water getting into it. Fix drainage, gutters, downspouts, flashing, and grading so the brick stays dry, and cut back de-icing salt near steps and foundations. Repair failed mortar and replace badly spalled brick with a compatible soft mortar. Once the wall is sound and dry, a breathable protective finish can add another layer of defense against wind-driven rain, without trapping moisture.
Protect Your Brick the Right Way
Spalling brick does not have to mean the wall is lost, but it does need the right fix in the right order. Book a free exterior inspection and we will find the water source, assess your brick and mortar honestly, and tell you exactly what the wall needs, whether that is repair, a breathable protective system, or simply better drainage.
You get straight, no-pressure advice from a licensed, insured, veteran-owned Wisconsin crew, with a 25-year transferable warranty when a coating is the right call.
Serving Newburg, Milwaukee, Sheboygan, Waukesha, West Bend, and across Southeastern and Eastern Wisconsin.
Call or text (262) 483-2566, or request your free estimate online.
