Freeze-Thaw Saturation
Brick containing enough moisture can be damaged when that moisture freezes. Repeated wetting and freezing can progressively break down susceptible units.
Brick Deterioration Guide
Brick Spalling: Why Bricks Flake, Crack and Lose Their Faces
When the hard outer face of a brick begins to flake, scale or break away, homeowners often assume the brick is simply “old.” In reality, spalling is a symptom. The important question is what is repeatedly putting enough moisture or stress into the brick to make the face fail.
Freeze-thaw exposure is one common cause in cold climates, but it is not the only one. Concentrated water, salts, incompatible mortar, coatings, previous repairs and the brick's own durability can all influence where spalling appears and how quickly it progresses.
Spalling is material loss from the brick itself. The face may scale, pop off or break away, exposing a rougher and often more absorbent interior surface.
Do not repair spalling brick without asking why that section of wall is getting wetter or behaving differently from the masonry around it.
Common Causes
What Spalling Means
The brick itself is losing part of its surface or section.
Fired clay brick normally has a durable outer surface created during manufacturing. Spalling occurs when part of that brick breaks, flakes or delaminates away.
The damage can range from shallow scaling to the loss of most of the outer face. Some bricks develop one isolated chip. Others lose several layers over repeated winters until the unit becomes deeply recessed compared with the wall.
Spalling should be distinguished from mortar erosion. A wall can have sound bricks with failing mortar, failing bricks with relatively intact joints, or both conditions at once.
Typical signs of brick spalling
•Thin flakes or scales coming off the brick face
•A larger face shell breaking away
•Rough, recessed brick beside smoother intact units
•Loose fragments collecting below the wall
•Progressively deeper loss after successive winters
Why Brick Spalls
Most spalling involves moisture, but several mechanisms can be responsible.
The pattern around the damaged bricks often tells more than the damaged face itself.
Concentrated Water
Leaking gutters, poor sills, roof runoff, failed flashing, splashback and chronic wetting can keep one section of wall much wetter than the rest.
Salt Crystallization
Salts carried into masonry can crystallize below the surface as moisture evaporates, creating pressure that can contribute to flaking and delamination.
Hard or Incompatible Mortar
In older masonry, mortar that is substantially harder or less permeable than the brick can redirect moisture and stress into the units themselves.
Impermeable Coatings
Some paints and waterproof coatings can slow drying. If moisture enters behind them, trapped water may accelerate freeze-thaw or salt-related damage.
Brick Durability & Exposure
Brick properties, firing, absorption, orientation and exposure affect how a unit performs. Two walls on the same house can weather differently.
Look beyond the damaged brick. If spalling is concentrated below a gutter, sill, flashing detail or downspout, the water-delivery problem belongs in the repair plan.
Moisture First
Why is one patch of brick failing while the rest of the wall looks fine?
Localized spalling often means that one area is experiencing different conditions from the surrounding wall.
The damaged section may be below a leaking eavestrough, at a poorly draining sill, close to grade, beside a downspout or exposed to concentrated roof runoff. On chimneys, saturation can begin at the crown or flashing and work down into the brick below.
Replacing damaged bricks without correcting that water source can simply start the same deterioration cycle again.
Read the masonry water-damage guide →Freeze-Thaw Damage
Cold weather is most destructive when the brick is wet enough before it freezes.
NRC Canada research on brick freeze-thaw durability emphasizes two variables: the properties of the brick and the service conditions around it, especially moisture content and the temperature cycles experienced by the wall.
That is why winter alone does not explain every spalled brick. A dry wall may tolerate cold well, while a repeatedly saturated area can deteriorate much faster.
Orientation matters too. Wind-driven rain, shade, sun exposure and drying conditions can cause different elevations of the same building to experience different wetting and freezing histories.
Read the freeze-thaw masonry guide →
Winter can reveal an existing moisture problem. Fresh surface loss appearing in spring is useful evidence that the wall experienced damaging wetting and freezing conditions.
Mortar Can Matter
On older brickwork, the joint should not become harder and less forgiving than the brick.
Traditional masonry often relied on mortar joints to accommodate small movements and provide a relatively sacrificial path for weathering and drying.
National Park Service guidance warns that mortar substantially stronger than softer historic masonry can shift stresses into the masonry units and contribute to cracking or spalling. Dense mortar can also change how moisture migrates through the wall.
That does not mean every hard-looking joint caused the spalling. It means mortar compatibility should be considered when deterioration is concentrated beside previous repointing or when soft older brick is surrounded by dense, cement-rich joints.
Read the historic mortar compatibility guide →
The brick and mortar should be evaluated together. Repointing is not just filling gaps; the replacement mortar needs to suit the masonry it is intended to protect.
Peeling paint is not the same as spalling brick. But a failed low-permeability coating can be part of a moisture problem if it slows drying of already-wet masonry.
Coatings & Waterproofing
Sealing the surface is not automatically the cure for wet brick.
A wall can be damaged by water entering from above, behind or beside the masonry. If an impermeable coating is applied without controlling those sources, moisture can remain trapped within the wall.
National Park Service preservation guidance specifically cautions against treatments that trap moisture in historic masonry because freeze-thaw and salt crystallization can continue below the surface.
Breathable water-repellent treatments can have a role in selected situations, but they should be considered after the wall is dry, defects are repaired and the primary water source has been addressed.
Do the Bricks Need Replacing?
Depth, stability and location matter more than appearance alone.
Not every chipped brick requires removal, but deeply damaged units should not be treated as a cosmetic problem forever.
Monitor
May be reasonable when:
•Surface loss is shallow and stable
•No loose overhead fragments are present
•The wall remains aligned and structurally sound
•The moisture source has been corrected
Selective Replacement
Often considered when:
•A large portion of the brick face is gone
•The exposed core continues to break down
•Individual units are cracked or loose
•Matching replacement brick can be integrated properly
Broader Assessment
Needed when:
•Spalling is widespread across an elevation
•The wall is bulging or displaced
•Cracks, rusting lintels or movement accompany the damage
•The wall has repeated failed repairs
Can Spalled Brick Be Patched?
A surface patch can improve appearance, but it does not turn damaged brick back into fired brick.
Repair mortars and patching materials can be useful for selected localized defects, especially where preserving original material is important and the remaining unit is sound.
But once a substantial part of the brick has delaminated or the remaining core is weak, a thin cosmetic patch may have limited durability. The substrate, exposure and moisture source still control how the repair performs.
For ordinary residential brickwork, selective replacement is often the more straightforward long-term repair when a unit has suffered deep section loss. Historic work may justify a more conservation-focused approach.
Before patching or replacing
1Find the water source
2Determine how deep the brick has deteriorated
3Check whether neighbouring joints are compatible
4Match replacement brick by size, texture, colour range and performance
Spalling vs Other Brick Problems
Not every rough or white brick surface is spalling.
Efflorescence is a surface deposit of soluble salts. It can indicate moisture movement but does not necessarily mean the brick face has failed.
Mortar erosion is loss from the joints rather than the brick units. Repointing may be appropriate when the bricks remain sound.
Paint or coating failure may peel or blister without the brick itself losing material, although trapped moisture can contribute to deeper deterioration over time.
Cracking through brick raises a different question because it can involve movement or stress rather than surface weathering alone.
Compare common masonry damage visually →
White salts are not missing brick. Efflorescence can be an important moisture clue, but the repair decision is different from a brick that has physically lost its face.
Location changes urgency. Loose brick fragments high on a chimney or over a walkway present a falling-material concern that the same defect close to grade may not.
When to Act More Quickly
Spalling becomes more urgent when loose material or wall movement is involved.
!Loose brick pieces can fall from a chimney, parapet or upper wall
!Several adjacent bricks are deeply deteriorated
!The wall is bulging, leaning or visibly displaced
!Cracks extend through bricks and joints together
!Rust staining or movement appears around a steel lintel
!Spalling is progressing rapidly from one season to the next
Surface spalling by itself is not automatically structural. The pattern, depth, location and associated movement determine whether the issue is a localized material repair or part of a larger wall problem.
Atlantic Canada Context
Brick durability depends on both the unit and the wetting and freezing conditions around it.
Prince Edward Island, Nova Scotia and New Brunswick combine repeated freeze-thaw cycles with wind-driven rain, wet snow, coastal exposure and long periods where masonry can become wet before temperatures fall below freezing.
NRC Canada's research on freeze-thaw action in brick specifically notes that both brick properties and service conditions matter, including moisture content, wall orientation and geographical exposure.
That makes water management especially important in this region. Fixing gutters, sills, flashing, crowns, grade and failed joints can be as important as replacing the bricks that have already spalled.
Regional lesson: Cold is only part of the equation. The brick must also be wet enough for freezing to become damaging, so drainage and drying conditions belong in the diagnosis.
What to Photograph
A useful brick-spalling photo shows the damaged face and the water context around it.
Whole Wall
Show where the damage sits relative to grade, roof lines, windows, corners and downspouts.
Medium Context
Include the surrounding several feet of wall so patterns and nearby repairs can be compared.
Close-Up
Photograph the depth of face loss, cracks, loose edges and the condition of adjacent mortar joints.
Water Source
Include gutters, sills, flashing, caps, grade or any area repeatedly directing moisture toward the failed brick.
Previous Repairs
Show dense mortar patches, coatings, replacement bricks or repaired joints near the deterioration.
Seasonal Comparison
Repeat the same photographs after winter if you are monitoring whether the face loss is progressing.
Technical References
Why moisture, freezing, salts and mortar compatibility all appear in the diagnosis.
NRC Canada research on freeze-thaw action in brick explains that durability depends on both the brick itself and its service conditions, particularly moisture content and the temperature cycles experienced by the wall.
National Park Service preservation guidance explains that very hard mortar can transfer stresses into softer brick, while reduced drying and salt crystallization can contribute to cracking and spalling of masonry units.
Brick Industry Association technical guidance covers brick durability, water-penetration resistance and mortar selection, reinforcing the need to look at brick, mortar, water control and workmanship as a system rather than treating the damaged face in isolation.
NRC Canada: Freeze-Thaw Action on Brick →
NPS Preservation Brief 2: Repointing Historic Masonry →
About the Author
Prepared by Dean MacArthur, DinoMac Masonry Ltd.
Dean is a third-generation mason with more than 20 years of hands-on experience working with brick, natural stone, chimneys, foundations, repointing and masonry restoration in Prince Edward Island.
The DinoMac Masonry Knowledge Centre uses PEI field experience to explain masonry conditions that are also common across Atlantic Canada and other cold, wet climates.
Last reviewed: August 26, 2026
Brick Spalling FAQ
Common homeowner questions.
What causes brick faces to flake or pop off?
Moisture and freeze-thaw are common causes, but salts, concentrated water, hard mortar, coatings and brick durability can also contribute.
Does every spalled brick need replacing?
No. Depth, progression, stability and location matter. Deeply deteriorated or loose units are stronger candidates for replacement than light stable scaling.
Can bad mortar cause brick spalling?
It can contribute, especially where dense, hard mortar surrounds softer older brick and changes how stress and moisture move through the wall.
Can I patch the face of a spalled brick?
Sometimes for selected localized damage, but deep section loss often makes brick replacement a more durable repair.
Should I seal a wall with spalling brick?
Fix the water source and damaged masonry first. Some treatments can help in selected conditions, while unsuitable coatings may trap moisture.
Is brick spalling structural?
Not automatically. Widespread loss, bulging, displacement, deep cracks or lintel movement are reasons for a broader assessment.
Related Knowledge Centre Guides
Follow the visible symptom into the moisture, mortar or movement issue behind it.
Spalling Brick in PEI?
Photograph the damaged brick and the wall around it.
Include a wide exterior view, close-ups showing the depth of face loss, nearby gutters, sills, flashing or grade, approximate repair dimensions and the PEI property location. DinoMac can assess whether the visible problem is likely a localized brick repair or part of a broader moisture, mortar or wall condition.