In this guide, you’ll learn:
- How Ontario’s weather and climate wear down masonry over time
- The most common signs of weather-related masonry damage
- Why changing climate patterns make restoration more important than ever
- What professional masonry restoration and maintenance can do to save and extend your structure
This article is written for property owners in the GTA and surrounding areas, and tailored to the conditions that masonry faces in cities like Vaughan, Toronto, Brampton, Mississauga, Richmond Hill, Aurora, Ajax, Caledon, and beyond.
1. How Weather & Climate Impact Masonry in Ontario
Masonry is durable, but it is not invincible. Every brick and mortar joint constantly absorbs and releases moisture, expands and contracts with temperature swings, and weathers under sun, wind, and pollutants. Over years and decades, this slow, constant stress leads to visible damage — and sometimes hidden structural problems.
In the GTA, masonry faces a particularly demanding climate:
- Average annual precipitation: Around 845 mm (33.3 inches) of rain and melted snow each year, with precipitation spread across all months
(Climate-Data.org). - Average annual snowfall: Approximately 121.5 cm (48 inches) in Toronto, often higher in nearby areas
(Wikipedia: Geography of Toronto). - Freeze-days: More than 100 days per year with lows at or below 0 °C, creating frequent freeze–thaw cycles
(CurrentResults.com). - Summer heat: Regular summer highs above 25 °C, with many days reaching 30 °C or more, plus humidity
(CurrentResults.com). - Humidity: Summer relative humidity often in the 60–70%+ range
(TimeAndDate.com).
Taken together, this means masonry in Ontario spends the year cycling between wet and dry, frozen and thawed, expanded and contracted. This is exactly the kind of environment where masonry problems grow quietly until they become obvious and expensive.
1.1 Moisture & Rain Exposure
Brick, stone, and mortar are naturally porous. They act a bit like a sponge, pulling in water from rain, snowmelt, and surface runoff. In a climate where there’s no true dry season, like the GTA, this moisture exposure never really stops.
When rainwater is allowed to soak into masonry again and again:
- Moisture travels deeper into walls and foundations.
- Salts inside the masonry dissolve and move, eventually forming white surface deposits (efflorescence).
- Mortar softens, erodes, and loses its bond.
- Interior damp patches can develop behind walls and around windows.
Over time, moisture is often the starting point for nearly every other masonry issue. Many contractors and restoration specialists note that long-term water exposure is the root cause of spalling, cracking, efflorescence, and mold growth in masonry
1.2 Freeze–Thaw Cycles
Freeze–thaw damage is one of the biggest threats to masonry in Ontario. When water gets into tiny pores and hairline cracks, then freezes, it expands by roughly 9%.
That expansion puts pressure on the surrounding brick or mortar. When it thaws, it shrinks again. Multiply this by dozens of freeze–thaw cycles each winter, and you get serious stress.
Common results of freeze–thaw cycles include:
- Surface flaking and spalling of brick faces
- Chunks of brick or stone popping off
- Widening of small cracks into visible fractures
- Loose mortar joints and gaps between units
Contractors across North America highlight freeze–thaw as a leading cause of masonry deterioration in cold climates In a region with more than 100 freeze-days a year, it’s not a question of whether freeze–thaw will affect masonry, but how soon and how severely.
1.3 Heat, Sun & Thermal Expansion
Winter isn’t the only season that matters. In summer, dark brick facades and stone surfaces can heat up dramatically in direct sunlight. As masonry heats, it expands. When the temperature drops at night, it contracts. Over and over, this thermal cycling puts joints and materials under stress.
This can lead to:
- Fine cracks around window heads and corners
- Separation between bricks and mortar at exposed faces
- Deterioration of old sealants and caulking
- Increased surface porosity that allows even more moisture in
Long-term UV exposure can also fade brick or stone and weaken some surface treatments, especially if cheap or incorrect coatings were used
1.4 Wind, Storms & Extreme Weather
Strong winds and storm events can accelerate existing problems. Wind-driven rain is more likely to be forced into small cracks and open joints. During heavy storms, water may hit walls at higher pressure or run down surfaces in sheets, overloading drainage paths.
Over time, this can cause:
- Increased erosion of mortar in exposed areas
- Water infiltration around corners, parapets, and chimneys
- Accelerated degradation where flashing or detailing is poor
1.5 Humidity & Long-Term Damp Conditions
Summer humidity in the GTA often stays high, especially after rain. When air is humid, wet masonry takes longer to dry. This keeps bricks and mortar damp for extended periods, giving salts more time to migrate and crystals more time to grow inside pores.
Persistent humidity and dampness can:
- Encourage mold and algae growth on shaded walls
- Promote efflorescence and subflorescence (salt crystallization inside the masonry)
- Slow down the drying of basements and foundations
- Contribute to musty odors and indoor air-quality issues
For masonry in contact with soil or poorly drained areas, this combination of humidity and moisture can be especially damaging over time.
2. Common Types of Masonry Damage Caused by Weather
Many masonry failures look different on the surface, but most trace back to the climate-related stresses described above. Here are the issues homeowners and building owners most often see in Ontario.
2.1 Cracks in Brick, Stone & Mortar
Cracks can appear:
- Vertically, along the height of walls
- In a stair-step pattern along mortar joints
- Horizontally near window lintels or mid-wall
- At corners and parapets
Some cracks are mostly cosmetic; others can indicate structural movement.
Moisture entering cracks can freeze, expand, and widen them, or travel deeper into the wall where it affects interior finishes and structural elements.
2.2 Spalling, Flaking & Surface Scaling
Spalling is when the face of a brick or stone begins to chip, flake, or break away. You may see shallow craters on the brick face, or entire faces popping off. This problem is strongly associated with freeze–thaw action in wet masonry. Left unaddressed, spalling can spread across a wall and eventually require larger-scale rebuilding.
2.3 Mortar Joint Deterioration
Mortar is usually softer than the brick or stone it holds. That’s intentional — mortar is meant to be sacrificial so the units themselves last longer. But once mortar has eroded, cracked, or washed out, the masonry becomes vulnerable.
Signs of mortar joint deterioration include:
- Gaps and voids between bricks or stones
- Powdery or crumbling mortar that can be brushed out by hand
- Loose bricks or stones that shift when touched
At this stage, water can easily enter and travel through the wall, leading to interior dampness, rusting of embedded metals, and further freeze–thaw damage.
2.4 Efflorescence (White Salt Deposits)
Efflorescence looks like a white, powdery or crystalline deposit on the surface of masonry. It forms when moisture dissolves salts inside the masonry and then evaporates at the surface, leaving the salts behind (explained in more detail on
Wikipedia). Efflorescence itself is not always structurally damaging, but it is a symptom of water movement — and that’s what needs to be addressed. Persistent or heavy efflorescence can also stain and disfigure brickwork.
2.5 Bulging Walls & Loose Units
In more serious cases, long-term moisture, freeze–thaw action, and deteriorated mortar can lead to:
- Bulging or bowing sections of wall
- Out-of-plane movement around windows or openings
- Loose bricks or stones that are no longer well bonded
These conditions can be structural safety concerns and require prompt professional assessment and repair.
3. Why Climate Trends Make Masonry Care More Critical
Across Canada, many regions are seeing:
- More frequent freeze–thaw events
- Heavier rainfall events in shorter periods
- Wetter winters and unpredictable weather swings
- Longer warm seasons with sustained humidity
For masonry, this means:
- More cycles of expansion and contraction each year
- More time spent in a saturated or damp state
- Higher risk of moisture and salt-related damage
Many existing buildings in the GTA were not originally designed with these future conditions in mind. As climate patterns evolve, proactive masonry inspection, restoration, and maintenance are no longer optional — they are part of responsible building ownership.
4. How Professional Masonry Restoration Protects Your Property
The good news: most weather-related masonry issues can be controlled, slowed, or reversed if they are caught in time and treated correctly. Professional restoration teams follow proven methods to keep your brick and stone performing in a demanding climate.
4.1 Thorough Masonry Inspection & Assessment
Every effective restoration project starts with a careful inspection.
Specialists look for:
- Cracks and movement patterns
- Spalled or delaminated bricks
- Mortar erosion, gaps, and failed joints
- Efflorescence and moisture staining
- Signs of interior damp or mold near exterior walls
- Failed or missing flashings, drip edges, and sealants
4.2 Repointing / Tuckpointing Mortar Joints
When mortar is deteriorated, it is carefully removed to a specific depth and replaced with new, compatible mortar in a process called repointing or tuckpointing. This is one of the most powerful ways to extend the life of masonry in a harsh climate.
Correct repointing:
- Restores the bond between bricks or stones
- Helps keep water out of the wall
- Improves structural stability
- Refreshes the visual appearance of the façade
Using the wrong mortar mix, however, can cause damage — another reason to rely on experienced professionals who understand historic and modern masonry behavior.
4.3 Repairing or Replacing Damaged Bricks & Stones
Severely cracked, spalled, or broken bricks and stones are often best replaced. Restoration specialists will source units that match the original size, texture, and color as closely as possible and use techniques designed to integrate them structurally and visually. Choosing the wrong replacement materials or methods is a common mistake in DIY or low-quality repairs.
4.4 Waterproofing with Breathable Sealants
In climates with frequent rain and freeze–thaw cycles, a high-quality, breathable water-repellent treatment can be an excellent protective measure. These coatings help reduce water absorption while still allowing moisture vapor to escape. Breathability is critical: non-breathable sealers can trap moisture inside bricks and stones, actually making freeze–thaw damage worse.
Guidance documents such as National Park Service material on masonry deterioration emphasize using vapor-permeable systems for most masonry(NPS Masonry Deterioration Glossary).
A proper waterproofing strategy may also include:
- Ensuring gutters and downspouts move water away from walls
- Improved grading around foundations
- Repairing flashing around windows, doors, and roof intersections
4.5 Maintaining Expansion Joints & Movement Joints
Expansion joints are designed to absorb thermal movement so that masonry can expand and contract without cracking. In older buildings, joints may be missing, undersized, or filled with hardened material that no longer flexes.
Restoration may involve:
- Renewing failed sealant in joints
- Adding missing joints in long wall runs
- Ensuring joints are detailed to handle anticipated movement
Keeping these joints functional is one of the best defenses against climate-driven cracking and displacement.
4.6 Safe Masonry Cleaning & Surface Treatment
When cleaning masonry, aggressive methods like sandblasting or very high-pressure washing can strip away protective surface layers, making the material more vulnerable to moisture and freeze–thaw damage. Historic and technical resources repeatedly caution against such methods.
Professional cleaning typically uses:
- Low-pressure water washing
- Soft brushes and controlled agitation
- Specialized masonry detergents or poultices
- Targeted chemical treatments for efflorescence or biological growth
The goal is to improve appearance without sacrificing durability.
4.7 Seasonal & Annual Maintenance Programs
In a climate as active as Southern Ontario’s, one-time repairs are not enough. Regular checkups allow small issues to be addressed long before they become big ones.
Smart times to schedule inspections include:
- Early spring: After freeze–thaw season, to check for new cracks, spalling, and moisture damage.
- Late summer: After heat and storms, to assess expansion joints, sealants, and surface conditions.
- Before major renovations: To ensure existing masonry can handle added loads or changes.
A consistent maintenance plan extends the life of your masonry and protects your investment in your building.
5. What All This Means for GTA Homeowners & Building Owners
When you combine:
- Year-round precipitation
- More than 100 freeze-days each year
- Hot, sunny summers
- High humidity and strong storms
…you get one of the most challenging environments for masonry.
Ignoring small signs of damage can quickly lead to much more serious problems, including:
- Water infiltration into basements and interiors
- Mold growth and indoor air-quality issues
- Structural cracking or wall movement
- Falling masonry hazards
- Energy loss through damp and damaged walls
- Expensive large-scale repairs or rebuilding
On the other hand, homeowners who invest in timely restoration and ongoing maintenance typically enjoy:
- Longer-lasting brick, stone, and mortar
- Improved structural safety and stability
- Better curb appeal and higher property value
- Dryer, healthier interior spaces
- Peace of mind through every season
6. How Solid Core Construction Helps Protect Your Masonry
Solid Core Construction works with homeowners and property managers across the GTA and surrounding Ontario communities to diagnose, repair, and prevent masonry damage caused by weather and climate.
From our base in Vaughan, we serve areas such as:
- Vaughan
- Toronto
- Brampton
- Mississauga
- Richmond Hill
- Aurora
- Ajax
- Bradford
- Caledon
- And many surrounding communities in Southern Ontario
Our masonry-related services include:
- Masonry inspections and condition assessments
- Brick and stone work
- Repointing and tuckpointing of mortar joints
- Waterproofing and breathable sealant application
- Structural masonry work
- Exterior façade restoration
Whether you are dealing with visible cracking, spalling bricks, efflorescence, or you simply want a professional opinion on the health of your masonry, our team can recommend a restoration plan tailored to your building and its exposure conditions.
To learn more about our services or request a consultation, visit
solidcoreconstruction.ca.
Conclusion
Weather and climate are always working on your masonry — quietly, steadily, and relentlessly. In Ontario’s demanding environment, where rain, snow, freeze–thaw cycles, heat, and humidity all play a role, brick and stone structures need knowledgeable care to perform at their best.
By understanding how climate affects masonry, recognizing early warning signs, and partnering with a qualified restoration contractor, you can:
- Protect your home or building from water and structural damage
- Preserve the character and beauty of your brick and stone
- Extend the life of your masonry for decades
If your property is in the GTA or a nearby Ontario community, and you’re concerned about what the weather may be doing to your masonry, reach out to Solid Core Construction for a professional assessment and restoration plan tailored to your building and your climate.
