What Causes Concrete Spalling in Parking Garages?

If you’ve noticed flaking, cracking, or chunks of concrete breaking away in your parking garage, you may be dealing with concrete spalling. This common but serious issue affects many garages in cold-weather regions like New England.

So what causes concrete spalling in garages?

The primary causes are moisture, road salt, and corrosion of embedded steel reinforcement — especially when combined with freeze-thaw cycles.

Understanding why it happens is the first step toward preventing costly repairs.

What Is Concrete Spalling?

Concrete spalling occurs when the surface of concrete begins to crack, chip, or break apart. It can appear as:

• Surface flaking or scaling
• Deep cracking
• Exposed rebar
• Falling concrete fragments

Left untreated, spalling can compromise both safety and structural integrity.

Road Salt Is a Major Contributor

In winter, vehicles carry road salt and brine into parking garages. Salt penetrates porous concrete and accelerates chemical reactions inside the slab.

Over time, salt:

• Weakens the concrete matrix
• Promotes corrosion of reinforcing steel
• Breaks down protective coatings

This is why garages in northern climates experience more severe spalling than those in warmer regions.

The Freeze-Thaw Cycle Makes It Worse

Concrete absorbs moisture. When temperatures drop below freezing, trapped water expands as it turns to ice. When it thaws, it contracts again.

This repeated expansion and contraction creates internal stress within the concrete, leading to:

• Surface cracking
• Delamination
• Progressive spalling

Salt lowers the freezing point of water, increasing how deeply moisture penetrates before freezing — worsening the damage.

Corrosion of Reinforcing Steel

Inside most concrete parking garages is steel reinforcement (rebar). When salt and moisture reach the steel, corrosion begins.

As steel corrodes, it expands. This expansion pushes outward against the surrounding concrete, causing it to crack and break away.

Once rebar is exposed, deterioration accelerates quickly.

Poor Drainage and Standing Water

Garages that have inadequate drainage or clogged floor drains allow water and salt to pool on surfaces.

Standing water increases:

• Moisture absorption
• Freeze-thaw damage
• Corrosion risk

Regular cleaning and drain maintenance help prevent this cycle.

Lack of Routine Cleaning

When salt and sand are allowed to sit on garage surfaces for months, they continue to attack concrete long after winter ends.

Without routine pressure washing:

• Salt remains embedded in joints and cracks
• Corrosion continues unchecked
• Small surface damage becomes structural deterioration

Preventive maintenance is far less expensive than structural repairs.

How to Prevent Concrete Spalling

The best defense against spalling includes:

• Post-winter salt removal
• Regular professional pressure washing
• Proper drainage maintenance
• Routine inspections
• Timely repair of small cracks

Proactive maintenance extends the life of your parking structure.

Final Answer: What Causes Concrete Spalling in Garages?

Concrete spalling in parking garages is primarily caused by moisture, road salt, freeze-thaw cycles, and corrosion of reinforcing steel. Without regular cleaning and maintenance, these factors can lead to significant structural damage.

Protecting your garage starts with routine cleaning and salt removal.

Contact OFF THE WALL today to schedule professional parking garage cleaning and help prevent long-term structural deterioration.