Frost Heave:
Causes, Warning Signs, and How to Protect Your Home in Oregon and Washington

Cold winters in the Pacific Northwest don’t just affect roads and landscapes; they can also impact the stability of your home. One of the most common cold-weather ground movement issues homeowners face in Oregon and Washington is frost heave. While it often starts subtly, frost heave can lead to cracked concrete, uneven floors, and serious foundation problems if left unaddressed.

At TerraFirma Foundation Systems, our foundation and concrete specialists have spent decades repairing frost-heave-related damage across Oregon and Washington. This guide explains what frost heave is, why it happens, how to identify it early, and what homeowners can do to prevent or repair it, based on real-world field experience, not theory.

Frost heave is the upward movement of soil caused by freezing ground conditions. When water in the soil freezes, it expands and forms ice lenses beneath the surface. These ice lenses push soil upward, lifting anything resting on it, such as concrete slabs, foundations, sidewalks, and fence posts.

Frost heave is not caused by cold temperatures alone. It occurs when three conditions exist at the same time:

• Frost-susceptible soil
• Sufficient moisture
• Freezing temperatures

Remove any one of these elements, and frost heave cannot occur.

Frost heave is the upward movement of soil caused by freezing ground conditions. When water in the soil freezes, it expands and forms ice lenses beneath the surface. These ice lenses push soil upward, lifting anything resting on it—such as concrete slabs, foundations, sidewalks, and fence posts.

Frost heave is not caused by cold temperatures alone. It occurs when three conditions exist at the same time:

1. Frost-susceptible soil
2. Sufficient moisture
3. Freezing temperatures

Remove any one of these elements, and frost heave cannot occur.

In addition, the Pacific Northwest often experiences freeze-thaw cycles, where temperatures fluctuate above and below freezing. These cycles worsen frost heave by repeatedly expanding and contracting soil, increasing movement over time.

From our experience at TerraFirma, frost heave most commonly affects:

• Driveways and sidewalks
• Garage slabs and porches
• Foundations with poor drainage
• Fence posts and retaining walls
• Crawl spaces and slab-on-grade homes

In addition, the Pacific Northwest often experiences freeze-thaw cycles, where temperatures fluctuate above and below freezing. These cycles worsen frost heave by repeatedly expanding and contracting soil, increasing movement over time.

From our experience at TerraFirma, frost heave most commonly affects:

• Driveways and sidewalks
• Garage slabs and porches
• Foundations with poor drainage
• Fence posts and retaining walls
• Crawl spaces and slab-on-grade homes

When surface temperatures drop below freezing, a frost front moves downward through the soil. As it progresses, moisture from deeper soil layers is drawn upward toward the freezing zone. This moisture freezes and forms ice lenses, which expand and lift the soil above them.

Contrary to popular belief, frost heave is not a one-time event. It happens gradually and gets worse each winter if conditions remain unchanged. Homes with poor drainage or high groundwater levels are especially vulnerable.

Identifying frost heave early can prevent costly structural repairs. Diagnosis involves recognizing both exterior and interior warning signs and understanding how seasonal ground movement affects concrete and foundations.

Exterior Warning Signs

• Uneven or lifted concrete slabs
• Cracks in driveways, patios, or sidewalks
• Raised edges or sunken sections of concrete
• Fence posts or deck supports tilting or lifting
• Gaps forming between soil and foundation walls

Interior Warning Signs

• Doors or windows sticking seasonally
• Cracks in drywall or ceilings
• Sloping or uneven floors
• Separation between walls and floors

At TerraFirma, we often see frost heave misdiagnosed as settlement. The key difference is seasonality; frost heave movement often worsens in winter and stabilizes in warmer months, while settlement is typically progressive year-round.

Exterior Warning Signs

• Uneven or lifted concrete slabs
• Cracks in driveways, patios, or sidewalks
• Raised edges or sunken sections of concrete
• Fence posts or deck supports tilting or lifting
• Gaps forming between soil and foundation walls

Interior Warning Signs

• Doors or windows sticking seasonally
• Cracks in drywall or ceilings
• Sloping or uneven floors
• Separation between walls and floors

At TerraFirma, we often see frost heave misdiagnosed as settlement. The key difference is seasonality—frost heave movement often worsens in winter and stabilizes in warmer months, while settlement is typically progressive year-round.

Foundation Damage

Repeated upward pressure can cause foundation walls or slabs to crack, shift, or become uneven. Over time, this can compromise the structural integrity of the home and allow allowing water intrusion.

Concrete Failure

Driveways and walkways affected by frost heave often crack and separate. These uneven surfaces become safety hazards and reduce curb appeal.

Landscaping and Structural Elements

Retaining walls, fences, and decks can lose stability if their footings are above the frost line. Repeated lifting and settling eventually weaken these structures.

Foundation repairs are significantly more expensive than preventative solutions, which is why early evaluation is critical.

Foundation Damage

Repeated upward pressure can cause foundation walls or slabs to crack, shift, or become uneven. Over time, this can compromise the structural integrity of the home and allow allowing water intrusion.

Concrete Failure

Driveways and walkways affected by frost heave often crack and separate. These uneven surfaces become safety hazards and reduce curb appeal.

Landscaping and Structural Elements

Retaining walls, fences, and decks can lose stability if their footings are above the frost line. Repeated lifting and settling eventually weaken these structures.

Foundation repairs are significantly more expensive than preventative solutions, which is why early evaluation is critical.

Improve Drainage

Excess moisture is the biggest contributor to frost heave. Effective solutions include:

• Downspout extensions directing water away from the home
• French drains or surface drainage systems
• Downspout extensions directing water away from the home

Use Frost-Resistant Materials

When replacing soil near foundations or slabs, use gravel or well-draining aggregate instead of clay or silt. These materials reduce water retention and limit ice formation.

How to Prevent Frost Heave in Concrete Slabs

Preventing frost heave in concrete slabs requires proper base preparation, drainage control, and frost-resistant materials. Slabs should be installed over well-draining gravel, with water directed away from the slab perimeter to prevent moisture buildup beneath the concrete.

Improve Drainage

Excess moisture is the biggest contributor to frost heave. Effective solutions include:

• Proper grading away from the foundation
• French drains or surface drainage systems
• Downspout extensions directing water away from the home

Use Frost-Resistant Materials

When replacing soil near foundations or slabs, use gravel or well-draining aggregate instead of clay or silt. These materials reduce water retention and limit ice formation.

Build Below the Frost Line

Fence posts, deck footings, and structural supports should be installed below the regional frost depth. In Oregon and Washington, frost depth varies by location, making professional guidance important.

Even with preventative measures, frost heave can still occur, especially in older homes. Repair strategies depend on the severity and location of the damage.

Concrete Repair

Minor slab lifting may be addressed through resurfacing or leveling. However, recurring frost heave often requires soil correction and drainage improvements beneath the slab.

Foundation Repair

Cracked or shifting foundations should be evaluated by specialists. Depending on conditions, repairs may include:

• Epoxy crack injection
• Structural reinforcement
• Pier systems to stabilize and re-level affected areas

Landscape and Structural Corrections

Tilted fences, retaining walls, and deck supports may need repositioning or deeper footings to prevent future movement.

DIY fixes rarely address the root cause of frost heave. Without correcting soil and moisture conditions, damage is likely to return.

If you notice recurring cracks, uneven concrete, or seasonal movement around your home, it’s time to consult a professional. TerraFirma Foundation Systems has extensive experience diagnosing frost heave versus settlement and designing long-term solutions tailored to Pacific Northwest soil conditions.

Frost heave problems rarely fix themselves and early intervention can save thousands in future repairs.

We offer professional evaluations, clear explanations, and proven repair solutions designed to stop frost heave at the source—not just cover up the symptoms.

Schedule a foundation or concrete evaluation today and get expert guidance you can trust.