Frost heaving isn’t just a problem for lawns and gardens; it can also pose serious risks to your home’s basement foundation. This natural process, caused by the freezing and expansion of water in the soil, can cause upward movement and shift and crack the very structures meant to support your home. In fact, frost heave is the reason many basements exist. "In some parts of the country, the frost depth can be eight feet, and footings need to extend below that level to resist frost heave," explains Bob Brown, a certified Foundation Repair Specialist and author of 'Foundation Repair Secrets: Learn How to Protect Yourself and Save Thousands.' "This explains why basements are common in very cold areas. If you are digging eight feet for frost depth, you might as well dig a bit more and give yourself a basement!"
Simple foundation inspections, understanding the signs of frost heave, and what preventative measures you can take can save you from costly repairs and protect your home’s stability for years to come.
What causes frost heaves?
Frost heaves occur when water in soil freezes and causes upward expansion. While this cycle of freezing is a natural part of seasonal change in colder climates, it becomes a problem when the soil beneath a home’s foundation walls moves unevenly.
"Some types of soil absorb more moisture than others, and soils with more moisture in them will experience greater movement due to frost heave," shares Brown. "If there is an impenetrable layer below a certain depth, the moisture will gather on top of it as it cannot penetrate below. As the water in these soils freezes, it crystallizes and expands. Since it is constrained on the bottom and on the sides, the easiest way to expand is up and, if your footings on the perimeter of your building are not sufficient depth, they will start to experience an upward movement." These forces can cause foundation wall cracks, tilting, or even lift sections of the foundation over time, leading to visible structural damage both inside and outside the home.
He adds, "As temperatures warm back up, the crystallization melts, and the water returns to its liquid state, the expansion recedes and downward movement will occur in footings that had experienced frost previously. This can result in cyclical movements each year with warming and cooling."
Shallow foundations are particularly vulnerable, as they are more likely to be impacted by the expansion and contraction of the upper layers of soil. Even a small amount of movement can result in misaligned doors and windows, cracked walls, or sagging floors.
Signs of Frost Heave Damage
If you suspect frost heave might be affecting your concrete foundation, do regular inspections and look out for these warning signs:
- Cracks in walls or floors: Foundation cracks, or horizontal or stair-step cracks in the basement walls or exterior walls can indicate shifting.
- Doors and windows that stick: Movement in the foundation can cause frames to warp, making it difficult to open or close them.
- Uneven floors or sloping floors: A telltale sign that the underlying foundation has shifted.
- Gaps between walls and ceilings: Visible separations often point to structural movement caused by soil or foundation upheaval.
- Damage to outdoor structures: Look for tilting steps, patios, or walkways near the home. They may signal underlying frost heave issues in areas close to the foundation.
While signs of movement tend to appear and minimize between seasons, if you notice issues, it’s important to act quickly to address the problem before it worsens. "The most important thing to do is to call a forensic geotechnical engineer for a thorough investigation," notes Brown. "This is far better than calling a Foundation Repair contractor who will have an agenda to sell you products and services. Although the repair contractor will offer their “analysis” free of charge, it will be offered by a commissioned salesperson who wants to earn a commission.
How to Prevent Frost Heave Around Your Foundation
"You can minimize this damage by directing the moisture away from the area that would influence footing movement," notes Brown. To protect your home’s foundation from frost heave, focus on reducing soil moisture and improving proper drainage around your property. Preventative steps include:
- Grade the landscape: Ensure the ground slopes away from your home to direct water away from the foundation.
- Install a drainage system: French drains or downspout extensions to carry water safely away are good drainage solutions. "[Don't] don’t make the fatal mistake of connecting the gutters to the French drains," cautions Brown. "That will create an injection system of water into the soils."
- Insulate the foundation: Adding rigid foam insulation around the foundation can regulate soil temperature and reduce freeze-thaw cycles.
- Use frost-resistant footings: For new construction, deep foundation footings that extend below the frost depth can prevent movement.
- Keep gutters clean: Properly functioning gutters prevent water from pooling near the foundation.
- Avoid overwatering: Be mindful of watering practices around the home, especially during late fall.
Can frost heave damage be repaired?
Yes, frost heave damage can be repaired, but the methods depend on the extent of the issue. Minor cracks may be sealed with epoxy, while more significant damage could require foundation underpinning or leveling. It’s best to consult a specialist in foundation repair solutions for an assessment of damage, structural integrity, and possible preventive measures.
Is frost heave only a problem in cold climates?
Frost heave is most common in areas with freezing temperatures, but it can still occur wherever ground freezing happens. Depth of frost penetration, type of soil, and foundation type all factor in. Homes in regions with expansive soils, or poorly draining soil types, like clay soils, or fluctuating temperatures during the winter months are especially at risk.
