What To Do When Concrete Is Sinking: A Guide For Toronto Homeowners
By: Marcrete Contracting Limited
Concrete is a durable and widely used material in Canadian homes and businesses, from driveways and sidewalks to foundations and patios. However, sinking concrete is a common problem that can lead to significant damage if not addressed promptly.
The harsh Canadian climate, with its freeze-thaw cycles and heavy rainfall, often exacerbates the issue. In this guide, we’ll explore the causes of sinking concrete, how to identify the problem, the best repair methods, and preventive measures to protect your property.
Let’s get started!
1. Understanding the Causes of Sinking Concrete
Soil Erosion
One of the most common causes of sinking concrete is soil erosion. In Canada, heavy rainfall and melting snow can wash away the soil underneath concrete slabs, leaving voids that cause the concrete to settle unevenly. Poor drainage systems can exacerbate this issue by allowing water to pool around the concrete, further eroding the supporting soil.
Poor Soil Compaction
During construction, if the soil beneath the concrete slab isn’t properly compacted, it can lead to settling over time. This is especially true in areas with loose or sandy soils. As the ground compacts naturally under the weight of the concrete and any additional loads, the slab may begin to sink or tilt.
Freeze-Thaw Cycles
Canada’s harsh winters contribute significantly to concrete settling. Water can seep into small cracks or voids in the soil beneath the concrete. When temperatures drop, this water freezes and expands, pushing the concrete upwards. As it thaws, the ground contracts, leaving gaps that cause the concrete to settle unevenly over time.
Heavy Loads
Concrete driveways and parking areas are designed to withstand significant weight, but continuous heavy loads, such as from large vehicles, can compress the soil beneath the slab. Over time, this can cause the concrete to sink, creating an uneven surface.
2. Identifying the Signs of Sinking Concrete
Uneven Surfaces
One of the most obvious signs of sinking concrete is an uneven or sloping surface. If your driveway, sidewalk, or patio no longer appears level, it’s likely that the concrete has settled unevenly. This can create tripping hazards and make your property look unsightly.
Cracks and Gaps
Cracks in the concrete or gaps between the slab and adjacent structures, such as your home’s foundation or garage, are telltale signs of sinking. These gaps can allow water to seep under the slab, exacerbating the problem and leading to further sinking.
Pooling Water
If you notice water pooling on the surface of your concrete after a rainfall, this may indicate that the slab is no longer level. Properly installed concrete should have a slight slope to allow water to drain away. When the concrete sinks, it can create low spots where water accumulates, leading to further erosion and damage.
Shifting or Leaning Structures
Structures that are attached to the concrete, such as steps or retaining walls, may shift or lean as the slab sinks. This can create safety hazards and indicate that the problem is worsening.
3. Steps to Take When You Notice Sinking Concrete
Step 1: Assess the Extent of the Damage
Before deciding on a course of action, assess the severity of the sinking. Minor sinking might only require a simple repair, while more extensive damage could necessitate professional intervention. Measure the difference in height between the sunken concrete and surrounding areas to get an idea of the extent of the problem.
Step 2: Identify the Underlying Cause
Understanding why the concrete is sinking is crucial to choosing the right repair method. For example, if poor drainage is the cause, addressing this issue will be key to preventing future problems. If the sinking is due to poor soil compaction, stabilizing the soil might be necessary.
Step 3: Consult a Professional
While some minor repairs can be handled by homeowners, consulting with a concrete repair specialist is often the best course of action. Professionals can assess the damage, identify the root cause, and recommend the most appropriate and long-lasting solution.
Step 4: Choose the Right Repair Method
Depending on the extent of the damage and the underlying cause, different repair methods may be recommended. These could range from slab jacking to polyurethane foam injection, or in severe cases, full slab replacement.
4. Popular Repair Methods for Sinking Concrete
Slab Jacking (Mudjacking)
Slab jacking, also known as mudjacking, is a common and cost-effective method for raising sunken concrete. This process involves pumping a slurry mixture of cement, sand, and water under the slab. The pressure from the slurry lifts the concrete back into place, filling any voids beneath the surface.
Polyurethane Foam Injection
Polyurethane foam injection is a more modern approach to concrete repair. This method involves injecting high-density foam beneath the concrete. The foam expands, filling the voids and lifting the slab back to its original position. Polyurethane foam is lightweight, durable, and resistant to water, making it an excellent option for long-term stability.
Concrete Replacement
In cases where the concrete has sunk significantly or is severely damaged, replacing the slab might be the best option. This involves breaking up the old concrete, preparing the ground, and pouring new concrete. While this is the most expensive option, it ensures a brand-new surface that is free from underlying issues.
Drainage Improvements
Improving drainage around your property can help prevent future sinking. This might involve installing French drains, regrading the landscape to divert water away from the concrete, or adding downspout extensions to direct water away from the foundation.
5. Preventive Measures to Avoid Sinking Concrete
Proper Soil Compaction
Ensuring that the soil is properly compacted before pouring concrete is one of the best ways to prevent future sinking. If you’re constructing a new driveway, patio, or walkway, work with a contractor who understands the importance of proper site preparation.
Effective Drainage Systems
Good drainage is essential to preventing soil erosion under your concrete. Make sure your property is graded properly so that water flows away from your concrete surfaces. Regularly clean gutters and downspouts to ensure they’re directing water away from the foundation and concrete slabs.
Regular Maintenance
Regularly inspect your concrete surfaces for cracks and other signs of damage. Seal any cracks as soon as they appear to prevent water from seeping in and causing further erosion. Additionally, consider applying a concrete sealant to protect the surface from the elements.
Limiting Heavy Loads
While concrete is durable, it’s not indestructible. If possible, limit the weight placed on your concrete surfaces by distributing loads more evenly. For example, avoid parking heavy vehicles in the same spot on your driveway.
6. When to Replace vs. Repair Sinking Concrete
Assessing the Damage
The decision to repair or replace sinking concrete depends on the extent of the damage. If the sinking is minor and the concrete is still in good condition, repair methods like slab jacking or foam injection can be effective. However, if the slab is severely cracked or has sunk significantly, replacement might be necessary.
Cost Considerations
Repairing sinking concrete is generally more cost-effective than replacing the entire slab. However, if the concrete is old or has multiple issues, replacement might offer better long-term value. Consider getting quotes for both options to determine the most cost-effective solution.
Longevity and Durability
Repair methods like polyurethane foam injection can offer long-lasting results, often extending the life of the concrete by many years. However, if the concrete is nearing the end of its lifespan or has multiple areas of damage, replacing it might be the best way to ensure durability and longevity.
Conclusion
Sinking concrete is a common issue in Canadian homes, but it doesn’t have to be a permanent problem. By understanding the causes, identifying the signs early, and choosing the right repair method, you can restore your concrete surfaces and prevent future damage. Regular maintenance and proactive measures, such as ensuring proper drainage and soil compaction, will help protect your property from sinking concrete. If you notice signs of sinking concrete, don’t hesitate to consult a professional to assess the situation and recommend the best course of action.
FAQs
- What is slab jacking, and how does it work?
- Slab jacking, also known as mudjacking, involves pumping a slurry mixture beneath a sinking concrete slab to lift it back into place. It’s a cost-effective method that fills voids and stabilises the concrete.
- How long does polyurethane foam injection last?
- Polyurethane foam injection is a long-lasting solution, with many repairs lasting over 10 years. The foam is durable, lightweight, and resistant to water, making it an excellent choice for concrete repair.
- Is it necessary to replace concrete if it’s only slightly sinking?
- Not necessarily. If the sinking is minor and the concrete is in good condition, methods like slab jacking or foam injection can effectively restore the surface without the need for replacement.
- Can I prevent concrete from sinking by sealing the surface?
- While sealing the surface can protect against water infiltration and minor cracks, it won’t prevent sinking caused by underlying soil issues. Proper soil compaction and effective drainage are key to preventing sinking.
- How much does it cost to repair sinking concrete in Canada?
- The cost of repairing sinking concrete can vary depending on the method used and the extent of the damage. Slab jacking typically costs between $500 and $1,500, while polyurethane foam injection can range from $1,000 to $3,000.
- What are the risks of ignoring sinking concrete?
- Ignoring sinking concrete can lead to further damage, including larger cracks, structural issues, and safety hazards. Over time, the problem can worsen, leading to more expensive repairs or even the need for full replacement.
- How long does the repair process for sinking concrete typically take?
- The repair process can vary depending on the method used. Slab jacking and polyurethane foam injection are typically completed in a few hours, while full replacement can take several days.
- Can sinking concrete be repaired in winter?
- Repairing concrete in winter can be challenging due to freezing temperatures. However, some methods, like polyurethane foam injection, can be performed in colder weather, although it’s generally recommended to address repairs in spring or summer.
- What are the environmental impacts of slab jacking and foam injection?
- Both slab jacking and foam injection are considered environmentally friendly options. The materials used in slab jacking are often recycled, and polyurethane foam has a low environmental impact due to its durability and efficiency.
- How can I improve drainage around my concrete slabs?
- Improving drainage involves ensuring that your property is properly graded so that water flows away from concrete surfaces. Installing French drains, extending downspouts, and regularly cleaning gutters can also help prevent water from pooling around your slabs.
If you have any questions about our article, “What To Do When Concrete Is Sinking: A Guide For Toronto Homeowners” or need concrete repair services in the Greater Toronto Area contact us at info@marcrete.ca or chat with us on LiveChat or social media.