A sinking concrete driveway or sidewalk is more than just an eyesore—it’s a potential safety hazard and a sign of underlying problems. Homeowners might notice this problem when water starts pooling in certain areas or when there’s a noticeable dip in the surface. While fixing it may seem daunting, you have several options for tackling the problem. This guide will walk through the causes of sinking concrete, various repair options, and preventive measures to keep driveways and sidewalks level and safe.
What Causes Sinking Concrete?
Before we dive into repair methods, be aware of why concrete surfaces sink in the first place. Identify the root cause to implement the right solution.
Soil Erosion
One of the primary culprits behind sinking concrete is soil erosion. This occurs when water washes away the soil beneath the concrete slab, creating voids that cause the surface to settle unevenly. Areas with poor drainage or those exposed to heavy rainfall are particularly susceptible to this problem.
Soil Compaction
Over time, the soil beneath concrete can settle and compact, especially if the soil wasn’t properly prepared before the concrete was poured. This can lead to uneven settling and, ultimately, a sinking driveway or sidewalk. Ensuring that soil is compacted properly before pouring concrete mitigates the risk.
Tree Root Decay
Large tree roots growing beneath concrete surfaces can cause problems in two ways. As they grow, they can lift the concrete, creating uneven surfaces. Conversely, when the roots decay over time, they leave voids that can cause the concrete to sink.
What Are the Signs of a Sinking Concrete Driveway or Sidewalk?
Identifying the problem early can save you time and money in the long run. Here are some telltale signs that a concrete surface may be sinking:
- Visible dips or depressions in the surface
- Cracks forming, especially along edges
- Water pooling after rain
- Gaps between concrete and adjacent structures
- Uneven surfaces that create tripping hazards
Ways To Repair Sinking Concrete
Once you’ve identified you have sinking concrete, you have several methods to repair it. The choice depends on the severity of the problem and your budget.
Mudjacking
Mudjacking, or slabjacking, is a popular method for lifting sunken concrete. It involves drilling small holes in the concrete and pumping a mixture of cement, soil, and other additives underneath the slab to raise it back to its original position.
The process typically takes a few hours and can be cost effective for larger areas. However, it adds significant weight to the underlying soil, which may not be appropriate for all situations. Consult with a professional to help determine if mudjacking is right for your property conditions.
Polyurethane Foam Injection
A more modern approach to lifting concrete is using polyurethane foam injection. This method involves injecting expanding foam beneath the concrete slab, which fills voids and lifts the concrete back into place.
Polyurethane foam is lighter than the mud slurry used in mudjacking, making it a good option for soils that may not support additional weight. It also sets quickly, allowing for almost immediate use of the repaired area. This method is especially useful when time and minimal disruption are crucial considerations.
Concrete Resurfacing
Concrete resurfacing can be an effective solution for minor sinking or unevenness. This method involves applying a thin layer of concrete over the existing surface to level it out. While it doesn’t address the underlying cause of sinking, it can improve the appearance and functionality of mildly affected areas.
Concrete resurfacing provides a fresh look and can be a more budget-friendly option for homeowners with minor leveling issues, but take into account whether the underlying problem could worsen over time.
Complete Replacement
In severe cases where the concrete is extensively damaged. or the underlying issues are significant, a complete replacement may be necessary. While this is the most expensive and time-consuming option, it allows for proper preparation of the underlying soil and ensures a long-lasting solution.
A complete replacement offers the opportunity to address preexisting conditions and reinforce the stability of the new installation.
DIY Vs. Professional Repair
Homeowners often wonder whether they can tackle concrete repair as a DIY project. While skilled DIY enthusiasts can do some minor repairs, most sinking concrete issues need professional expertise.
When To DIY
You can sometimes address minor cracks or small areas of unevenness with DIY methods. For example, homeowners can fill small cracks with concrete caulk or patching compound. Self-leveling and resurfacing small areas are well within the realm of a weekend project.
When To Call a Professional
For more significant sinking or when the cause is unclear, it’s best to consult a professional. They have the equipment and expertise to accurately diagnose the underlying cause of sinking, implement advanced repair methods such as mudjacking or foam injection, and ensure the repair addresses the root problem, not just the symptoms.
Professional intervention guarantees a comprehensive approach, preventing future complications and securing the longevity of your concrete surfaces.
Preventive Measures
Preventing concrete from sinking is often easier and more cost effective than repairing it. Here are some steps homeowners can take to maintain their concrete surfaces:
Proper Drainage
Make sure concrete areas have proper drainage by grading the soil away from the concrete, installing gutters and downspouts on your home to direct water away from the foundation, or creating drainage channels in areas prone to water accumulation.
Proper drainage solutions reduce erosion from water and help keep concrete level.
Tree Management
You’ll need to manage trees that are near concrete. Consider how planting new trees, with their root spread, will affect nearby concrete, and use root barriers as needed. If you’re not attached to a tree, it might be worth removing it if there’s a chance it might damage the concrete.
Cost Considerations
The cost of repairing a sinking concrete driveway or sidewalk can vary widely depending on the method used and the extent of the damage. Here’s a general overview:
- Mudjacking: $3 to $6 per square foot
- Polyurethane foam injection: $5 to $25 per square foot
- Concrete resurfacing: $3 to $9 per square foot
- Complete replacement: $4 to $8 per square foot
Get multiple quotes from reputable contractors and consider the long-term benefits of each repair method when making a decision. Weighing costs against potential long-term benefits when deciding on a fix.
Further Information
- Sidewalk Damaged by Tree Roots (article)
- How to Fix a Sinking Asphalt Driveway (article)
- How to Repair Cracks and Resurface a Concrete Driveway (video/article)
- How to Seal Expansion Joints in a Concrete Driveway (video)
