Slab Jacking: The Comprehensive Guide to Lifting and Leveling Sunken Concrete

Concrete is a common material used for driveways, sidewalks, patios, and some home foundations. Over time, these concrete slabs can sink or become uneven due to issues like soil erosion, tree roots, or underground pipe leaks. Sunken concrete causes problems like tripping dangers, poor drainage, or costly structural damage. Instead of removing and replacing whole slabs, slab jacking offers a simple and affordable solution to lift and re-level sunken sections. This process involves injecting a grout mixture underneath to raise the concrete back into place.

What is Slab Jacking?

Slab jacking, also called concrete lifting or mudjacking, refers to injecting a special grout below sunken slabs to raise them. It’s a minimally invasive method that saves up to 70% of replacement costs while restoring concrete functionality and appearance.

Why Do Concrete Slabs Sink?

Before we dive deeper into slab jacking, it’s important to understand why concrete slabs sink in the first place. Several factors can contribute to concrete slab settlement:

• Soil Erosion: Water can wash away the soil beneath a concrete slab over time. This is especially common in areas with poor drainage or frequent heavy rainfall. As the soil erodes, it leaves voids underneath the slab, causing it to sink.
• Poor Compaction: If the soil wasn’t properly compacted before the concrete was poured, it can settle over time. This settling leads to voids beneath the slab, causing it to sink unevenly.
• Tree Roots: Large trees near concrete slabs can cause problems. As tree roots grow, they can displace the soil beneath the slab, leading to uneven settling.
• Plumbing Leaks: Underground plumbing leaks can soften the soil beneath a slab, causing it to sink. This is often seen in home foundations where plumbing runs underneath the slab.

Understanding the base reasons helps address problems at the root preventing repeat slab sinking in repaired areas.

The Slab Jacking Process

Slab jacking involves just a straightforward few steps:

• Inspection: Specialized contractors first examine the sunken slab to confirm suitability for jacking method based on observed sinking extent and perceived reasons.
• Drilling Access Holes: Small 1-2 inch holes are drilled into strategic sections on the uneven slab allowing planned lifting access underneath across the span.
• Grout Injection: Mixers pump a pressurized suspension mixture through drilled holes into the cavity below the slab, incrementally elevating the slab through controlled fill.
• Monitoring Progress: Technicians closely track slab elevation progress during pumping to ensure even surface leveling. The grouting stops once the slab is lifted to the target height.
• Patching: Upon finishing lift work, the access holes are sealed using concrete filler providing long-term closure with color matched patches.

Types of Grout Used

The injected lifting mixture features different filler formulations each with pros and cons:

• Mudjacking Grout: Traditional concrete-like grout blend using cement, soil, water and aggregates. Has heavier soil-binding properties but weight might destabilize weaker soils.
• Polyurethane Foam: Expanding lightweight foam offers adjustable lift precision without overloading ground but costs more than regular grout.
• Lime Grouting: Contains hydrated lime good for moisture control and stabilization in clay soils while gently elevating slabs.

An ideal grout selection properly balances lift function and soil condition impact.

Benefits of Slab Jacking

Slab jacking provides many perks compared to full slab replacements:

• Cost Savings: At 50-70% cheaper than reconstruction, it prevents expensive redesign and new concrete expenses.
• Non-Invasive: No demolition, dust or debris since concrete is untouched beyond a few hidden holes preserving landscapes.
• Quick: Unlike slab replacements taking weeks; injected repairs finish rapidly allowing reuse of lifted areas within one day.
• Adaptable Use: Versatile technique lifts various concrete structures like driveways and pool decking, not just sidewalks.
• Durability: Properly executed jacking lasts long term contingent preventative maintenance addressing the original soil stability issue is implemented.

When Slab Jacking Applies

Slab jacking effectively rectifies these common concrete sinking scenarios:

• Uneven Settling: Visibly raised slab sections causing tripping hazards or poor drainage.
• Foundation Slippage: Accessible spots of structural foundation slabs lifted safely within capabilities.
• Tree Root Damage: Counteracting uneven tree root heaving effects along concrete perimeter areas.
• Pool Deck Sheer: Improving pool surround safety resulting from cumulative structural and moisture loads.

Choosing Slab Jacking Contractors

Choosing the lifting specialists determines project success:

• Relevant Expertise: Seek established crews specially trained in grout injection processes over alternative crews lacking mastery handling such equipment and techniques.
• Proven Track Record: Ask how many years the contractor has actively done similar scale projects in neighborhood soil types for referenceable backgrounds instilling project assurance.
• Quality Controlling: Examine what oversight and control practices the contractor implements ensuring consistent lift results across entire slab spans with even cleanups.
• Warranties: Opt for crews guaranteeing slab lift workmanship for at least 1-2 years indicating dependability in service quality and positive outcomes.

The Cost of Slab Jacking

The cost of slab jacking varies depending on several factors, including:

• Size of the Area: Larger areas will naturally cost more to lift and level.
• Type of Grout: Different grout materials come with different price tags. Polyurethane foam, for instance, is often more expensive than traditional cement-based grouts.
• Accessibility: If the area is difficult to access, it may increase the cost of the project.
• Geographic Location: Prices can vary significantly depending on your location and local market conditions.

On average, you can expect to pay between $3 to $7 per square foot for slab jacking. However, it’s always best to get a detailed quote from a professional for your specific project.

Post Lift Slab Care

Perform routine maintenance ensuring lasting repairs:

• Moisture Control: Maintain efficient area drainage and direct water runoffs away from lifted slabs through pumps, pipes, or soil grading.
• Vegetation Control: Continuously trim invasive roots while installing physical root guards around lifted slabs preventing added subsurface turmoil.
• Damage Checks: Periodically examine lifted slab surfaces for initial signs of re-sinking like hairline cracks to enable quick intervention preventing costlier repairs later.

Conclusion

Given concrete is ubiquitous across modern construction, slab sinking issues strike countless properties eventually through inevitable mechanisms like eroding soil or protruding roots damaging functional concrete surfaces like driveways and pool decks. Previously requiring full slab replacements, injectable slab jacking processes now offer massive cost savings in repairing these issues with minimal surface disruption making aesthetic improvements and preserving landscapes intact. With lifted slabs gaining extended practical lifespans through comprehensive maintenance remediating root deterioration sources, slab jacking provides sustainable restoration for enhanced safety, drainage, and curb appeal to any sunken concrete spaces when performed by trusted crews.