Use This Calculator to find Retaining Wall Cost

The material chosen is often the most significant cost driver. Different materials vary widely in price, installation difficulty, lifespan, and aesthetic appeal.

Pros and Cons of Common Materials:

• Timber:
  • Pros: Relatively inexpensive initially, good for DIY on smaller walls, natural look.
  • Cons: Shorter lifespan, susceptible to rot and pests, limited height potential without significant engineering.
• Concrete Blocks (CMU & SRW):
  • Pros: Strong, durable, versatile appearance options (especially SRWs), moderate cost, good for DIY or professional install.
  • Cons: Can be less natural looking than stone/timber, requires proper footing and drainage.
• Poured Concrete:
  • Pros: Extremely strong and durable, good for tall or critical walls.
  • Cons: Utilitarian appearance unless faced, requires extensive formwork, professional installation recommended, higher cost.
• Natural Stone:
  • Pros: Beautiful, unique aesthetic, extremely long-lasting, integrates well with natural landscapes.
  • Cons: Expensive materials, labor-intensive installation, requires skilled masons.

Wall Dimensions (Length, Height, and Total Square Footage)

The overall size of the wall is a primary cost factor. Costs are typically calculated per square foot (Length x Height).

• Length: A longer wall naturally requires more materials and labor.
• Height: Taller walls require more robust engineering, deeper footings, more excavation, potential reinforcement (like geogrid), and significantly more material and labor per linear foot. Walls over 3-4 feet often have stricter permit requirements and may necessitate professional engineering plans.

Site Conditions and Preparation

The existing condition of the installation site dramatically affects the cost.

• Slope Severity: Steeper slopes require more excavation, potentially more terracing, and present greater construction challenges, increasing labor time and cost.
• Soil Type: Poorly draining clay soil or rocky soil requires more extensive excavation, potentially specialized equipment, and specific backfill materials (like clean aggregate), adding to the cost compared to stable, easy-to-dig loam.
• Accessibility: Sites with difficult access for machinery (excavators, skid steers) or material delivery (narrow paths, backyard locations) will incur higher labor costs due to manual work or smaller, less efficient equipment.
• Excavation: Clearing vegetation, digging the trench for the footing and drainage system, and removing excess soil all contribute to the cost. Difficult conditions raise this cost component.

Labor Costs (DIY vs. Professional)

Labor is a substantial part of the total cost, often ranging from 50% to 70% of the project price.

• DIY: Eliminates direct labor costs but requires significant time, physical effort, tool rental/purchase, and construction knowledge (especially regarding footings and drainage). Mistakes can be costly to fix. Best suited for smaller, simpler walls (e.g., timber or block walls under 3 feet).
• Professional Installation: Ensures proper construction techniques, adherence to codes, efficiency, and handling of complex site issues. Costs vary based on:
  • Location: Labor rates differ significantly by region and proximity to urban centers.
  • Contractor Experience: Established, reputable companies may charge more but offer greater reliability and workmanship warranties.
  • Project Complexity: Walls requiring engineering, extensive excavation, or specialized materials demand higher skill levels and thus higher labor costs.

Design Complexity

Simple, straight walls are the most cost-effective. Adding features increases material and labor costs:

• Curves and Corners: Require more cutting of materials (blocks, timber) and more intricate layout work.
• Tiers: Creating multiple levels involves more excavation, more footing construction, and more material overall.
• Integrated Features: Adding stairs, built-in seating, or lighting fixtures complicates the build and adds cost.

Essential Add-ons: Drainage Systems

Proper drainage is critical for the longevity and stability of any retaining wall. It prevents hydrostatic pressure (water buildup behind the wall) which is a primary cause of wall failure. This is not an optional expense. Components include:

• Gravel Backfill (Aggregate): Clean, free-draining gravel (often 3/4″ angular stone) placed directly behind the wall.
• Geotextile Filter Fabric: Separates the gravel backfill from the native soil, preventing clogging of the drainage system.
• Perforated Drain Pipe: Placed at the base of the wall in the gravel zone to collect water and direct it away.
• Weep Holes or Outlet: Allow collected water to exit from the base of the wall or through pipes leading to a safe discharge area.

The cost of these materials and the labor to install them properly must be factored in.

Essential Add-ons: Backfill Material

Behind the drainage aggregate, suitable backfill soil is needed. If the excavated soil is unsuitable (e.g., heavy clay), purchasing appropriate fill material (compactable soil or sand) adds to the cost.

Essential Add-ons: Reinforcement (Geogrid)

Taller retaining walls (typically over 3-4 feet, depending on material and soil conditions) often require soil reinforcement. Geogrid is a strong, polymer mesh laid horizontally within the backfill at specific intervals, extending back into the slope. It interlocks with the soil, creating a stronger, unified mass that resists pressure more effectively. The cost includes the geogrid material and the additional labor for its placement and proper compaction of backfill layers.

Permits and Engineering Fees

• Permits: Most municipalities require building permits for retaining walls exceeding a certain height (often 3 or 4 feet, but check local regulations). Permit fees can range from $100 to over $1,000 depending on the project scale and location.
• Engineering: Walls exceeding specific height limits, supporting critical loads (like driveways), or built in challenging conditions often require plans stamped by a licensed professional engineer. Engineering fees can add several hundred to several thousand dollars to the project cost.

Finishing Touches

Aesthetic additions impact the final cost:

• Wall Caps: Concrete or stone caps provide a finished look to the top of the wall but add material and labor cost.
• Veneers: Applying a stone or brick veneer over a structural concrete or CMU wall adds significant material and skilled labor cost.

Planning Your Retaining Wall Project

Beyond the direct costs, successful retaining wall projects require careful planning.

Drainage is Non-Negotiable

Reiterating this point because it’s vital: inadequate drainage will lead to wall failure. Ensure your plan includes a robust system with gravel backfill, filter fabric, and a functional outlet (pipe or weep holes) to relieve hydrostatic pressure. Do not cut corners here.

Check Local Regulations and Permits

Before starting any work, contact your local building department. Understand the requirements regarding:

• Permit Threshold: The maximum height allowed without a permit (often 3-4 feet, but varies).
• Setbacks: Required distances from property lines.
• Engineering Requirements: Conditions under which stamped engineering plans are mandatory.
• Inspection Schedule: Required points during construction for city inspections.

Long-Term Maintenance

Consider the maintenance needs of your chosen material:

• Timber: Requires periodic sealing or staining; eventual replacement needed.
• Concrete/Block/Stone: Very low maintenance; occasional cleaning may be desired. Check for settling or cracking over time.
• Drainage System: Ensure outlets remain clear of debris.