Retaining Wall Calculator

Calculating materials for a retaining wall is essential for budgeting and planning your landscaping or construction project. Our retaining wall calculator helps you:

• Determine the volume of material needed based on wall dimensions
• Calculate the number of blocks, bricks, or stones required
• Estimate the total cost of materials
• Plan for different wall types and materials

The calculator offers two main calculation types:

1. Block/Brick Wall: For walls built with discrete units like concrete blocks, bricks, or stones.
2. Poured Concrete: For monolithic walls made from poured concrete.

To use the calculator, select the wall material, measurement unit, and enter the dimensions (height, length, and thickness). You can also specify the cost per unit to get an accurate cost estimate.

Retaining walls come in various types, each suited for different applications and soil conditions:

Gravity Walls

Gravity walls rely on their mass to resist pressure from behind. They're typically made of heavy materials like concrete blocks, natural stone, or gabion baskets.

• Pros: Simple design, minimal reinforcement needed for low walls
• Cons: Requires substantial thickness for taller walls
• Best for: Low to medium height walls (up to 3-4 feet)

Cantilever Walls

Cantilever walls are L-shaped reinforced concrete structures that use leverage to convert soil weight into wall stability.

• Pros: More efficient use of materials for taller walls
• Cons: Requires professional design and construction
• Best for: Medium to tall walls (4-20 feet)

Segmental Retaining Walls

Segmental walls use interlocking concrete blocks that don't require mortar, making them popular for DIY projects.

• Pros: Easy installation, flexible design, good drainage
• Cons: May require geogrid reinforcement for taller walls
• Best for: Residential landscaping, terraced gardens

Gabion Walls

Gabion walls consist of wire mesh baskets filled with stone, providing excellent drainage and a natural appearance.

• Pros: Excellent drainage, flexible, can use local stone
• Cons: Labor-intensive to fill baskets properly
• Best for: Areas with water issues, natural-looking landscapes

Timber Walls

Timber walls use pressure-treated wood or railroad ties to create a natural-looking retaining structure.

• Pros: Relatively inexpensive, easy to work with
• Cons: Shorter lifespan (15-20 years), susceptible to rot
• Best for: Low walls, rustic settings, temporary solutions

When selecting a material, consider the wall height, soil conditions, aesthetic preferences, budget, and your DIY skill level. For walls over 4 feet (1.2 meters) high, professional design and installation are recommended regardless of material.

Proper design is crucial for a safe and long-lasting retaining wall. Consider these important factors:

Height and Thickness

• Wall height determines the required thickness and reinforcement
• Base thickness typically 1/3 to 1/2 of the wall height
• Walls over 4 feet (1.2 meters) usually require engineering design
• Consider stepped or terraced designs for very tall slopes

Drainage

• Proper drainage is essential to prevent water pressure buildup
• Include gravel backfill (at least 12 inches/30 cm wide)
• Install perforated drain pipe at the base of the wall
• Incorporate weep holes every 6-8 feet (1.8-2.4 meters)
• Ensure proper grading to direct surface water away from the wall

Foundation

• Excavate below frost line to prevent frost heave
• Create a level base of compacted gravel (4-6 inches/10-15 cm thick)
• Ensure the foundation is wider than the wall (typically 1.5-2 times the wall thickness)
• Compact soil properly to prevent settling

Reinforcement

• Taller walls require reinforcement (steel rebar, geogrid, etc.)
• Cantilever walls need proper steel reinforcement design
• Segmental block walls over 3 feet (0.9 meters) typically need geogrid reinforcement
• Reinforcement requirements increase with wall height and soil pressure

Soil Conditions

• Understand your soil type (clay, sand, loam, etc.)
• Clay soils retain more water and exert more pressure
• Sandy soils provide better drainage but may require more reinforcement
• Consider soil testing for large projects

The total cost of a retaining wall depends on several factors:

• Material costs: Varies widely from $10-15 per square foot for timber to $20-50 for stone
• Wall dimensions: Height, length, and thickness directly impact material quantities
• Site preparation: Excavation, grading, and foundation work
• Drainage systems: Gravel, drain pipe, filter fabric
• Reinforcement: Rebar, geogrid, or other structural supports
• Labor costs: Professional installation can double the material costs
• Accessibility: Difficult access may increase costs
• Permits and engineering: Required for taller walls
• Finishing touches: Caps, veneer, plantings, lighting

For budgeting purposes, expect to pay:

• DIY small wall (under 3 feet): $15-30 per square foot of wall face
• Professional installation: $30-60 per square foot of wall face
• Engineered walls (over 4 feet): $50-150 per square foot of wall face

Remember to factor in long-term maintenance costs when comparing materials. While timber may be less expensive initially, it will likely need replacement within 15-20 years, whereas concrete or stone walls can last 50+ years with minimal maintenance.

• Check local regulations: Obtain necessary permits before starting
• Call before you dig: Contact utility companies to mark underground lines
• Plan for drainage: This is the most critical aspect of retaining wall success
• Prepare a proper base: Take time to create a level, compacted foundation
• Backfill properly: Use gravel for the first 12 inches behind the wall
• Compact in layers: Add and compact backfill in 6-8 inch layers
• Include a slight tilt: Build the wall with a slight backward lean (about 1 inch per foot of height)
• Consider freeze-thaw cycles: In cold climates, ensure the foundation is below the frost line
• Use geotextile fabric: Place between soil and gravel to prevent soil migration
• Install proper caps: Use wall caps to improve appearance and prevent water infiltration
• Plan for the long term: Consider how plants, erosion, and settling might affect your wall
• Know your limits: Hire professionals for complex or tall walls