Constructing Grass-Covered Terrace Steps

A follow-up to the flared sod steps question: The homeowner clarifies they want a grass-surfaced staircase (not concrete) on a 30-inch drop over 21-foot run, likely requiring 6 steps. They need specific dimensions, materials, and execution guidance for a cut-and-fill terrace system.

Terrace Construction Method

The cut-and-fill approach: Excavate the first terrace level, use that soil to build the next terrace, and repeat. This balances earthwork and creates stable, level platforms.

Step Dimension Calculation

• Total rise: 30 inches
• Desired steps: 6
• Riser height: 5 inches each (comfortable for grass steps)
• Tread depth: ~11-12 inches (21 ft run / 6 steps ≈ 42 inches per tread section, but flared design varies)

Materials and Execution

1. Layout: Stake string lines for each terrace level
2. Excavation: Cut into slope for first terrace, stockpile soil
3. Compaction: Firmly compact each terrace base
4. Edging: Install landscape timbers, stone, or concrete curbing to contain soil
5. Backfill: Use cut soil, compact in lifts
6. Topsoil: Apply 4-6 inches quality topsoil on each tread
7. Grass establishment: Seed or sod in fall/early winter; irrigate consistently

Critical Details

Ensure each terrace drains slightly forward (1-2% slope) to prevent water pooling. The boxwood hedges mentioned previously should be planted along the outer edges after terrace completion. For 6 steps on this slope, the flare from 6' to 10' width means each step increases ~8 inches in width.