1. What is Backfill Calculation?

Backfill calculation determines the amount of material needed to fill the space behind a retaining wall. Proper backfill is crucial for drainage and structural stability of the wall.

2. How Does the Calculator Work?

The calculator uses the backfill formula:

Where:

• \( Length \) — Length of the wall (ft)
• \( Height \) — Height of the wall (ft)
• \( Depth \) — Depth of backfill needed (ft)
• 27 — Conversion factor from cubic feet to cubic yards

Explanation: The equation calculates the volume in cubic feet and converts it to cubic yards (since most backfill materials are sold by the cubic yard).

3. Importance of Backfill Calculation

Details: Accurate backfill calculation ensures you order the right amount of material, avoiding costly overages or delays from under-ordering. It's particularly important for 30x3 retaining walls where proper drainage is critical.

4. Using the Calculator

Tips: Measure the length of your wall in feet, the height of the wall in feet, and the required depth of backfill (typically 12-18 inches for a 30x3 wall). Enter all values as positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Why divide by 27 in the formula?
A: There are 27 cubic feet in 1 cubic yard. The division converts the volume from cubic feet to cubic yards.

Q2: What's the typical backfill depth for a 30x3 wall?
A: For a 30x3 retaining wall, backfill depth is typically 1-1.5 feet (12-18 inches) behind the wall.

Q3: What material should I use for backfill?
A: Clean, free-draining material like gravel or crushed stone is recommended for proper drainage behind the wall.

Q4: Should I include the base material in this calculation?
A: No, this calculation is specifically for the backfill material behind the wall. Base material should be calculated separately.

Q5: How much extra should I order?
A: It's recommended to order 10-15% more than the calculated amount to account for compaction and spillage.