How Much Dirt Do You Need to Build an Earthship?

By Chad Castellanos | January 22, 2025 |

How Much Dirt Do You Need to Build an Earthship?

Building an Earthship requires a significant amount of dirt, as earth-packed tires form the foundation and walls of the structure. Calculating the exact amount depends on the square footage of your Earthship and its unique design. Below is a detailed breakdown of the dirt required, based on common Earthship building practices.

Earthship Dirt Requirements: Overview

Tires: Each tire is packed with dirt to create a solid, dense building block.
- Each tire holds approximately 8 five-gallon buckets or 4 wheelbarrows of dirt.
Walls: Earth-packed tires are stacked to create walls that are approximately 13 tires high on the back and side walls and 3 tires high along the south-facing greenhouse.
Wing Walls: The wing walls taper down, extending about 20 feet on either side of the Earthship.
Buried Earth: The back and side walls are buried in a dirt mound that tapers back approximately 40 feet and rises to about 13 feet at the ceiling level.

Step 1: Determine the Number of Tires

Main Walls

The Earthship’s foundation and walls on three sides are 13 tires high. The south-facing wall is 3 tires high.
Assume a wall length of 75 feet on the back, 25 feet on each side, and 75 feet for the front (greenhouse).
Tire placement: 2.5 tires per linear foot (approximation for standard tire sizes).

Tire Count:

Back Wall: 75 feet × 2.5 tires/foot = 188 tires
Side Walls (x2): 25 feet × 2.5 tires/foot × 2 walls = 125 tires
Front Wall (Greenhouse): 75 feet × 2.5 tires/foot = 188 tires

Wing Walls

Each wing wall tapers down over 20 feet.
Average height: 6 tires (tapering from 13 to ground level).
Tire count: = 100 tires

Total Tire Count: 601 tires

Step 2: Calculate Dirt for Tires

Each tire holds approximately:

8 five-gallon buckets of dirt, or
4 wheelbarrows of dirt.

Dirt Volume for Tires:

Total tires: 601
Dirt per tire: 8 buckets
- Convert buckets to cubic feet:

Step 3: Additional Dirt for Burial

The back and side walls are buried in a mound of dirt:

Dimensions: Tapers from ground level to 13 feet high, extending 40 feet back.
Approximate Volume:
- Use the formula for a tapered prism:
- Base area:
- Height: 40 feet

Total Dirt Required

Dirt for Tires: ~3,221 cubic feet
Dirt for Burial: ~45,500 cubic feet

Grand Total: ~48,721 cubic feet of dirt

Converting to Truckloads

Most dump trucks carry approximately 15 cubic yards of dirt (1 cubic yard = 27 cubic feet).

Conclusion

Building an Earthship is a dirt-intensive endeavor. For a 1,875-square-foot structure, you will need approximately 48,721 cubic feet of dirt, equivalent to about 121 truckloads. By sourcing dirt locally and using on-site excavation, you can significantly reduce costs and environmental impact. With careful planning, your Earthship can rise from the earth to become a self-sufficient and sustainable home.