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Gabion wall: how many baskets and how much stone?

Calculate the volume of a gabion wall, the number of baskets and the tons of stone to fill them, taking the voids between stones into account.

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Results

Number of baskets

5

Assumes the wall dimensions are multiples of the basket size

Wall volume

10.00

Stone to order

15.5

Stone weight per unit of wall volume
1.76 t/m³
Wall face area
90.0 ft²

What a gabion is

A gabion is a wire mesh basket filled with stone. Stacked together, gabions form retaining walls, garden walls, erosion barriers along rivers, noise barriers and decorative features. They are heavy enough to hold back soil by their own weight, and water drains freely through the stones, so they do not need weep holes.

How the calculator works

  1. Wall volume = length × height × thickness.
  2. Number of baskets = wall volume ÷ basket volume, rounded up. This assumes the wall dimensions are whole multiples of the basket size; adjust the wall size or use smaller baskets for the ends.
  3. Stone weight = wall volume × stone density × (1 − voids) × (1 + waste).

Stones packed in a basket leave gaps between them. With hand-placed stone of 4 to 8 inches, the voids are usually 30 to 40% of the volume. Typical solid densities are 2.7 t/m³ for granite or basalt, 2.5 for limestone, 2.3 for sandstone and about 2.2 for recycled concrete.

Example

A garden retaining wall 30 feet long, 3 feet high and 3 feet thick, built with 6 × 3 × 3 ft baskets filled with granite:

  • Wall volume: 270 cubic feet = 10 cubic yards
  • Baskets: 270 ÷ 54 = 5
  • Stone: 7.65 m³ × 2.7 × 0.65 × 1.05 ≈ 15.5 tons (about 14.1 metric tons)

Choosing the stone

  • Use hard, durable stone that will not crack in freezing weather.
  • The stone must be larger than the mesh openings. For a 3-inch mesh, use stone of about 4 to 8 inches.
  • Place the best-looking stones by hand against the visible face, and fill the core with cheaper stone.
  • Install internal bracing wires every 12 inches or so of height to stop the faces bulging.

Building a retaining wall

Gabion retaining walls usually need a base at least half as deep as the wall is high, and the courses are stepped back toward the soil, typically by 6 inches per course. Lay them on a compacted gravel base, with geotextile fabric between the soil and the baskets to stop fines washing in.

In many places, a retaining wall taller than about 4 feet needs a permit and a design by an engineer, especially if it holds back a slope, a driveway or a building. Check your local building code before you start.

Frequently asked questions

What is a gabion?

A wire mesh basket filled with stones, used for retaining walls, erosion control, garden walls and decorative features. The flexible, permeable structure lets water drain through and tolerates some ground movement better than a rigid wall.

How much stone does a gabion need?

Stone fills about 60 to 70% of the basket; the rest is voids. With granite at a density of 2.7, a cubic yard of basket takes about 1.3 metric tons (1.5 US tons) of stone. Order 5 to 10% extra for settling and hand-placing the face.

What size stone should I use?

Stones should be larger than the mesh openings, usually 4 to 8 inches (100 to 200 mm) for standard 3-inch mesh. Hard, durable, frost-resistant stone such as granite, basalt or dense limestone lasts longest.

Do gabion walls need a permit?

Garden walls usually do not, but retaining walls above about 4 feet, or those supporting a slope, driveway or building, often need engineering and a permit. Gabion retaining walls are usually built with a base about half the height and stepped back toward the soil.

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Results are estimates provided for information purposes. They do not replace professional advice.

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