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9.4 Filling a gabion basket

How to fill a basket so it stays square: in thirds, with bracing wires, face stones placed by hand and a little extra on top.

Front view of a 1 m tall gabion being filled: stones in three layers, with bracing wires across the basket after the first and second third, face stones placed by hand and a small overfill at the top. 1 Overfill 25–50 mm, for settling 2 Second bracing at ⅔ of the height 3 First bracing at ⅓ of the height 4 Lifts at most 300 mm at a time
A 1 m gabion filled in thirds.

At a glance

Difficulty
2 of 4
Time
A few hours per m³ by hand
Tools
Work gloves, safety glasses, pliers or lacing tool, spiral binders or rings, board and clamps to hold the face flat, bucket or barrow
Parts
  1. 1  Face stones
  2. 2  Bracing wires
  3. 3  Core stones
  4. 4  Lid

What you need per m³ of basket

MaterialSizeTypeAmount
Fill stone 100–200 mm Hard, clean, bigger than the mesh (9.2) 1.7–1.8 t
Bracing wires – Galvanized, or the basket maker's stiffeners 4 per exposed face
Binders or lacing wire – To join panels and baskets –

Why fill in thirds and brace?

⅓ · ⅔

Stone pushes the mesh outwards. Wires across the basket at a third and two thirds of the height hold the faces flat. Baskets up to about 450 mm tall do not need them; 500 mm baskets get one set at half height.

+25–50 mm

The stones settle into each other over the first months. Overfilling 25–50 mm above the rim lets the lid sit tight on the stone afterwards instead of rattling over a gap.

Step by step

  1. 1

    Set out and join the empty baskets.

    Stand the baskets on the finished base (9.3), stagger the vertical joints between rows like brickwork, and join each basket to its neighbors along every edge before any stone goes in. Clamp a board to the face to keep it flat while you fill.

    Empty baskets joined on the base
  2. 2

    Fill the first third, face first.

    Place the face stones by hand, flat side out, then fill the middle. Fill at most 300 mm at a time, and never let one cell get more than 300 mm higher than the next. Do not drop stone from higher than about 1 m.

    The first layer with face stones placed
  3. 3

    Fit the first bracing wires.

    Hook wires from the front face to the back, about 300–330 mm apart, two per face of each cell. In end baskets, brace both ways. Welded baskets can take stiffeners across the corners, 300 mm in from each corner.

    Bracing wire hooked front to back
  4. 4

    Fill to two thirds, brace again, then fill to the top.

    Repeat: face stones first, then the core, then the second set of wires. Small and odd stones go in the middle, never on the face. Fix any bulge now; afterwards it cannot be pushed back.

    The basket two thirds full
  5. 5

    Overfill 25–50 mm and close the lid.

    Level the top layer so the lid lies flat on the stone, pull the lid down to the edges and join it all round. Do not lever it shut with a crowbar; it bends the mesh. Stack the next row only after the row below is closed, and join the two.

    Lid closed over the overfilled stone
Specifications
Basket heightLayersBracingOverfill
up to 450 mm1–2not needed25–50 mm
500 mm2 × 250 mmafter the first layer25–50 mm
1 m3 × about 330 mmat ⅓ and ⅔25–50 mm

Lifts

At most 300 mm at a time; no cell more than 300 mm higher than its neighbor (UFGS, NRCS, Iowa DOT, Hertfordshire). Drop height at most 0.9–1.2 m (UFGS, Anne Arundel County).

Bracing

Two connecting wires on each exposed face of each cell between lifts, about 300 mm apart; not needed up to 450 mm (Iowa DOT). Braces at about 330 mm centers (Wyndham, Cessnock). End units braced in two directions (Hertfordshire). Welded baskets: diagonal stiffeners 300 mm from the corners (NRCS).

Face

Visible faces placed by hand for a neat, dense face (UFGS, Iowa DOT, NRCS, Cessnock). Refill where bulges or dips exceed 50 mm (Wyndham, Cessnock).

Joining

Join corners to neighboring baskets before filling; join each row to the one below after it is closed (UFGS). Lacing in alternate single and double loops at most 100–150 mm apart, or rings at most 150 mm apart (UFGS).

Sources

  1. US Department of Defense, UFGS 31 36 00 Gabions: rock 100–200 mm for gabions 500 mm and taller, large enough not to pass the mesh; at most 5 % oversize or undersize, undersize only inside, never on the face; room for three or more layers of rock per compartment; hard, angular to round, durable rock that does not break down in water or weather, with freeze-thaw testing; at most 5 % dirt, sand, clay and fines; 300 mm lifts, no cell more than 300 mm higher than its neighbour; stiffeners at ⅓ and ⅔ of the height; hand-placed visible faces; drop height at most 0.9–1.2 m; overfill 25–50 mm; no foundation work on frozen ground
  2. USDA NRCS Construction Specification 464, Wire mesh gabions and mattresses: baskets 300–900 mm thick: rock 100–200 mm, at least 85 % in that range; welded mesh 75 × 75 mm, woven 83 × 114 mm; no cell more than 300 mm deeper than its neighbour; two crossties per 300 mm of depth in cells over 450 mm tall; welded baskets braced across the corners 300 mm from each corner; outer stones placed by hand; last layer level with the top edges; no crowbars to close lids; foundation free of mounds and dips
  3. Iowa DOT Standard Specifications §9050, Gabions and revet mattresses: lifts of at most 300 mm; stones turned by hand after each lift; connecting wires not needed in gabions up to 450 mm tall; two wires on each exposed face of each cell between lifts, about 300 mm apart; overfill 25–50 mm; firm, unyielding subgrade compacted to 95 % of standard Proctor
  4. Hertfordshire County Council, standard drawing HST-0600-001 Typical gabion retaining walls: fill graded 100–200 mm; welded mesh 75 × 75 mm; retained height 350–550 mm with one 1.0 × 1.0 m gabion, up to 1.5 m with a 1.5 m wide gabion under a 1.0 m one; gabions buried 300–500 mm; face batter 6°; foundation of compacted well-graded granular fill or concrete, at least 50 mm wider than the basket on each side; bracing wires after ⅓ and ⅔ of the height, end units braced both ways; no compartment more than 300 mm higher than its neighbour; exposed faces hand packed; vertical joints staggered; slight overfill where gabions are stacked; geotextile behind the gabions and on all buried faces
  5. Wyndham City Council (Victoria), Technical Specification 715 Gabions and rock mattresses: gabion rock 100–250 mm with at least two broken faces, free of laminations and cracks; welded mesh at most 75 × 75 mm; braces at about 330 mm after filling ⅓ and ⅔; refill where bulges exceed 50 mm; perforated drain pipe at least 100 mm at the base of the rear of a gabion retaining wall
  6. Cessnock City Council (NSW), AUS-SPEC 0294 Gabion walls and rock filled mattresses: rock sized for at least three layers in a gabion; 1 m gabions filled in three layers with bracing after the first and second; 500 mm gabions in two layers of 250 mm; bracing wires at 330 mm; exposed faces placed by hand; overfill 25–50 mm; prepared foundation sloping at most 1 in 10; geotextile between gabions and retained soil; heavy plant kept 1 m from the units
  7. Anne Arundel County (Maryland), Section 02294 Gabions: stone by basket thickness: 150 mm baskets 75–150 mm, 230–450 mm baskets 100–175 mm, 900 mm baskets 100–300 mm; mesh opening at most 100 mm; hard, angular, weather-resistant stone; at least two courses; drop height at most 0.9 m; subgrade smooth and firm
  8. FHWA Federal Lands, standard drawing E253-01 Gabion retaining wall: rock-filled gabions weigh 110 lb/ft³ (about 1.75 t/m³); front face battered 1:12; underdrain at the back with outlets
  9. FHWA Federal Lands, standard drawing W253-3: filled gabions weigh 105 lb/ft³ (17.6 kN/m³, about 1.7 t/m³)

Amounts: a filled gabion weighs 105–110 lb/ft³ in the FHWA drawings, about 1.7–1.8 t/m³. Bracing count from Iowa DOT: a 3 ft (0.9 m) cell with one exposed face takes four connecting wires, an end cell with two exposed faces eight.

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