How to install coir netting on a slope

Coir netting only works if it stays in tight contact with the soil. Most failures come from the edges: water gets under a loose top edge or an open overlap and carries soil away beneath the mesh. These steps follow published guidance from a Tamil Nadu Agricultural University handbook and California’s transport department.

Step by step

1. Prepare the surface. Grade the slope smooth and remove rocks, roots and debris. Caltrans warns that rocks and debris can lift the netting and let erosion start underneath.
2. Seed at the right time. With 400 and 700 GSM netting, seed can go down before or after the netting. With 900 GSM, seed first: Caltrans notes it is too dense to seed through effectively afterwards.
3. Dig anchor trenches. Cut trenches about 30 cm deep and 15 cm wide along the top and the ends of the area, kept free of mud and slurry.
4. Anchor the top edge. Lay the start of the roll in the top trench, pin it, then backfill and compact.
5. Roll down the slope. Unroll in the direction the water flows, not across the slope. Lay it loosely so it follows the ground rather than bridging hollows.
6. Overlap correctly. Overlap neighbouring rolls by about 15 cm side to side and 20 cm end to end, with the upper roll on top so water runs over the joint, not into it.
7. Pin it down. Use U-shaped pins about 15 cm long or J-shaped hooks about 22 cm long, made from 3 mm steel wire. Wooden or bamboo pegs also work. Space them about 50–75 cm apart across the area, closing up to 30–50 cm along overlaps.
8. Finish the edges. Bury the ends and sides in their trenches, pin, backfill and compact.

Where it is suited

Caltrans recommends coir netting on cut and fill slopes between 2:1 and 1:1 (horizontal to vertical), with 400 GSM limited to slopes of 3:1 or gentler. In streams and channels, design should be checked by the project engineer, because flowing water puts different loads on the netting.

After installation

Inspect after the first heavy rain. Re-pin any lifted edges, fill any rills that have formed under the mesh and reseed bare patches early. Small repairs in the first weeks prevent large ones later.

Not sure which grade to lay? See our grade guide or ask us.