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Tons of rip rap for a shoreline, ditch, or culvert outlet, by rock class and blanket thickness.
With these inputs:
| Result | Value |
|---|---|
| Rip rap | 46.67 tons |
| Blanket thickness | 18 in |
| Truck loads (20 t) | 3 |
| Estimated cost | $2,100 – $3,967 |
| Area | 600 sq ft |
| Median rock size (D50) | 9 in |
| Thickness (2 × D50, min 12") | 18 in |
| Volume | 33.33 yd³ |
| Weight (1.4 t/yd³ placed) | 46.67 tons |
| Non-woven filter fabric | 720 sq ft |
Key the toe of the rip rap into a trench at least one blanket-thickness deep, and lay non-woven geotextile or a gravel filter layer underneath so soil is not washed out between the stones. Work in a regulated waterway usually needs a permit.
Rip rap is laid as a blanket at least one and a half to two times as thick as the median rock size. Pick the rip rap class and the slope dimensions, and this calculator sets the blanket thickness, then returns the volume, tonnage, truck loads, and the filter fabric that must go underneath.
At least 1.5 to 2 times the median stone size (D50), and never less than 12 inches. Class II rip rap with a 9 inch median is usually placed 18 inches thick.
Placed rip rap weighs about 1.3 to 1.5 tons per cubic yard. The stone itself is heavier, but the large voids between rocks bring the in-place density down.
Rip rap stone costs roughly $45 to $85 per ton delivered, depending on class and haul distance. Placement with an excavator often costs as much again, especially on steep or wet banks.
Yes. Without a filter layer, water moving through the stones pulls the soil out from underneath and the rip rap slumps. Use a heavy non-woven geotextile or a 6 inch bedding layer of smaller stone.
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