French Drain Gravel - Material Guide
Picking the right gravel for a french drain gravel project? This guide covers the materials that fit best, how much you need, and what it costs delivered.
Most french drain gravel projects fail in the prep stage, not the gravel itself. Soft subgrade, missing fabric, or stone with the wrong gradation all show up six months later as ruts, weeds, or settling. The guide below walks the install in the order a pro crew would tackle it, with the numbers we use to spec material on bids in this region.
Best materials for french drain gravel
What french drain gravel needs in a material
- Size and shape: 3/4 to 1.5 inch clean, washed stone.
- Drainage: maximum void space around perforated pipe.
- Compaction: never compacted, voids carry the water.
The three specs above drive every other choice on a french drain gravel job. Order the wrong size and the surface fails fast. Pick a material that drains the wrong way and you fight standing water or washouts. Get these right and the install steps below take care of the rest.
How to install french drain gravel
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1
Excavate trench
Dig 18 inches deep and 12 inches wide with a 1 percent slope to daylight.
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2
Line with fabric
Roll non-woven geotextile into the trench with extra fabric on each side.
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3
Bed the pipe
Lay 4 inches of clean stone, set perforated pipe holes-down, cover with stone.
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4
Wrap and finish
Fold fabric over the top, cover with topsoil or decorative stone.
How much french drain gravel material do you need
| Project size | 3 inch depth | 4 inch depth |
|---|---|---|
| 100 sq ft | 0.9 cu yd / 1.3 tons | 1.2 cu yd / 1.7 tons |
| 300 sq ft | 2.8 cu yd / 3.9 tons | 3.7 cu yd / 5.2 tons |
| 600 sq ft | 5.6 cu yd / 7.8 tons | 7.4 cu yd / 10.4 tons |
Quantities above assume crushed stone at roughly 1.4 tons per cubic yard. Pea gravel and river rock run a bit lighter, decomposed granite a bit denser. Add 10 percent waste for irregular shapes and edge losses.
What french drain gravel costs in 2026
| Region | Delivered per ton | Typical 300 sq ft project |
|---|---|---|
| Northeast | $46 to $79 | $161 to $277 |
| Midwest | $35 to $62 | $123 to $217 |
| South | $33 to $59 | $116 to $207 |
| West | $53 to $97 | $186 to $340 |
The bands below are 2026 delivered prices for full truck loads from a local quarry. Pricing climbs in metros with longer haul distance, drops in markets with quarry competition. Color washes, screenings, and specialty grades sit at the top end of the range.
French Drain Gravel mistakes to avoid
- Stone with fines, which clogs the drain inside one rain season.
- Trench laid flat, with no fall to an outlet.
- No fabric wrap, so silt fills the voids fast.
- Outlet covered by sod, so the system has nowhere to push the water.