How Much Gravel for a 50 Foot French Drain?
How much gravel for a 50 foot French drain: about 2.62 cubic yards, or roughly 3.7 tons, for a trench 12 inches wide and 18 inches deep with a 4-inch perforated pipe.
Volume and tonnage calculator →Gravel by trench size over 50 feet
| Trench (W × D) | Cubic yards | Tons |
|---|---|---|
| 6 × 12 in | 0.76 | 1.1 |
| 12 × 18 in | 2.62 | 3.7 |
| 12 × 24 in | 3.54 | 5.0 |
| 18 × 24 in | 5.39 | 7.6 |
Figures subtract a 4-inch pipe and assume about 1.4 tons per yard of washed stone.
Related: How Much Gravel for a 100 Foot French Drain?
Best stone for the drain
Washed angular stone around 3/4 inch is the usual pick. Avoid crusher run or anything with dust; the point is open space for water to move. See the best gravel for a French drain.
Wrap and slope
Line the trench with non-woven filter fabric, add a couple of inches of stone, lay the perforated pipe holes down, cover with stone and fold the fabric over the top. Slope the trench about 1 percent (1 inch per 8 to 10 feet), which over 50 feet is roughly 5.6 inches of fall. Call 811 before digging.
Related: How Much Gravel for a 10 Foot French Drain?
Measuring the run
Lay out the route with paint, measure its length and note the start and end elevations. A line level or a laser level confirms you have enough fall. Plan the trench width around your shovel or trencher size.
Cost and tools
Gravel is the bulk of the material cost, followed by pipe and fabric. Renting a trencher saves a lot of digging on long runs. A wheelbarrow, a flat shovel and a level finish the toolkit.
Common mistakes
Using gravel with fines, skipping the fabric and laying the pipe with no consistent slope are the usual causes of failure. A drain with no proper outlet simply fills and holds water. Another mistake is digging without calling 811 to locate buried lines.
Questions people ask
How many tons of gravel for a 50 ft French drain?
About 3.7 tons for a 12x18 inch trench.
How many yards of gravel for a 50 ft French drain?
About 2.62 cubic yards.
What size gravel for a French drain?
Clean washed stone around 3/4 inch, such as #57.
How much slope does a French drain need?
About 1 inch of fall per 8 to 10 feet.
Do I need fabric for a French drain?
Yes, non-woven filter fabric keeps soil out of the stone.
Related guides
- Best Gravel for a French Drain: Size and Type
- French Drain Along an Asphalt Driveway
- How Much Gravel for a 30 Foot French Drain?
- How Much Gravel for a 40 Foot French Drain?
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