Construction
French Drain Calculator
Drain length, trench width and depth give gravel, pipe, and fabric quantities.
Gravel (cu yd)
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- Pipe (ft)
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- Fabric (sq ft)
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- Trench volume (cu ft)
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FAQ
Pipe holes up or down? +
Holes face down. Water enters from the gravel-filled trench, into the pipe, and flows downhill.
Slope? +
At least 1 percent (1 inch per 8 feet). More is fine.