Calculator
French drain cost calculator
Costs split sharply by placement. A yard drain and an exterior foundation drain are the same trench at different depths, and the depth is most of the price.
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National ranges for 2026, before regional adjustment. Metro labour rates swing this ±30%. Use it to judge whether a quote is reasonable, not as a substitute for one.
Get quotes from drainage contractors in your area
Three local contractors, no cost to you. Useful mainly as a sanity check against the number above — quotes on the same job routinely vary by 40%.
What actually moves the price
Depth, first and last
A yard drain at 20 inches and a footing drain at seven feet are the same pipe in the same gravel. The second costs three to five times more per foot because of excavation volume, spoil handling, shoring, and the fact that a machine has to reach a wall it cannot stand on top of.
Restoration is the invisible half
Trenching under a lawn costs a few dollars a foot to put right. Trenching under a paver patio, a concrete walkway, or a driveway means demolition and replacement, and that line alone can rival the drain. When comparing quotes, check whether restoration is included or excluded — this is the most common reason two bids on identical work land thousands apart.
The outlet
Daylight is free. A dry well is $1,500–$4,000. A sump system is $1,000–$3,000 installed, plus a battery backup you should not skip, plus the electrician if there is no circuit nearby.
Interior versus exterior
Interior basement systems run roughly half the cost of exterior excavation and can be done in winter without destroying the landscaping. They also do not stop water reaching the wall — they collect it after it arrives. If the wall itself is failing, interior work manages a symptom that keeps getting worse. More on that decision.
Check the cheap fix first. A meaningful share of "I need a French drain" jobs are downspouts discharging beside the foundation. An extension costs $40. Confirm that is not your problem before spending four figures, and start with where the roof water goes.