A French drain around a foundation typically costs $4,000-$12,000 for a professionally installed exterior system, with an average near $7,500. The final price depends on drain length and depth, soil and access, surface restoration, and local labor rates; interior systems and difficult excavations can cost more.
| Item | Low | Average | High | Notes |
|---|---|---|---|---|
| Exterior foundation drain | $2,500 | $7,500 | $18,000 | About 100-250 linear ft; $25-$75 per linear ft |
| Interior perimeter drain | $4,000 | $8,500 | $20,000 | About 100-200 linear ft; includes slab cutting and restoration |
| Sump pump and discharge | $800 | $1,800 | $4,000 | May be additional to drain installation |
What an exterior foundation drain costs by length
Exterior French drains commonly run $25-$75 per linear foot, including trenching, perforated pipe, gravel, filter fabric, and backfill. A straightforward 100-foot installation may total $2,500-$7,500; a 200-foot perimeter can reach $5,000-$15,000 before substantial landscaping or hardscape repairs.
A typical 150-foot exterior project costs about $3,750-$11,250, with roughly $7,500 a useful planning average. Those figures assume normal soil, accessible foundation edges, standard drainage pipe, and a discharge point on the property. High-cost metro areas, deep trenches, and clay or rocky soil can push quotes above the range.
Assumptions: U.S. midrange labor, standard perforated pipe and gravel, normal equipment access, and no major foundation repair.
How trenching, pipe, and gravel shape the quote
Contractors typically price the excavation and drainage assembly together, but an itemized quote helps show where money goes. The following ranges are approximate per linear foot for an accessible exterior installation; a provider may bundle materials, labor, and equipment differently.
| Quote item | Low | Average | High | What it covers |
|---|---|---|---|---|
| Trenching and labor | $12/ft | $25/ft | $45/ft | Excavation, pipe placement, and backfill |
| Pipe, gravel, and fabric | $5/ft | $12/ft | $22/ft | Perforated pipe, washed stone, filter fabric |
| Equipment and access | $3/ft | $8/ft | $18/ft | Machine use, hand digging, and site protection |
| Discharge and restoration | $3/ft | $10/ft | $25/ft | Outlet routing and basic surface repair |
For a 150-foot run, the combined quote commonly falls around $3,750-$11,250 before major restoration or a sump system. Labor may be estimated as crew hours multiplied by an hourly rate, although most contractors provide a fixed project bid.
Why trench depth and soil change the per-foot price
Depth is a major cost driver because deeper excavation takes longer, requires more spoil removal, and can involve added safety measures. A trench around 18-24 inches deep is often less expensive than one 4 feet deep or deeper; actual depth depends on drainage design, foundation conditions, and local requirements.
Soil and obstacles also matter. Rocky ground, dense clay, buried utilities, mature tree roots, and narrow side yards can add roughly 15%-50% or more to a straightforward bid. Runs longer than 200 linear feet may raise the total while sometimes lowering the average per-foot price through more efficient equipment use.
Ask whether the quote specifies trench depth, pipe diameter, gravel coverage, and the route to the discharge point. A low per-foot rate may omit a sump basin, outlet piping, or restoration that another estimate includes.
How many crew hours does a 150-foot drain take
A typical accessible 100-150-foot exterior drain may take a three-person crew about 2-4 workdays, depending on excavation conditions and restoration. Difficult hand digging or a deeper trench can extend the schedule. Labor rates vary, but drainage and excavation trades often bill at an effective $50-$100 per worker-hour before equipment and materials.
Compare the proposed crew size and workdays, not just the hourly rate. A fixed-price proposal should still explain whether equipment, soil hauling, cleanup, and unexpected utility conflicts are included.
Regional labor rates shift foundation drain budgets
Prices in high-cost coastal metros and dense urban neighborhoods can run about 15%-35% above a typical U.S. quote due to wages, access limits, and disposal charges. Rural markets may come in 10%-20% lower when contractors and equipment are nearby, although long travel distances can offset savings.
Local conditions can outweigh broad regional averages. Freeze depth, rainfall patterns, soil type, and local drainage rules may affect the design and excavation depth. Use nearby estimates for the same length and scope when judging whether a bid is high or low.
Which discharge and restoration charges may be extra
Connecting the drain to a sump pump, daylight outlet, or approved stormwater point can add $500-$3,000, depending on distance and equipment. A new sump pump and basin commonly add $800-$2,500; a backup pump or battery system can add several hundred dollars more.
Removing concrete or paving may add $5-$15 per square foot for cutting and basic replacement, while landscaping restoration can range from a few hundred dollars to several thousand. Soil hauling, permits, utility locating, and waterproofing are also worth checking. Confirm the outlet location and restoration limits in writing before work begins.
Three foundation drain quotes at different project sizes
| Example | Scope | Labor and equipment | Estimated total |
|---|---|---|---|
| Small side-yard run | 80 ft exterior, standard soil, $30-$55/ft | 2 workers, 16-24 hours | $2,400-$4,400 |
| Typical perimeter | 150 ft exterior, moderate access, $35-$70/ft | 3 workers, 48-72 hours | $5,250-$10,500 |
| Deep, difficult perimeter | 220 ft exterior, rocky soil, outlet work, $60-$100/ft | 3-4 workers, 5-8 days | $13,200-$22,000 |
These examples show how access, soil, and discharge work alter totals even when the basic system is similar. They exclude extensive landscaping replacement and major foundation repairs.
How to lower the drain price without cutting performance
Keep the scope focused on the wet area if a drainage professional confirms that a full perimeter is unnecessary. Clearing access, moving planters, and identifying irrigation lines before the crew arrives can reduce hand labor and delays. Compare at least three written bids using the same length, depth, pipe, gravel, outlet, and restoration specifications.
Choose standard drainage materials that meet the design rather than paying extra for upgrades without a clear purpose. If water entry is limited to a downspout or surface grading problem, correcting that source may cost less than a foundation drain. Do not reduce trench depth, gravel coverage, or outlet capacity simply to accept the lowest bid.