MAMBA DRAINAGE SERVICES
French Drain Installation Vancouver
Wet basement walls in November? Yard turning to mud every winter? Water pooling against the retaining wall? A properly installed French drain moves the water before it gets to the foundation.
Excavation + perforated pipe + drain rock + filter sock + tie-in. Permits included. (778) 961-0824.
When You Need a French Drain in Vancouver
A French drain is a trench filled with drain rock containing a perforated pipe at the bottom. Surface water and groundwater seeps into the rock voids, flows along the pipe to a tie-in point (storm sewer or daylight outflow), and stays out of your basement, yard, or retaining wall. The function is the same as perimeter drain tile but for surface and slope drainage rather than foundation-perimeter.
Three common Vancouver French drain jobs:
Exterior foundation French drain. Adds capacity to an undersized or aging perimeter drain system. Common in pre-1970 East Van and Burnaby homes where original drainage was undersized for current rainfall loads. Trench follows the foundation line at footing depth, ties to existing sump pit or new daylight outflow. Typical: $14,500-$32,000 (similar scope to drain tile replacement).
Yard slope drainage. Property with significant slope where surface water flows toward the house or accumulates in a low spot. French drain along the slope intercepts the surface water before it gets to the foundation. Typical: $4,989-$12,989 depending on length and depth.
Retaining wall back-drainage. New retaining wall construction requires back-of-wall drainage to prevent hydrostatic pressure that would otherwise blow out the wall. Existing failing retaining walls often need French drain installed behind them as part of the rebuild. $2,989-$7,989 typical for retaining wall back-drainage.
Driveway and patio sub-drainage. Some sites need below-grade French drains to manage groundwater under paved surfaces. Combined with surface trench drains and catch basins for full water management. $4,489-$9,989.
Every installation includes: permits where required (City of Vancouver requires permits for storm sewer tie-ins), excavation, perforated pipe install, drain rock backfill, filter fabric or sock to prevent silt migration, surface restoration. We coordinate with landscape contractors for final finish on properties with high-end landscaping.
Anatomy of a Properly Installed French Drain
Skipping any of these steps is why some French drain installs fail in 5-8 years instead of lasting 30+.
Excavation depth and width. Foundation French drains need to be at footing depth (typically 6-9 feet for Vancouver basements) to intercept water before it gets to the foundation wall. Yard French drains need 24-36″ depth for adequate slope and frost protection. Trench width 18-24″ for working room.
Filter fabric. Lines the trench walls before drain rock goes in. Prevents native soil from migrating into the drain rock void space and silting up the system. We use Mirafi 140N non-woven geotextile or equivalent. Skipping the filter fabric is the #1 reason French drains fail prematurely.
Drain rock. 3/4″ clear angular gravel – not pea gravel, not crushed limestone. Angular shape creates void space for water flow. Crushed limestone has fines that block voids. We use minimum 6″ of drain rock below the pipe and minimum 12″ above the pipe. Typical trench has 18-24″ of drain rock total.
Perforated pipe. 4″ perforated PVC SDR-35 with filter sock (additional silt protection on the pipe itself). Wider applications use 6″ perforated. Some installers use corrugated black HDPE – cheaper but more prone to crushing under settling soil. We use rigid SDR-35 PVC for residential and commercial.
Pipe slope. Minimum 1% slope (1 inch per 8 feet) toward the tie-in point. Drives water flow without standing water in the pipe. Critical for long-term function.
Tie-in. Storm sewer connection via Mission Y-fitting or saddle tap (City permit required), or daylight outflow at least 10 feet from foundation with riprap dispersion. Some properties tie the French drain to an existing sump pit system.
Surface restoration. Topsoil layer above the drain rock with filter fabric separator (prevents topsoil from washing into the drain). Sod or seed restoration. Hardscape (pavers, patio, driveway) restored to original condition.
City of Vancouver permits required for storm sewer tie-ins. We pull the permit, schedule inspection, and produce certificate of work.
Foundation, Yard Slope, and Retaining Wall Applications
Foundation French drain installation is essentially full perimeter drainage installation. Excavate around the entire foundation, install footing-depth French drain tied to sump or daylight, drainage membrane on the foundation wall (Platon, DMX, or equivalent), backfill with drain rock minimum 12″ above the pipe, native soil with filter fabric separator, surface restoration. Total project typical 5-9 working days. $14,500-$32,000 for a typical 1,500-2,500 sq ft Vancouver lot.
If you’re already planning drain tile replacement, the French drain work is the same excavation – we typically quote them together as one project.
Yard slope drainage runs across the slope above the house, intercepting surface water before it reaches the foundation. Trench depth 24-36″ depending on grade. Tie to storm sewer or daylight outflow downslope. Common application in Kerrisdale, West Point Grey, and West Van homes with significant terrain change. $4,989-$12,989.
Retaining wall back-drainage prevents hydrostatic pressure behind the wall. Without it, even a well-built retaining wall can crack or rotate forward after a few wet winters. Install during new wall construction or as part of existing wall rebuild. $2,989-$7,989.
Driveway and patio sub-drainage handles groundwater that would otherwise heave the paved surface during freeze-thaw cycles. Less common in Vancouver’s mild winters than in Calgary or Edmonton, but valuable for properties with high water tables or known sub-grade water issues. $4,489-$9,989.
French Drain Services We Offer
Foundation French Drain
Full perimeter at footing depth, drainage membrane on foundation wall, tie to sump or daylight. $14,500-$32,000. Often combined with drain tile replacement.
Yard Slope Drainage
French drain across the slope to intercept surface water before it reaches the house. 24-36″ depth, ties to storm or daylight. $4,989-$12,989.
Retaining Wall Back-Drainage
Prevents hydrostatic pressure behind new or existing retaining walls. $2,989-$7,989. Critical for long-term wall stability.
Driveway / Patio Sub-Drainage
Below-grade French drains managing groundwater under paved surfaces. Pairs with surface trench drains and catch basins. $4,489-$9,989.
Foundation Wall Waterproofing
If we’re already excavating, we apply Platon or DMX drainage membrane to the foundation wall, sealed at the joints. Often combined with drain tile or French drain. $1,489-$3,989.
Daylight Outflow Construction
Riprap dispersion area for properties without storm sewer connection. 10-foot minimum setback from foundation. Includes splash block and filter to prevent erosion. $389-$789.
Why Vancouver Property Owners Choose Mamba for French Drains
Done Properly - Filter Fabric, Right Drain Rock, Correct Slope
Half the French drain failures we see in East Van are 5-8 year-old installs that skipped filter fabric or used corrugated pipe. We use rigid SDR-35 PVC, Mirafi 140N filter fabric, 3/4″ clear drain rock, minimum 1% slope. 30+ year service life.
City Permits Pulled, Inspections Scheduled
Storm sewer tie-ins require permits. We handle the City of Vancouver paperwork on every install, schedule the inspections, produce certificate of work. Clean compliance record at resale.
Combined With Drain Tile or Other Drainage Work
Already excavating for foundation French drain? Now is the time to also replace drain tile, install a sump pump, or upgrade catch basins. One mobilization, multiple fixes, lower total cost vs. separate projects.
Full Restoration
Drain rock, native soil with filter fabric separator, topsoil, sod or seed, hardscape patches. The yard looks like a yard, not a construction site, when we leave.
Vancouver French Drain Installation Prices
Foundation French drain (full perimeter, 1,500-2,500 sq ft lot): $14,500-$32,000 typically combined with drain tile work.
Yard slope French drain (40-80 ft): $4,989-$12,989.
Retaining wall back-drainage: $2,989-$7,989.
Driveway / patio sub-drainage: $4,489-$9,989.
Foundation wall drainage membrane (Platon / DMX): $1,489-$3,989 (when paired with French drain or drain tile).
Daylight outflow with riprap dispersion: $389-$789.
City permit and inspection coordination: Included in install quotes.
Landscape restoration (sod, shrubs, hardscape): Included in scope.
Heavy access / heritage tree work-around: Custom quote after site assessment.
Wet basement walls every November? Yard turning to mud? French drain moves water before it gets to the foundation.
9 French Drain Tips for Vancouver Property Owners
- Filter fabric is non-negotiable. Lines the trench walls. Without it, native soil migrates into the drain rock and silts the system. #1 reason French drains fail in 5-8 years.
- Use 3/4″ clear drain rock, not pea gravel. Angular shape creates void space for water flow. Pea gravel and crushed limestone have fines that block voids.
- Minimum 1% slope. 1 inch drop per 8 feet of run. Drives water flow without standing water. Less than that and the system silts up fast.
- Rigid SDR-35 PVC, not corrugated HDPE. Corrugated is cheaper but crushes under settling soil over 10-15 years. Rigid PVC lasts 50+ years.
- Footing depth for foundation drains. Surface-depth French drains don’t intercept water before it reaches the foundation wall. Has to be down at footing level (6-9 feet) to actually solve the wet-basement problem.
- Pull the permit. City of Vancouver requires permits for storm sewer tie-ins. Missing permits complicate resale and insurance claims.
- Topsoil separator layer. Filter fabric between topsoil and drain rock prevents soil washing into the drain. Often skipped on cheap installs; critical for longevity.
- Coordinate with other drainage work. If you have drain tile issues or need a sump pump upgrade, do them together with the French drain. One excavation, lower total cost.
- Plan for the tie-in. Storm sewer connection beats daylight outflow if available. Daylight outflow needs 10-foot setback from foundation and riprap dispersion. Some properties tie the French drain to an existing sump system.
Frequently Asked Questions
Same construction, different function. Drain tile sits at the foundation footing and intercepts groundwater before it reaches the foundation wall. French drain handles surface water and slope drainage above grade. Both use perforated pipe in drain rock with filter fabric.
Yard slope drainage 2-4 days. Foundation French drain 5-9 days (similar to drain tile replacement). Retaining wall back-drainage 1-3 days when paired with new wall construction. Permits add 5-10 days from quote acceptance to start.
Yes for any storm sewer tie-in. Yes for any work near or under public sidewalks. No for daylight outflow on private property within setback requirements. We confirm during the site assessment.
Lawn and shrubs along the trench line will be excavated. We restore with sod (or seed if preferred), replant shrubs where root systems allow, restore patio block or hardscape edging. Quote includes restoration cost. Mature trees within 10 feet may need root pruning – we discuss before the job starts.
30-50 years with proper materials and install (filter fabric, drain rock, rigid PVC, correct slope). Premature failures we see in East Van are almost always traceable to skipped filter fabric or undersized drain rock.
Yes – same excavation, lower total cost than two separate projects. We routinely quote them together for full foundation drainage upgrade. See drain tile repair page.
Daylight outflow at least 10 feet from foundation with riprap dispersion. Common in older East Van properties. We design the dispersion area to prevent erosion.
Yes – without back-drainage, hydrostatic pressure builds up behind the wall during wet weather. Even well-built retaining walls crack or rotate forward without proper drainage. Critical for new wall construction; often added during existing wall rebuilds.
Yes – we camera-scope the existing drain to identify the issue. Usually one of three problems: silted with no filter fabric, undersized drain rock, or wrong slope. Sometimes we can rehab in place (hydrojet to clear silt). Often easier to replace properly. Quote after diagnosis.
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QUALITY IS OUR GAME
Mamba Drainage strives to deliver excellence one client at a time by upholding our core values throughout our services. We believe honest and meaningful work creates and sustains the foundation for exceptional client relations.