In Snohomish County, French drains are one of the most common solutions for yard drainage, foundation moisture, and standing water problems. Ivan’s Landscaping & Construction helps homeowners address these issues by installing properly designed drainage systems built for local soil and rainfall conditions. On average, exterior French drain installation costs between $35 and $42 per linear foot, which typically includes excavation, pipe installation, gravel, and labor. Interior French drains, such as those installed in crawl spaces or basements, usually cost about double due to tighter work areas, added manual labor, and interior drainage components.
These price ranges reflect real-world excavation and drainage work common throughout Snohomish County properties and the types of projects Ivan’s Landscaping & Construction completes throughout the year.
Full Breakdown of Costs to Install a French Drain
French drain pricing depends on how the system is built, where it is installed, and what conditions crews encounter during excavation. Ivan’s Landscape & Construction knows what affects total cost and why pricing can vary from one property to another.
Type of French Drain
The type of drain pipe and filtration system used plays a major role in both material and labor costs. Common options include PVC or corrugated pipe and styrofoam-wrapped perforated pipe. PVC offers rigidity and long-term durability, while corrugated pipe is more flexible and easier to work with in curved or uneven trenches. Styrofoam-wrapped systems combine filtration and pipe into one unit, which can speed up installation in some exterior applications.
French Drain Labor Costs
Labor covers trench excavation, proper slope setup, gravel placement, pipe installation, and backfilling. Graveling the perforated pipe is a critical step that helps keep sediment out and maintains proper water flow. Labor costs increase when access is limited, trenches are deeper, or soil conditions slow excavation.
Size and Depth of the Drain (Excavation)
Longer and deeper drains require more excavation and material. A shallow yard drain costs less than a deep trench installed near a foundation or footing. Depth affects how much soil must be removed, handled, and compacted, which directly impacts labor time.
Interior or Exterior French Drain
Exterior French drains are generally more straightforward and follow standard excavation methods. Interior French drains typically use thin-wall PVC (HDPE high-density polyethylene) or corrugated pipe. These systems often include drainage boards or wall channels to guide water into the drain. Interior installations involve tighter spaces and more manual labor, which increases overall cost.
Soil Type
Soil conditions have a direct impact on pricing. Wet soil, clay-heavy ground, or compacted dirt common in parts of Snohomish County can slow excavation and handling. In these cases, total project cost can increase by 10% to 15% due to added labor and time.
Permits
Some French drain projects require permits depending on size and location. Snohomish County may require an LDA permit (Land Disturbing Activity) if the project involves significant soil movement or if the property is near a wetland or stream. Permit requirements and drainage plan information can be found here.
French Drain Cost Per Linear Foot
Understanding cost per linear foot helps homeowners estimate total pricing based on the length of drain needed. While per-foot pricing provides a solid baseline, factors like depth, soil conditions, and interior versus exterior placement can still shift the final cost.
Exterior French Drain Cost Per Linear Foot
Exterior French drains in Snohomish County typically range from $35 to $42 per linear foot. For example, a 50 linear foot exterior French drain generally costs around $1,750 for excavation and labor, depending on site conditions and access.
Interior French Drain Cost Per Linear Foot
Interior French drains usually cost about 1.7 times more than exterior systems. This increase reflects manual excavation, tighter working conditions, and the use of interior drainage boards or wall channels commonly installed in crawl spaces and basements. Once materials and labor are combined, interior systems fall into a higher per-foot range than exterior installations.
Hiring a Professional for French Drain Installation in Snohomish County, Washington
French drain systems require proper slope, placement, and materials to work long term. Hiring a professional helps prevent drainage failures, water intrusion, and repeat repairs.
If you are planning a drainage project, Contact Us at Ivan’s Landscaping & Construction to learn more about our French drain installation services in Snohomish County and schedule a consultation.