If you have received a waterproofing quote that includes a French drain, or if you have been researching drainage solutions and keep seeing the term, you probably want two things: to know what it is going to cost, and to know whether it is actually the right solution for your home.
Both are fair questions. Here is an honest breakdown of French drain installation costs in Portland for 2026, what drives those costs up or down, and when a French drain is and is not the right tool for the job.
WHAT IS A FRENCH DRAIN?
A French drain is a gravel-filled trench containing a perforated pipe that collects and redirects groundwater or surface water away from a specific area. Named after Henry French, who popularized the concept in the 1800s, it is one of the most time-tested drainage solutions in residential construction.
There are two main types used in Portland-area homes:
Exterior French drains are installed in the yard or around the perimeter of the foundation to intercept surface water or shallow groundwater before it reaches the house. They are commonly used to address yard drainage problems, water pooling near the foundation, or water that collects in low spots.
Interior French drains (also called interior perimeter drainage systems are installed inside the basement along the floor perimeter to capture water that has already entered through the walls or floor. Despite the shared name concept, interior systems are a different product, designed specifically for active basement water intrusion.
When a contractor mentions a French drain in a waterproofing quote, it is important to clarify which type they mean.
FRENCH DRAIN INSTALLATION COST IN PORTLAND: PRICE RANGES
Costs vary significantly based on the type, length, depth, and complexity of the installation.
Exterior French drain (yard or perimeter):
- Simple surface drain (shallow, short run): $1,500 – $4,000
- Full perimeter exterior drain (around foundation): $8,000 – $20,000+
- Interior French drain / perimeter drainage system: $4,000 – $12,000
The most common exterior French drain project in a Portland yard, addressing a single drainage problem or redirecting runoff from a specific area, typically costs between $1,500 and $5,000 depending on length and depth.
Full exterior perimeter drains that run around the entire foundation are significantly more expensive because they involve more excavation, more pipe, and more material. They are typically not needed for most Portland homes unless there is a specific groundwater problem that cannot be addressed from inside.
For interior basement drainage, see our dedicated sump pump and interior drainage cost guide for Portland-specific pricing.
WHAT DRIVES THE COST UP OR DOWN
Length of the drain run
The longer the trench, the higher the cost. Most French drain quotes are priced per linear foot. In Portland, expect to pay $30 to $70 per linear foot for a standard exterior installation, not including any concrete cutting, landscaping restoration, or specialty materials.
Depth of excavation
Shallow surface drains that sit just below the grass line are less expensive to install than deep drains that need to go below the frost line or intercept groundwater at depth. Deeper trenches require more labor and more material.
Outlet location
The drain pipe needs somewhere to discharge, a storm drain, dry well, or daylight outlet on a slope. If the outlet requires a long run of pipe or involves tapping into an existing drainage system, this adds cost.
Landscaping and hardscape restoration
If the drain runs under a lawn, the restoration cost is minimal. If it runs under a patio, driveway, or established landscaping, the cost of restoring those surfaces after installation adds significantly to the total.
Portland’s clay soil
Portland’s clay-heavy soil is dense and difficult to excavate compared to sandy or loamy soils. This increases labor time and therefore cost. It also means that drain pipe and gravel specifications matter more, clay soil can clog improperly installed French drains faster than in better-draining soil types.
WHEN A FRENCH DRAIN IS THE RIGHT SOLUTION
A French drain is appropriate when the problem is surface water or shallow groundwater that needs to be intercepted and redirected.
Good candidates for a French drain:
- A low spot in the yard that consistently pools water after rain
- Surface runoff from a neighboring property or uphill slope that drains toward your foundation
- A damp basement where the cause is groundwater building up around the exterior of the foundation
- Soggy turf or garden areas that never fully dry out
When it is not the right solution:
- Active water intrusion through basement walls or the cove joint caused by hydrostatic pressure — this requires an interior drainage system, not an exterior French drain
- Crawl space moisture that comes primarily from ground evaporation, this requires a vapor barrier or encapsulation, not excavation
One of the most common mistakes we see is homeowners spending on exterior French drains when their basement flooding problem is caused by hydrostatic pressure that an exterior drain will not adequately address. A professional inspection before any drainage work is the most important step. Read our comparison of interior vs exterior waterproofing for Oregon homes to understand which approach applies to your situation.
HOW TO EVALUATE A FRENCH DRAIN QUOTE
When getting quotes from Portland contractors, here is what to ask:
Is this an interior or exterior French drain? The distinction matters enormously for both cost and effectiveness.
What is the outlet for the drain? A drain that has no outlet or that discharges somewhere that will cause new problems is not a complete solution.
What happens to my landscaping or hardscape? Get restoration costs included in the quote or clearly estimated separately.
What is the warranty on the installation? A properly installed French drain should last 20 to 30 years with minimal maintenance.
Is the contractor licensed with the Oregon CCB? Verify any Oregon contractor’s license at the Oregon Construction Contractors Board before signing anything.
For a full picture of what waterproofing your Portland basement or crawl space costs, see our complete waterproofing cost guide.
GET A FREE DRAINAGE EVALUATION
If you have been quoted a French drain and want a second opinion, or if you are not sure whether it is the right solution for your yard or basement, we are happy to take a look at no cost.
At Better Basement and Waterproofing, our inspections are free and come with an honest written estimate. We will tell you exactly what the right solution is for your specific situation.
Schedule your free inspection here
Better Basement and Waterproofing serves Portland, Eugene, Vancouver, and surrounding communities in Oregon and Washington.
