French drain installation in Seattle
Move water off the yard and away from the foundation with solid PVC, proper slope, and a clear discharge—scoped after we see how your property loads in PNW rain.
NDS-certified. Active diversion—not a shallow gravel ditch.
We do French drain installation in Seattle, Lynnwood, Everett, Bellevue, and Snohomish County for wet yards and foundation perimeters—engineered collection and discharge, not corrugated pipe dropped in a shallow trench.
Signs the water needs a drain line
Yard water and foundation load look different on the surface. These patterns usually mean collection and diversion—not another coat of paint.
One wet wallHillside or yard runoff loading the same elevation
Perimeter failureSeepage tied to missing or clogged footing drains
A perforated pipe in washed gravel moves groundwater and yard water to a safe outlet before it presses the slab and walls. In Puget Sound soils—especially glacial till and clay—that often means a deeper trench, washed rock, filter fabric, and solid PVC with real slope to daylight, storm, dry well, or a sump.
If the living basement is already wet, start with our wet basement bridge to read the water path. The drain is often part of the fix—not always the whole system.
Interior vs exterior drains
Same name in search. Different jobs on your house. We confirm which path—or mix—after inspection.
Exterior / footing drain
Excavated outside the wall at footing level to intercept groundwater before it enters. Best when access allows digging and the load is outside the envelope—often paired with foundation waterproofing.
Interior perimeter drain
Collected along the slab edge inside the basement or crawlspace, usually tied to a sump pump. Best when exterior access is blocked or floor water is the main symptom.
Many Puget Sound homes need a sequenced mix. Compare details in our interior vs exterior Field Manual—then hire from this page after we inspect.
Inspection first, then a system that drains
NDS-minded details: depth, slope, rock, fabric, solid PVC, and a discharge that leaves the problem zone.
Map the water
Grade, downspouts, existing drains, soil conditions, and where water actually shows up after a Seattle rain.
Design the run
Trench path, depth, slope, washed rock, filter fabric, solid PVC (not soft corrugated), and discharge to daylight, storm, dry well, or sump.
Install & walkthrough
Excavation or interior slab cut as scoped, cleanouts where useful, then how the system should behave in a heavy storm.
Design rule we do not break: never tie roof downspouts into a perforated drain line. Roof water runs in solid pipe on its own line—see our downspout rule FAQ.
Get an on-site read of runoff vs. groundwater—then a clear drainage scope and written estimate.
What you get with this service
Unit-based scope after we see the property—not a one-size “drain package.”
- Site evaluation of grade, downspouts, existing drains, soil, and discharge options
- Written scope for exterior footing work, interior perimeter collection, and/or yard runs as needed
- Solid PVC design with proper slope—never tying roof downspouts into the perforated line
- Coordination with basement waterproofing or sump work when the water path needs more than a trench
Price follows scope: interior vs exterior, trench length, access, landscaping or concrete restoration, soil, and whether a sump or discharge upgrade is required. After a free site visit you get a written estimate matched to the water path.
City pages and yard drainage
This page covers French drain installation in Seattle and the wider metro. These pages go deeper by city and yard scope.
Yard drainage Bellevue
Catch basins, grading, and yard collection when the Eastside lawn stays wet.
Yard drainage Everett
Snohomish County yard runoff and surface diversion scoped to the lot.
Yard & downspout guide
Field Manual on roof water, grading, and why downspouts stay off the perforated line.
Puget Sound coverage
Based in Lynnwood. Drain installation across Greater Seattle, the Eastside, and Snohomish County.
We serve Seattle, Bellevue, Everett, Shoreline, Kirkland, Redmond, Edmonds, Bothell, Marysville, and nearby communities. See service areas for the full map, or start at the Basement Expert homepage.
Drainage questions
Short answers before you schedule. We confirm scope on site.
What is a French drain and how does it work?
A sloped trench with washed gravel and a perforated pipe that collects groundwater or yard water and moves it to a safe discharge point. In Seattle-area soils we use it for wet yards, perimeter footing drainage, and interior basement collection when tied to a sump.
Do I need an interior or exterior drain?
Exterior footing drains intercept water outside the wall when excavation is practical. Interior perimeter drains collect at the slab edge and usually discharge through a sump when access is limited or floor water dominates. Many homes need a sequenced mix—we confirm on inspection.
Should downspouts connect into the perforated line?
No. Roof water belongs in solid PVC lines routed separately. Connecting downspouts into a perforated drain can overwhelm the gravel bed and back-flood the system.
What does the install cost?
Cost depends on interior vs exterior scope, trench length, access, soil, landscaping restoration, and whether a sump or discharge upgrade is required. We give a written estimate after a free site visit.
How long does installation take?
Many residential jobs finish in about one to three days once work starts. Full exterior excavation, complex discharge routing, or finished-basement restoration can take longer. We confirm duration after inspection.
Will a drain line alone fix a wet basement?
Sometimes for yard and perimeter water. Under-slab hydrostatic pressure or wall seepage may also need basement waterproofing, sump capacity, or discharge corrections. A drain line is one tool in an inspection-first plan.
Which areas do you cover?
We install across Greater Seattle, the Eastside, and Snohomish County from our Lynnwood shop. Check our service areas map or call to confirm your address.
Ready for a drain that actually discharges? Schedule a drainage inspection with Basement Expert.
Serving Puget Sound from Lynnwood — see all services.
