Foundation Drainage in Tigard, Oregon: Keeping Water Out

Why Tigard Foundations Need Drainage

A wet crawlspace or a damp basement wall is one of the costliest problems a Tigard homeowner can ignore. In Washington County's rolling terrain, the mix of steady wet-season rain, slow-draining clay, and runoff arriving from uphill puts constant pressure on foundations. When water saturates the soil around your footing and has nowhere to go, it pushes against the foundation — and eventually finds a way in.

Foundation drainage is the system that gives that water a path away from your house before it can cause damage. Done right, it keeps crawlspaces dry, prevents basement seepage, and protects the structure from the slow erosion and movement that saturated soil causes over time.

This guide explains how foundation drainage works on Tigard properties, the local conditions that make it necessary, and what goes into a proper system. For statewide pricing, see our foundation drain installation cost in Oregon guide, and for the full picture, our overview of property and site drainage in Oregon.

How Water Gets to Your Tigard Foundation

Hillside Runoff

This is the factor that sets sloped Tigard lots apart from the flat valley floor. Water flows downhill toward homes built into or below a slope, arriving at the foundation in volume during a storm. A house at the bottom of a gentle hill can take on water that originated several lots uphill.

Slow-Draining Clay

Washington County's clay-rich soil holds water against the foundation rather than letting it drain away. Water that lands near the house — or arrives from above — lingers in the clay, keeping the foundation zone saturated long after the rain stops.

Hydrostatic Pressure

Saturated soil holds water that has weight and pushes. This hydrostatic pressure forces moisture through tiny cracks and pores in concrete and masonry. The wetter the soil against the wall, the harder it pushes — and on a slope, the uphill side often stays wettest.

Negative Grade and Roof Runoff

If the ground slopes toward the house, or downspouts dump roof water at the foundation, you are delivering even more water to the exact place you do not want it. Fixing grade and rerouting downspouts is often the first, cheapest line of defense.

How Foundation Drainage Works

Footing Drains (Drain Tile)

The core of exterior foundation drainage is a perforated pipe installed at the level of the footing, surrounded by clean drain rock and wrapped in filter fabric. This footing drain collects water before it builds up against the wall and carries it to a lower outfall. On Tigard's clay lots, the footing drain relieves hydrostatic pressure at the source.

Curtain Drains for Hillside Water

On a sloped lot, a curtain drain across the uphill side intercepts water flowing toward the house before it reaches the foundation. Pairing an interceptor with a footing drain is often the most effective approach on Tigard's hills — stopping incoming water and relieving pressure at the wall.

Drain Rock and Filter Fabric

The gravel envelope around the pipe creates a fast path for water to reach the drain, and the filter fabric keeps fine clay and silt from clogging it. Without fabric, the soil migrates into the gravel and the drain slowly fails — a common reason older systems stop working.

Daylight Outfall or Sump and Pump

The collected water has to exit somewhere. Tigard's sloped lots often have enough fall for the drain to daylight downhill, which is an advantage over the flat valley floor. Where no gravity outfall exists, the drain runs to a sump where a pump lifts the water to a discharge point. Confirming which option your lot allows is central to the design.

What Affects Foundation Drainage Cost in Tigard

Local factors that shape the cost of a foundation drainage project:

• Excavation depth and access — Exposing a footing requires deep excavation, and tight suburban lots or landscaping limit machine access.
• Hillside interceptor — Adding a curtain drain on the uphill side adds trench and pipe but often prevents the worst problems.
• Sump and pump vs. gravity outfall — Lots that can daylight downhill cost less than those needing a pumped discharge.
• Linear footage — Wrapping more of the foundation perimeter means more trench, pipe, and rock.
• Restoration — Replacing hardscape, landscaping, or walkways disturbed during the dig adds to the total.

For statewide baseline ranges and how each factor moves the number, see our foundation drain installation cost in Oregon guide. The only accurate figure comes from an on-site assessment of your foundation, soil, slope, and outfall options.

When to Call a Pro in Tigard

Foundation drainage is not a DIY project. It involves deep excavation against the structure, precise slope to the outfall, and judgment about hillside water and soil that comes from experience. Signs you should get a professional assessment include a damp or wet crawlspace, water stains on basement walls, efflorescence (white mineral deposits) on concrete, musty odors, or water collecting against the uphill side of the house after rain.

The earlier you address it, the cheaper it stays. Chronic saturation does not just cause a wet basement — over years it can undermine the soil that supports your footing, a particular risk on a slope. A drainage contractor who assesses your site can tell you whether you need a footing drain, a hillside interceptor, grading and downspout work, or a combination.

Get Your Tigard Foundation Drainage Quote

Cojo Excavation & Asphalt installs footing drains, curtain drains, and foundation drainage systems for Tigard and Washington County homeowners. We assess your foundation, soil, slope, and outfall options on site, then deliver a clear, no-obligation quote for a system built to keep water out.

Request a free drainage estimate and we will respond within 24 hours. Learn more about our excavation services and how we protect Tigard homes from wet-season water.