Drain Tile (Footing Drains) for Oregon Homes

The Drain That Protects Your Foundation

In Oregon's wet climate, the ground around a foundation spends much of the year saturated. That water presses against basement and crawlspace walls, finds the smallest gap, and ends up inside. Drain tile — a perforated pipe ringing the base of the foundation — is the system that relieves that pressure and carries the water away before it gets in.

Despite the old-fashioned name (early versions really were clay tiles), modern drain tile is perforated pipe in a gravel envelope. It's one of the most important and least visible parts of keeping an Oregon home dry. This guide covers how it's installed. For the broader picture, see our Oregon drainage guide.

What Drain Tile Does

Drain tile sits at the footing level — the bottom of the foundation — and rings the perimeter. Its job is to intercept groundwater before it can build up against the foundation wall and to relieve the hydrostatic pressure that pushes water through concrete and into the structure.

Water in the surrounding soil seeps into the gravel, drops into the perforated pipe, and flows by gravity to an outfall. By keeping the water table around the footing low, drain tile protects the wall from both leaks and the long-term pressure that cracks foundations. For pricing, see our foundation drain installation cost guide.

Exterior vs. Interior Drain Tile

There are two approaches, and they solve the problem from different sides:

• Exterior drain tile is installed outside the foundation at the footing, intercepting water before it ever reaches the wall. It's the preferred approach because it stops water on the outside, but on existing homes it means excavating down the full depth of the foundation.
• Interior drain tile runs inside the basement, under the slab edge, catching water that has already reached the wall and routing it to a sump pump. It's less invasive on a finished home but treats the symptom rather than keeping water out entirely.

This article focuses on exterior drain tile, the gold standard for keeping water away from an Oregon foundation.

Depth: At the Footing, Not Above It

The single most important detail is depth. Drain tile has to sit at or just below the top of the footing. Place it too high and it never intercepts the water that's pressing against the lower wall — water rises past it and still gets in. The pipe should ring the footing at the right elevation, with continuous slope around the perimeter toward the outfall.

That depth is why exterior drain tile on an existing home is a significant excavation: you're digging down the entire height of the foundation to reach the footing.

The Gravel Envelope and Filter Fabric

Like any subsurface collection drain, drain tile lives in a gravel envelope of clean, washed drain rock. The gravel gives water a free path into the pipe and is as much a part of the collection as the pipe itself.

And like any drain in Oregon's fine soils, it needs filter fabric to survive. The trench and gravel are wrapped in geotextile so silt and clay can't migrate in and clog the system. Without fabric, fine soil fills the gravel voids and slots, and the drain quietly fails within a few years. This is non-negotiable in clay-heavy ground. The same fabric-and-gravel principle applies to French drains — see how they compare in our footing drain vs French drain guide.

How Exterior Drain Tile Is Installed

1. Excavate down to the footing around the foundation perimeter.
2. Lay filter fabric in the trench.
3. Add a base layer of drain rock and set the perforated pipe at footing level, sloped toward the outfall.
4. Surround the pipe with more drain rock, then wrap the fabric over the top of the gravel envelope.
5. Apply or inspect foundation waterproofing on the wall while it's exposed — a rare chance to address the wall itself.
6. Backfill carefully, often with free-draining material against the wall.
7. Route the outfall to daylight, a dry well, or a sump.

Because the foundation wall is exposed during the dig, exterior drain tile installation is also the ideal moment to waterproof or repair the wall.

Where the Water Goes

Drain tile, like every drain, needs an outfall. On a sloped lot it can daylight downhill by gravity. On a flat lot, it may need to route to a dry well or a sump pump that lifts the water out. Without a working outfall, the drain tile just fills and stops protecting the foundation.