Hardscaping in Washington That Drains Where It Lands

What we build across Washington

Paver patios and retaining walls carry most of the work in this state. Patios sit on 5/8 minus and drain to a rain garden or daylight line. Retaining walls hold back hillside lots where daylight basements are common. The crew assigned to your job builds both with the same base discipline.

• Paver patios for covered patios and open seating areas
• Retaining walls for terraced yards and hillside lots
• Walkways and steps that route water away from foundations
• Grading and drainage to move runoff before it pools
• Paver driveways built as permeable systems where rules require
• Gravel driveways on 5/8 minus for long rural access

How a Washington job goes

You get a written price before anyone digs. The quote covers the base depth, the wall engineering, and the drainage detail. That price comes from your site conditions, not a guess.

Once you accept, the crew sequences the work: dig, set the base, compact in lifts, then place the surface. You need to be present at the start to confirm lines and grades. You do not need to be there for the base compaction or the paver installation. The process page walks through each step. The cost guide explains what drives the number in this region.

The rules on runoff in Washington

Stormwater rules shape how much of a lot can shed water. In Seattle and King County, and across the Eastside, new hardscape must keep runoff on site. A permeable driveway or patio lets rain soak into the ground instead of sending it to the street. That is why permeable systems exist: they count differently than solid concrete or asphalt.

Impervious surface is the term that matters. A solid patio sheds nearly every drop that hits it. A permeable paver system with an open base does not. The difference decides whether your project needs extra detention or a rain garden.

In Tacoma and Pierce County, hillside lots add another layer. Water moving down a slope has to be caught and directed before it reaches the wall or the daylight basement. In Spokane and eastern Washington, basalt close to the surface changes the dig, and volcanic soils drain faster, but the runoff rules still apply where new hardscape goes in. The design starts with where the water goes, then the surface goes on top.

What a permeable system is made of

Permeable pavers sit on an open-graded base, not solid 5/8 minus. The open base has void space that holds water and lets it soak into the soil below. Standard patios and driveways use compacted 5/8 minus, the crushed surfacing base course specified by WSDOT. The yard and contractor name for it is 5/8 minus, and that is how material is specified locally.

Under permeable pavers, the base layer is thicker and the stone is washed so fines do not clog it. Water passes through the paver joints, into the base, and down to the native soil. Where the soil is clay, the system needs an underdrain to move water sideways to a rain garden or daylight line. Where the soil is sand, as at the coast, water moves through faster and the base can be shallower.

Grading carries the rest of the job. The surface slopes to catch basins or a planted swale, never back toward the house. The season window runs year round in the Puget Sound lowlands, with a slow stretch in the wettest winter weeks. East of the Cascades, the season runs roughly April to November because frozen ground stops compaction.

The dig, the base and the season

Stormwater rules and hillside lots put permeable detail and wall engineering into the price. A retaining wall on a slope needs geogrid tied back into the soil, and that costs more than a wall on flat ground. Permeable driveways need a thicker base and careful grading, which adds machine time.

In the east, basalt in the dig adds machine time. Breaking through rock slows the excavation and raises the cost of the base work. The season also sets the pace. Wet weeks in the lowlands slow compaction, and frozen ground east of the Cascades stops it entirely.