Landscaping & Drainage in King County

Landscaping & Drainage in King County specifically

The drainage principle is the same everywhere in Washington — get roof and surface water away from the building. What differs in King County is how hard that is to achieve.

On a suburban lot, a downspout extension moves water far enough that it soaks away harmlessly. On a Seattle lot with a narrow side yard and a neighbour's fence a short distance from the wall, the same extension moves water a few feet and it returns. The cheap fix that works elsewhere frequently does not work here.

That pushes King County solutions toward buried lines carrying water to a legitimate discharge point, which is a real piece of work rather than an afternoon's job. Where that discharge point is, and whether it is permissible, becomes the design question — and it is worth establishing before quoting rather than after.

Mature tree canopy is the second constraint. Root systems from established conifers make trenching more complicated and can rule out routes that look straightforward on a plan. Roots also seek out drainage lines, so material choice and detailing matter for longevity.

The third is slope, or its absence. Much of the developed county is flat enough that gravity provides little help, which means fall has to be created rather than exploited, and shallow runs need more care to work reliably.