Paving-related drainage in Vancouver, WA and Clark County

Sloping concrete so water runs off

Most drainage is built into the shape of the concrete. The residential building code calls for hard surfaces within 10 feet of a house to slope away from it at 2 percent, about a quarter inch per foot, so rain runs into the yard instead of toward the foundation. Driveways are pitched toward the street or a drain.

Trench drains and catch basins for low spots

Where slope alone can’t do it, like a driveway that runs down toward the garage, a trench drain across the concrete catches the water and carries it away in a pipe. A catch basin does the same at a single low spot.

Piping downspouts and runoff

Downspouts that dump onto a driveway or patio leave it wet, green and slick. They can be piped under the new concrete to a spot that can take the water. The easiest time to do it is before a pour, while the ground is open.