Drainage for a Driveway

Foundation Drainage

• The best time to prevent driveway drainage problems from developing is during installation. Keep the type of soil you have in mind when building up the gravel foundation. The depth of the foundation must be as deep as necessary to remove all topsoil and lay the base over hard dirt, which is typically 12 inches deep. If the subsoil feels loose or sandy even after it’s compacted, lay down geotextile fabric to reinforce the base and act as a filter against silt. Layer the gravel foundation beginning with large gravel and ending with small gravel. Compact the gravel between each layer so the rocks wedge firmly together, allowing just enough room for water to drain.

Pavement Drainage

• All driveways should have a slight slope with the highest end near the house and the lowest end adjacent to the street. If the front yard is completely flat, you can create this slope by digging the foundation at a 2 percent slope, or 1/4 inch down for every foot of distance. In addition to pitching the length of the driveway so water runs toward the curb, install a slope across the width of the driveway so water only runs down the side of the driveway furthest from the home.

Underground Drain Pipes

• Installing a basic underground drainage system beneath the pavement can be done during installation or to an existing driveway. If laid during installation, set a channel drain over gravel down the center of the driveway. Lay the grating over the pipes and caulk the joints with PVC cement so water can’t seep into the foundation. For an existing driveway, identify the spot where water stands on the surface. Cut through the pavement and dig out a drain trench that runs across the driveway through the problem spot. Lay a drain pipe in the trench and connect it to another pipe running alongside the driveway. Pave over the trench with bricks to disguise the pipes while making them easy to access.

Side Drain System

• Laying a drain pipe along the low side of a driveway helps prevent underground water from damaging the driveway foundation. Lay the pipes 12 feet underground and about 6 inches from the side of the driveway. Set the pipes over gravel and shift the gravel to slope down 1 inch per every 8 feet so water will quickly flow to the street. Cover the pipes with gravel and plant flood-resistant grass on top.