Proper Asphalt Driveways

Prepare Site

• The stability of an asphalt driveway depends upon the quality of the base and subbase. You must excavate the site to a minimum depth of 1 foot with a slight slope toward the curb so water naturally drains away from the yard. Before building up the base, you must compact the subsoil to force out excess moisture and air pockets. If your soil has a clay consistency, lay down landscape cloth over the dirt to prevent the base from sinking or deforming under pressure.

Foundation

• Foundations for an asphalt driveway are in two types, depending on your soil type. A gravel foundation is made of 3/4-inch crushed rocks tamped to form a base layer at least 8 inches thick. A gravel foundation allows underground water to travel away so it doesn't weaken the foundation or cause frost heave damage. For a yard with heavy clay soil, mix large gravel with asphalt and spread it over a thin layer of gravel. An asphalt base provides more support under heavy weight loads and doesn't sink.

Paving

• The types of asphalt paving mixes vary by the type and size of aggregate they contain and the quality of cement. Asphalt is typically paved in two layers. The first layer should be about 2 inches thick and contain medium or large aggregate. The top layer is about 1 inch thick and should have smaller aggregate for a smoother appearance.

Maintenance

• Asphalt driveways require patience when it comes to maintaining them. After installation or re-paving the surface, wait six months before applying sealer to allow it to cure properly. Sealer should go on in two or three thin coats so it can penetrate into the material. In addition to repelling water and preventing cracks, sealer slows the fading process.