An asphalt driveway should be at least 3 inches thick over a compacted gravel base. Areas with poor drainage should have a thicker stone base. To install a new asphalt driveway over an existing driveway, the new asphalt should be at least 2 inches thick and the existing driveway should be in relatively good condition.

Driveways should be sloped with a minimum 2% slope—anything lower will cause precipitation and runoff to collect. A 2% slope is the equivalent of a 2-foot rise over 100 feet. One quick way to check the integrity of your driveway’s slope: no more than four inches of water should collect on the surface longer than 15 minutes after rain.

Maintaining a driveway depends on its material. For concrete and asphalt, it's best to clean the surface thoroughly twice a year with a stiff broom and a pressure washer to remove accumulated dirt and debris. Sealing the driveway is crucial to protect it from water damage and freeze-thaw cycles. Before applying a sealant, pressure wash the surface to remove any loose sealant, dirt, or stains, as sealing over them will trap them. Any cracks or expansion joints should be filled with a flexible polyurethane caulk or asphalt sealer. In colder climates, use sand instead of salt for de-icing. Sand helps melt snow and ice without accelerating the freeze-thaw process, which can cause cracks.

Your city or county will have guidelines about the minimum and maximum width and length of private roads. The average private road is 12 feet wide, and length, of course, depends on your property. Requirements also depend on the amount of traffic and types of vehicles your road experiences. Check with local ordinances before planning a road on your property.