Building a road on a slope requires careful planning and will normally require a drainage system underneath to prevent flooding and damage to the road over time. Your professional may lengthen your road to create switchbacks if the slope directly to your home is too steep, as there are regulations for maximum road slope. The drainage system will help prevent runoff from the higher side of the slope from damaging the asphalt or concrete. Keep in mind that building a road on a slope isn’t a good DIY project, as a lot can go wrong.

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.

Gravel is one of the few driveway materials that can handle rain the second it’s installed. Unlike asphalt, which needs days to set, or concrete, which requires weeks to cure, gravel is ready as soon as it’s compacted. It’s naturally permeable, allowing water to drain straight through—with no risk of pooling or surface damage. Gravel driveways are one of the most affordable, at $1 to $3 per square foot, and can also last upward of 100 years.

While blacktop is a type of asphalt, the terms should not be used interchangeably, as not all asphalt qualifies as blacktop. The primary differences are in their composition, production process, and ideal applications. Blacktop contains more stone than other types of asphalt and is heated to a higher temperature during production—300°F or more—while hot-mix asphalt is heated to between 275°F and 300°F. The ratio of bitumen (a tar-like crude oil) is a key differentiator, though sources vary: some state blacktop has less bitumen, making it less durable, while others claim it has a higher ratio. Due to these differences, asphalt is generally more durable and better for high-traffic areas like highways and streets, while blacktop is more suitable for playgrounds and residential driveways. For a driveway project, it is best to consult a professional to determine the most appropriate material.