Get matched with top paving pros in Chestertown, MD

Asphalt and tarmac are not the same thing. Traditional tarmac, short for tarmacadam, uses tar as a binder to hold crushed stone together. Asphalt uses bitumen—a byproduct of crude oil—to bind aggregate. Though tarmac was once a go-to for roads, asphalt has become the modern standard. And these days, most surfaces referred to as “tarmac” are actually asphalt. So, while the names may overlap, the key distinction lies in the binder—tar for tarmac and bitumen for asphalt.

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.

Professional installers often include a deep layer of crushed gravel under permeable pavers to allow more runoff to soak through into the soil below. Many installations will include multiple layers of gravel, with coarser aggregate at the base and finer aggregate that sits on top of that bottom layer. Above the gravel, you’ll often find coarse sand that helps reduce paver shifting over time. Some permeable paver designs include a water collection system set into the gravel layer to route runoff to a safe area for disposal.

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.