Ground, water and winter in Concord
South county sits on rolling upland with the clay-heavy soils common around St. Louis, and parts of the county near the rivers are karst ground with sinkholes and springs. Clay swells and shrinks, freeze-thaw lifts trapped water, and both crack pavement. Drainage and compaction come ahead of thickness.
When you compare bids, ask each contractor for three numbers in writing: the compacted asphalt thickness, the base depth, and what happens to the water. Those three decide how long the surface lasts.
Compacted asphaltTypically 2 to 3 in. for a car drive
Stone baseTypically 4 to 8 in., compacted
Drive on itUsually 2 to 3 days, longer in heat
First sealcoatTypically 6 to 12 months after paving
Typical ranges. Your Concord estimate is sized to the soil, the traffic and the drainage on your property.