Asphalt Driveway Paving in Union City, CA

Asphalt driveway paving is mostly groundwork. The black surface is a few inches thick; under it sits a compacted rock base and, under that, native soil. In Union City that soil is often clay that swells in the wet months and shrinks in the dry ones. When a driveway here breaks into a web of cracks, settles by the garage or lifts along one edge, the cause is almost always the base, the subgrade or water with nowhere to go. A new driveway fixes those first.

Signs a driveway needs replacing

• Cracks joined into a pattern that looks like alligator skin
• Potholes that come back after patching
• Low spots that hold water after rain
• Edges crumbling into the planter strip or lawn
• More patch than original pavement

A few separate cracks can be sealed and a small failed area can be patched. When problems cover much of the surface, replacement usually costs less over the next ten years than repeated repairs.

Building on expansive soil

Union City's general plan geology study rates the Rincon and Clear Lake clay soils found in the city as moderately to highly expansive. On a driveway that means seasonal heave and settlement. We dig out soft or pumping subgrade, replace it with compacted crushed rock, and grade the base so the finished surface sheds water toward the street or a drain instead of toward the garage or the foundation. Where a downspout empties onto the driveway, we talk about redirecting it, because a constant water source at the edge is one of the fastest ways to soften clay.

Thickness and materials

Cost guides describe a typical residential driveway as 2 to 3 inches of compacted asphalt over 6 to 8 inches of compacted gravel, and 3 to 4 inches of asphalt over 8 to 10 inches of base for driveways that carry trucks, trailers or RVs. Your quote states the base depth and the compacted asphalt thickness so you can compare bids on the same terms. Hot-mix asphalt is spread with a paver where access allows and rolled while it is still hot enough to compact.

The garage, the walk and the apron

Three transitions decide how a driveway looks and drains: the garage slab, any walkway, and the concrete apron at the street. At the garage we taper the asphalt to meet the slab without a lip. At the apron, remember that in Union City the public right-of-way begins at the property line. If your project only replaces the driveway up to an existing apron, no encroachment permit is usually needed. If the apron, curb or sidewalk is part of the job, the city requires a Public Works encroachment permit, and we explain what that involves before anything is scheduled.

Caring for a new driveway

New asphalt stays soft for its first warm season. Avoid turning the steering wheel while parked, vary where you park, and put a board under motorcycle stands and trailer jacks. Wait several months before the first sealcoat, then seal every few years and fill cracks before the rains start in November.