Asphalt
New Asphalt Driveway Installation in Hillsboro, Oregon
Cojo
May 30, 2026
7 min read
A new driveway is a major upgrade for a Hillsboro home, but the job is only as good as what goes in below the surface. Washington County's Tualatin Valley clay and the region's long wet season mean the base and drainage do the heavy lifting on whether your driveway lasts a couple of decades or starts cracking in a few years. Get those right, and the asphalt on top performs.
This guide walks Hillsboro homeowners through the full installation so you know what a quality job looks like and what to ask for. For the general mechanics that apply statewide, see our step-by-step asphalt driveway installation process, and for pricing, our asphalt driveway cost in Hillsboro page.
The crew measures the area, checks the grade, and plans drainage. In Hillsboro's wet climate over clay soil, this is the most important step — water has to be directed away from the driveway, not allowed to sit under it.
The native clay is dug out to make room for the base. The crew checks for soft, saturated spots that need extra work.
The exposed sub-grade is graded and compacted. Over expansive clay, contractors often place a geotextile fabric here to separate the base rock from the clay and keep the two from mixing under load.
Crushed aggregate base is spread and compacted to the right depth for residential traffic. On clay, base depth and drainage matter even more than usual — this layer is what isolates the surface from the moving ground beneath.
Hot-mix asphalt is laid, typically in a binder course and a surface course, then rolled immediately while hot to reach full compaction.
Heavy rollers compact the asphalt to a dense, smooth surface. Edges are shaped and transitions to the garage slab or road approach are finished cleanly. Edge support matters on clay, where unsupported edges crumble first.
The new driveway needs time to harden. Light use usually resumes within a few days; heavier vehicles and the first sealcoat should wait — typically several months.
Where your driveway meets a public street, you may need a driveway approach permit through the City of Hillsboro or Washington County, depending on jurisdiction. The approach must meet local standards for sight lines, drainage, and how it ties into the road. A contractor who works in the area will know which agency has authority and handle the permit.
Tualatin Valley clay swells and shrinks with moisture. A new driveway built for Hillsboro uses a deep, compacted base — often over geotextile fabric — and positive drainage so water moves away rather than soaking into the ground under the slab.
The long rainy stretch keeps the ground saturated and limits when paving can happen. Asphalt needs dry, warm conditions to cure properly, so installs are scheduled within the summer window.
On clay, driveway edges are the first to fail if they aren't supported. A quality install accounts for edge stability so the perimeter doesn't crumble.
Even a thorough site visit can't reveal everything underground. Common surprises in Hillsboro installs include:
These unknowns are why a site-specific quote beats any average. A contractor who evaluates your clay and grade gives a far more accurate price and timeline.
Most residential installs take two to four days of active work, weather permitting. Schedule within the dry window — late spring through early fall — so the asphalt cures properly and the ground is firm. For the bigger picture, start with our complete asphalt driveway guide for Oregon. If you have an existing driveway rather than a blank lot, compare driveway resurfacing in Hillsboro and driveway replacement in Hillsboro.
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