Asphalt Driveway Paving in Fort Collins, CO

Asphalt driveway installation means building a new drive, or replacing a worn one, from the subgrade up: excavation, a compacted aggregate base, hot-mix asphalt placed and rolled, and a concrete approach at the street where the county standards require one. In Fort Collins the design has to reckon with a 30-inch frost depth in the city's building code, clay subgrades such as the Nunn series, and a paving season bounded by cold nights at both ends. A paving contractor who works here should talk about base depth and drainage before thickness, because a drive over wet clay fails from below no matter how much asphalt sits on top.

HomeGuide describes a typical residential driveway as 2 to 3 inches of asphalt over 6 to 8 inches of compacted gravel base, a reasonable starting point for a drive that carries cars. Clay changes the conversation. The county street standards require swell testing whenever soil samples show probable expansion above 2 percent, and the Colorado Geological Survey notes that natural swelling soils seldom grow past 1.5 times their original volume, which is still enough to crack slabs and drives. Over high-clay ground, a contractor may recommend over-excavation, a deeper base or drainage work; over the well-drained Fort Collins loam, a standard section is a sensible starting point.

The public end of the drive has its own rules. The Larimer County Urban Area Street Standards, adopted by Fort Collins, Loveland and the county, require a permit before any access is built or rebuilt, concrete from the street edge to the right-of-way line, residential approach widths of 12 to 24 feet or 30 feet for a three-car garage, driveways on no more than half of a lot's frontage, and a grade no steeper than 8 percent within 20 feet of the gutter flowline. In the city, approach work needs a Sidewalk and Drive Approach Permit and a contractor holding the Right-of-Way Contractor License, and a dumpster or materials stored in the street need an encroachment permit.

Hot mix wants warm ground and warm air. Riley's Asphalt, a Colorado contractor, calls late spring to early fall the ideal paving season, and the campus station's median freeze-free window runs from May 1 to October 6, with 28-degree nights typically over by April 19 and back by October 17. After paving, SealMaster advises at least 30 to 60 days of cure before a first seal, and HomeGuide suggests about a year. A drive paved in August is usually first sealed the following summer, once the sealing season comes around again.

An overlay lays fresh asphalt on top of an old drive whose base is still sound; replacement strips everything down to the subgrade. Overlays make sense when the base is firm and the grade drains away from the garage, since the new layer raises the surface. Riley's Asphalt puts overlays at $2 to $4 per square foot and new drives at $3 to $10, most at $3 to $7. HomeGuide lists $5 to $12-plus per square foot installed, or $2,000 to $4,800 for a 400 square foot two-car drive, and Angi lists replacement at $8 to $15. The cost page sets them side by side.