If you’ve noticed your new asphalt driveway starting to dip or sink just months after installation, you’re not alone—and you’re right to be concerned.

Across Manchester, NH, especially in neighborhoods like Rimmon Heights and North End, this issue is more common than you’d think.

Homeowners from Goffstown Road to Hanover Street often call us wondering why their smooth new surface is already forming low spots.

Let’s get into what’s really going on—and what you can do about it.

Key Takeaways

• Most new driveways in Manchester sink because contractors skip crucial steps like soil testing and base compaction.
• Loose clay soil and steep slopes in areas like Hackett Hill cause fast erosion and uneven driveway settling.
• A weak base layer without proper gravel depth or compaction leads to sinking under cars and heavy rain.
• Poor drainage in places like Bakersville allows water to pool under asphalt, washing out the base and causing dips.
• Parking heavy vehicles too soon or paving over tree roots can trigger sudden settling months after installation.

Soft or Unstable Soil Beneath the Surface

In many parts of Manchester—especially near the Merrimack River basin or older areas around Bridge Street—the soil is loose or high in clay content.

If this base soil isn’t compacted correctly before paving, the weight of vehicles, rainwater, or melting snow can cause the asphalt to settle unevenly.

If you live near steep terrain like Hackett Hill or Wellington Road, slope-related drainage issues can worsen erosion, making soil instability even more problematic.

Inadequate or Incorrect Base Layer

A strong asphalt driveway starts with what’s underneath. In Manchester, that means 4–8 inches of well-compacted crushed stone or gravel. If a contractor skimps on materials or fails to compact them in layers, small voids form—and those voids eventually collapse under pressure.

This issue is especially common in fast-track developments around South Manchester and Candia Road, where speed can come at the cost of long-term quality.

Water Drainage Problems

With an average of 45 inches of snow annually, Manchester’s meltwater has to go somewhere. If your driveway lacks proper slope for drainage channels, water can seep below the surface and erode the base.

Low-lying neighborhoods like Bakersville or the Sweeney Park area are particularly prone to standing water. Poor grading, clogged gutters, and missing perimeter drains all contribute to premature sinking, soft spots, or cracks.

Heavy Vehicle Traffic Before Full Curing

New asphalt needs time to cure—typically 24 to 72 hours to dry completely before light use and up to a month before it’s ready for heavy vehicles. Parking an RV, work truck, or trailer too soon can compress weak spots in the asphalt before it fully sets.

This problem often shows up in tighter neighborhoods like Weston Road or Calef Road, where homeowners rely on the driveway for overflow parking.

Tree Roots or Organic Material Left Underneath

In wooded lots and older neighborhoods like Highland Park or Green Acres, buried roots or old stumps under the driveway may decompose slowly over time. As they rot, they leave air pockets beneath the asphalt, eventually causing visible dips or soft spots—sometimes months or even years after paving.

Even if the topsoil was cleared, any remaining organic matter beneath the surface can eventually destabilize the asphalt above.

Seasonal Frost Heave and Freeze-Thaw Cycles

If you’ve lived in Manchester through winter, you’re familiar with the brutal freeze-thaw swings. Moisture under the asphalt freezes, expands, then contracts as it melts—causing upward and downward shifts in the base.

This is a recurring issue in hilltop neighborhoods like Mount Saint Mary, where sunny exposure and snow buildup combine to stress the asphalt from both above and below.

The Bottom Line: It’s All About Preparation

No matter how smooth your asphalt looks on day one, it’s only as strong as the ground beneath it. In Manchester, where clay-heavy soils, slope, and wild weather collide, poor base prep is the leading cause of premature sinking.

If your driveway is already sinking, it’s time to bring in professionals who can correct grading issues, perform proper soil testing, and rebuild with the right gravel depth to prevent costly repairs later.

Why Acting Early Saves You in the Long Run

What looks like a minor dip today can quickly become a major issue, leading to pooling water, widening cracks, and even complete replacement. The earlier you catch the signs, the more affordable and effective your repair options will be.

But the best long-term solution? Working with a highly-rated contractor who builds it right from the ground up.

Let’s Get Your Driveway Done Right

If you’re already dealing with a sinking driveway, we get how frustrating that is, especially after investing good money expecting it to last.

At American Asphalt Paving, we’ve helped homeowners all over Manchester—from the West Side to the Valley Street corridor—get durable, weather-resistant results.

We specialize in asphalt driveway installation that holds up through harsh New Hampshire winters. Our approach includes expert grading, soil stabilization, and layered base prep to match the conditions of each neighborhood.

Ready to stop sinking and start paving?

Contact us and request your on-site estimate today, and let’s make your driveway a solid investment from the start.