When it comes to building strong, long-lasting asphalt driveways and carparks in Sydney and across NSW, proper base preparation is the key to asphalt longevity. A well-prepared base ensures the asphalt layer remains durable, stable, and resistant to cracking or rutting. Without the right groundwork, even the thickest asphalt surface can fail prematurely.

What Does Base Preparation Mean?

Base preparation is the process of ensuring the ground beneath the asphalt is stable, compacted, and capable of carrying expected loads. According to NSW asphalt standards (based on Austroads and RMS specifications), a quality base typically includes:

• Removal of soft or unstable material

• Placement of a crushed rock or road base layer

• Proper compaction using rollers

• Grading for correct water drainage

• Testing for strength and density

This foundation allows asphalt to perform as intended for both residential driveways and commercial carparks.

Why Proper Base Preparation is the Key to Asphalt Longevity

1. Prevents Cracking and Potholes

Poor base preparation is one of the leading causes of cracks and potholes. If the base is uneven or poorly compacted, the asphalt above will shift and break under stress.

2. Handles Heavy Vehicle Loads

For driveways and especially carparks that see delivery trucks or service vehicles, the NSW asphalt standard thickness usually requires:

• Residential driveways: asphalt 30–40mm thick on a compacted base

• Commercial areas / truck access: asphalt 40–50mm thick or more depending on load

Without a properly prepared base, these thicknesses won’t matter — the asphalt will still fail under pressure.

3. Ensures Proper Drainage

Water is asphalt’s worst enemy. A well-prepared base is graded to allow water to run off instead of pooling under the surface, which can quickly erode the subgrade and shorten pavement life.

4. Maximises Longevity and Reduces Costs

A strong base ensures the asphalt surface lasts 15–20 years or more with regular maintenance. Cutting corners in preparation often means costly repairs or even full replacement within just a few years.

How Base Preparation is Done

Step 1: Site Inspection

Our estimators assess the soil, slope, and existing surface conditions.

Step 2: Excavation and Removal

Unstable material and debris are removed, and the site is levelled.

Step 3: Road Base Placement

A layer of crushed rock or gravel (usually 100–150mm, subject to ground conditions) is spread.

Step 4: Compaction and Testing

Heavy rollers compact the base to meet NSW density standards.

Step 5: Final Grading

The base is shaped to ensure water drainage before asphalt is applied.

Frequently Asked Questions

Does asphalt need a base?

Yes. Without a solid, compacted base, asphalt will quickly crack, rut, or sink. The base is what gives the asphalt its strength and durability.

How thick should asphalt be

According to NSW asphalt standards:

• Residential driveways: 30–40mm asphalt layer on a compacted base

• Commercial carparks / heavy traffic areas: 40–50mm or more, depending on load and conditions

Can I lay asphalt over concrete without base preparation?

It’s possible, but not always recommended. Cracks in the underlying concrete can reflect through the new asphalt. In most cases, repairing or replacing the base first ensures better longevity.

How long does asphalt last with proper base preparation?

With correct base preparation and regular maintenance, asphalt driveways and carparks can last 15–20 years or more. Poor base work can cut this lifespan in half.

What happens if the base isn’t prepared properly?

An improperly prepared base leads to uneven settling, water pooling, cracking, potholes, and early failure of the asphalt surface.

Final Thoughts

At Spencer Asphalting, we know that proper base preparation is the key to asphalt longevity. Whether it’s a new residential driveway or a large commercial carpark, taking the time to build a solid foundation ensures your investment will last.

Every site is different, and base requirements depend on soil type, drainage, and traffic conditions. That’s why we recommend having one of our expert estimators assess your location before starting.