How Thick Should an Asphalt Driveway Be?

Typical thickness

For a home driveway that carries cars and light trucks, a commonly used rule of thumb is 2 to 3 inches of compacted hot-mix asphalt on top of a compacted aggregate base of about 4 to 8 inches. Driveways that see delivery trucks, RVs or heavy equipment are often built thicker.

These are general rules of thumb, not a design. Local soil, drainage, frost depth and the vehicles using the drive all matter, and some towns specify minimums for driveway aprons. Ask your contractor and check local requirements.

The base matters as much as the asphalt

Asphalt is flexible. It spreads loads into the base, and the base spreads them into the soil. A thin layer of asphalt on a well-compacted, well-drained base often outperforms thick asphalt on soft ground. Signs of a weak base include alligator cracking, ruts and potholes that keep coming back.

• Remove topsoil and organic material; it never compacts properly.
• Build the base from crushed stone in layers, compacting each one.
• Shape the base to shed water away from the house and off the driveway.
• On clay or wet sites, a thicker base and sometimes a geotextile fabric are common fixes.

Work out base stone with the gravel calculator and see the gravel driveway guide for layering ideas.

How thickness changes the tons you buy

Compacted hot-mix asphalt typically weighs around 145 lb per cubic foot. That works out to about 6 tons per 1,000 sq ft for each inch of thickness, before waste.

tons = length × width × (thickness in ÷ 12) × 145 ÷ 2,000

Worked example

A single-car driveway 70 ft long and 10 ft wide, running back to a detached garage, is 700 sq ft. With 5 percent extra:

Going from 2 to 3 inches adds 50 percent more asphalt. When comparing quotes, make sure each one states the compacted thickness, not the loose depth, and the base depth. Try your own numbers in the asphalt calculator.

Typical driveway widths

Width multiplies straight into tonnage. A two-car driveway 20 ft wide and 50 ft long at 3 inches needs about 19.03 tons with 5 percent extra, or 17.26 tonnes. Local rules often limit driveway width at the curb.

One layer or two?

Thicker pavements are usually laid in more than one lift: a coarser binder course and a finer surface course. Each lift is rolled separately so it compacts fully. A single very thick lift is harder to compact well, which leaves voids that let water in.

Timing: plan in fall, pave when it is warm

Hot-mix must be placed and compacted while it is still hot. Cold air and cold ground make it cool too fast to compact properly, so paving is normally done in warm months, and many asphalt plants in cold regions close for the winter. Late fall and winter are a good time to get quotes, fix drainage problems and book a spring slot. A newly paved driveway also needs time to cure before sealcoating; ask your contractor how long to wait.

Asphalt or concrete?

Concrete driveways are commonly 4 to 6 inches thick for cars, with 5 inches or more where heavier vehicles use them, and they are priced by the cubic yard rather than the ton. If you are weighing the two, the concrete calculator and the concrete slab thickness guide help compare quantities.

Safety

Paving involves heavy rollers, trucks and material hot enough to burn. Keep people and pets clear of the work and off fresh asphalt until the contractor says it can be used. Call your local utility locating service before any digging or excavation for the base.

Frequently asked questions