How Thick Should a Commercial Asphalt Parking Lot Be?

Southern California roads and parking lots are paved predominantly with asphalt. However, not all paved surfaces require the same thickness of asphalt.

A typical asphalt parking lot consists of three crucial structural elements: a subgrade, asphalt thickness, and a drainage system. You should use expert contractors to ensure the proper layering of each compaction and the right thickness of asphalt on the commercial parking lot.

Creating designs for a parking lot's thickness depends on the condition and the soil quality of the subgrade and the traffic type, as well as the conditions of the business. However, most commercial owners and paving contractors often overlook essential elements of a parking lot, asphalt thickness, hence the constant need for regular maintenance and repairs.

Asphalt Thickness

What Happens if Your Commercial Asphalt Parking Lot is Too Thin?

The base layer below the surface course helps support the weight of traffic vehicles on the parking lot. Proper asphalt thickness helps spread and even out this weight for better balance and functionality. However, parking lots with thin asphalts do not distribute the weight appropriately and instead compress all of it under the tire. This lack of even distribution causes the immediate surface to develop cracks due to too much weight.

Without proper maintenance and repair services, the fatigue cracks extend and grow larger, causing the parking lot's surface to break down sooner than expected.

So How Thick Should the Asphalt in a Commercial Parking Lot Be?

The parking lot's functionality, reliability, and durability correlate to the thickness of the subgrade course and the paved surface course. As already mentioned, the exact calculation of what level of thickness is best will depend on the subgrade soil quality and the type of traffic your facility expects. For instance, heavy trucks weigh more on asphalt parking lots than small cars.

Some contractors will choose to layer the surface with aggregate and asphalt or solely opt for a full-depth asphalt layer after the subgrade compaction. Either way, the parking lot's surface must be created on top of a solid, reliable, and supportive subgrade with excellent condition.

Commercial Asphalt Parking Lot Thickness

  • A light-duty parking lot's surface course with full-depth asphalt, on top of an excellent subgrade layer, needs to be at least 4 inches thick.
  • For a parking lot traffic with heavy-duty vehicles such as loading dock, trucks, or roadways, the asphalt should be between 10 to 12 inches thick for a poor subgrade and about 6 inches for an excellent subgrade.

Heavy Duty vs Light Duty Commercial Parking Lots

  • A full-depth asphalt light-duty commercial parking lot will need a layer about 4 inches thick of asphalt on a solid and practical subgrade.
  • For a heavy-duty commercial parking lot going with a full-depth asphalt layer, applying about 6 to 7.5 inches thick of the asphalt layer on a fine subgrade is best.
  • For a light-duty commercial parking lot with a base made of aggregate, you should apply a 3-inch thick asphalt layer on top of a 6 inches aggregate base.
  • A heavy-duty commercial parking lot with a base made of aggregate will need a layer of  6 inches thick asphalt mix on top of a 3-inch layer of aggregate base.

Generally, a commercial parking lot designed with both aggregate base and hot-mix asphalt, it is recommended that you apply a total thickness of at least 9 inches. Calculate the ratio of aggregate to asphalt depending on the amount and type of traffic your business expects.

For the best experience, use thicker base and asphalt layers for substantial, heavy traffic to create a firm surface course that can support a heavy roller truck driving over it without leaving tracks. In addition, some parking lot areas with frequent traffic, such as the entry and exit points, may need greater asphalt thickness than others.

Why is a Commercial Asphalt Parking Lot Thickness Critical?

Your parking lot is the first thing your customers or clients see when they arrive at your business property. It serves as a welcome sign and represents your company's brand, appearance, and the level of services you offer customers.

A clean, robust, and well-maintained parking lot gives a good impression of your business and communicates how established and up-to-date your business is. This improves your brand's reputation and gains more clients for the company.

A thick asphalt parking lot with good maintenance not only provides a positive first impression to customers but also ensures the safety and functionality of clients and customers accessing the property. When a parking lot has a poor paved surface with improper thickness, it soon develops potholes, cracks, and depressions. These can increase the chances of accidents, leading to low business and even lawsuits.

Lastly, a commercial asphalt parking lot with improper thickness cannot endure the weight of light and heavy-duty vehicles parked on it. The weight results in breakdowns and damage to the surface soon after installation or repair, when generally, a good asphalt surface should last up to 20 years or more.

Therefore, you should invest in suitable asphalt materials and skilled contractors to ensure a positive customer experience and secure traffic. Skimping on your commercial parking lot thickness will result in poor business reputation and increased recurring maintenance costs.


Give the parking lot similar attention and considerations as the business building. It is generally the first and the last impression and experiences your clients will have of your facility. And while many business owners overlook it, the condition of the commercial parking lot can make or break the flow and functionality of the business.

The quantity and material of the asphalt you use in the parking lot should meet the correct specifications for proper thickness. Empire Parking Lot Services experts understand and know what it takes to design and keep your lot intact, even in unfavorable weather conditions. Contact us at 714-633-0300 to have our experienced team assist you with your next asphalt parking lot maintenance project.

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