Is 2 inches of Asphalt Enough For a Driveway

Many homeowners and business owners sometimes face some dilemma when installing a new driveway or refinishing an existing one. You may have also heard or read in your research that an ideal thickness for an asphalt driveway is 2 inches, 6 inches, 9 inches, etc.

In some cases, you may encounter 2-3 different contractors with contrasting opinions about how thick an ideal asphalt driveway should be. 

Some consider the standard to be 2 inches thick, while others suggest up to 12 inches to be the best industry practice. The reality is, an asphalt driveway thickness is variable and specification dependent; it can be 2, 4, or even 9 inches thick; all have their significance. 

So, is 2 inches of asphalt enough for a driveway?

Let’s look at some variables/conditions that would reveal the perfect answer:

  1. The ultimate choice depends on the driveway’s particular use and the number of years you want it to last
  2. Usually, with a 2-inch asphalt driveway, residential properties will do just fine. Still, we highly suggest making your asphalt driveway at least 3-4 inches to have more value for your money.
  3. A busy lot or driveway would need 4 inches of compacted asphalt to hold up to all the depreciation it will encounter over the years.

The most important thing is discussing the project specification with a professional contracting company to ascertain what is perfect for your driveway.

The new asphalt over the gravel driveway

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Why asphalt thickness matters

What determines the thickness of asphalt pavement is whether the driveway would be used by light vehicles or heavy commercial vehicles. It all depends on the usage of the driveway. If the sub-base is not solid, and the asphalt thickness is not sufficient, the pavement can degenerate rapidly and require repairs. 

All you need to do is contact a professional paving contractor in your locality who understands the importance of asphalt thickness to prepare a solid sub-base for a long-lasting driveway.

You don’t have to just pick and use a particular thickness during installation because an asphalt pavement’s thickness greatly affects its long while performance. 

If you want to use the asphalt driveway for commercial purposes, which includes the passage of heavy vehicles, then the thickness of the parking lot would depend on the amount of traffic that the lot will witness.

When it comes to the thickness issue, it is vital to arm yourself with the appropriate information. If you don’t want sudden and unexpected degradation in your asphalt pavement, then proper thickness is needed. The thickness will significantly affect an asphalt pavement’s service life. The correct thickness will ensure you have the high-quality, durable, and long-lasting asphalt pavement that you need.

New asphalt on the road with leaves at the surface

The factors that affect how thick asphalt needs to be

You may sometimes question how thick the asphalt pavement should be when contemplating full-depth asphalt. Sadly, the question does not have a simple answer because some factors influence the thickness of an asphalt driveway or parking lot. Before deciding the acceptable thickness, there are many variables that asphalt paving contractors usually determine.

The factors that affect how thick asphalt needs to be for a perfect driveway or parking lots include:

  1. The Type of Soil
  2. Traffic Volume and Composition
  3. Layers of Asphalt

The type of soil

In asphalt thickness, data gathered about the soil plays a significant role. Subgrade material will most of the time be rock or soil, which needs to be thoroughly grasped before constructing pavement. 

If the soil is gravelly or sandy, it should compact correctly and offer good drainage. Conversely, it will be more challenging to achieve appropriate compaction if the soil is either clay, loamy or other soft types.

It is required that the soil provide a solid, stable base for the finished pavement.

To accomplish this, the engineers grade and compact the soil to create the subgrade. It may be important to remove and substitute some soil or use an aggregate subbase if your contractor can not obtain sufficient compaction.  The use of an aggregate subbase or the level to which the soil can be compacted can influence the asphalt depth required to provide the best outcomes.

Traffic volume and composition

How heavy the vehicles that will be using the pavement, the average number of cars that will use the pavement daily, and the frequency they will be traveling are all factors that need to be taken into account. 

Areas often used by trucks will need thicker pavement to withstand heavier vehicles. While the typical suburban driveway probably won’t need the same modifications. 

For instance, a residential driveway where about three to four cars will drive on at a low-speed per day does not have to be as dense as the pavement on a major highway carrying hundreds of articulated trucks and thousands of cars daily.

Layers of asphalt

There are various types of asphalt mix available, such as open-graded and conventional asphalt pavement. The asphalt pavement’s thickness can be affected by the size of the aggregates. 

For instance, the general rule is that each layer’s thickness must be at least three times higher than the aggregate’s nominal maximum size; a standard asphalt mix may be the lower layer, but the surface layer may use a thinner layer of a mix with smaller aggregates to provide extra aesthetic appeal without compromising strength. 

The asphalt driveway has a cracks

Consequences of not having a thick enough asphalt driveway

The thickness of an asphalt driveway or parking lot is the primary factor determining the structural capacity of a driveway. Suppose the thickness of an asphalt driveway is inappropriate. In that case, it will result in random cracking and, over time, leads to total degradation of the driveway, thereby defeating the durability you require from it. 

If you expect to use your parking lot or driveway for commercial purposes where large trucks will be driving on, a total of 4 inches thickness is needed to achieve that. Also, more thickness is required for a full heavy-duty commercial lot to provide the necessary durability. 

Suppose the asphalt driveway is not thick enough, and heavier vehicles like big trucks drive on it. In that case, the ultimate consequence is early deterioration, and it will defeat the purpose of constructing the driveway.

The red car leaks oil, and it flows into the parking lot.

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What causes asphalt driveway damages?

Apart from improper thickness of a driveway or parking lot, other things cause asphalt driveways to deteriorate quickly. There are:

  • Poor drainage
  • Lack of maintenance
  • Poor subgrade load-bearing ability

Poor drainage

Poor drainage causes damage to the asphalt driveway. To build a proper asphalt driveway, you need to carry out good drainage. There needs to be no humidity; ensure the water is drained away entirely before you can begin to pave.

Lack of maintenance

It is common for asphalt pavement to crack as it ages due to continuous exposure and weather patterns. Fortunately, you can detect and fix several cracks with a yearly checkup. Pavement seal coating and crack sealing are a good maintenance practice to prevent water damage.

Poor subgrade load-bearing ability

It is commonly reported that inadequate subgrade results in pavement damage. This happens when the soils below the asphalt base layer are clay-based rather than stone-based. If you observe ruts appearing in your parking lot or driveway after a round of rain, it could be a sign that the subgrade is unable to support the weight.

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The thickness of an asphalt driveway plays a critical role in its longevity. The purpose of designing a driveway is also to determine how thick it should be. What is essential is to hire a professional contracting company and discuss your project specification to determine what is perfect for your driveway.