Overlay or Full-Depth Hot-Mix Asphalt Paving

Did you know that you can overlay hot-mix asphalt over your existing driveway?

Read on, though, to find out why full-depth is preferable to the overlay method.

Overlay Asphalt Paving

If you have an existing asphalt or concrete driveway, but it’s in poor repair, you can overlay another layer of asphalt paving on top.

Still, the existing surface needs to be in a minimally good condition to support the new asphalt paving. If more than 75% of the existing driveway is cracked, you’re better off pulling off the driveway and starting anew.

The asphalt contractor will first patch minor holes and cracks with hot mix. Then a surface of up to 2 inches of hot mix will be laid on top of the patched driveway.

Full-Depth Asphalt Paving

Full-depth is the better option. There are two ways to define full-depth asphalt paving.

Actual Full-Depth.

Nothing between the hot-mix and the soil. Four to six inches of hot-mix asphalt laid directly on soil. This is the most preferable type of full-depth paving.

Full-Depth With Partial Aggregate Replacement

Three inches of compacted aggregate base is equal to one inch of hot-mix asphalt paving. A typical arrangement is to lay down 6-8 inches of compacted aggregate under 3 inches of hot-mix asphalt paving.

Benefits of Installing Asphalt Rather Than Concrete

Homeowners may have a hard time deciding to install asphalt paving or concrete. This list of asphalt paving benefits should help make the decision easier!

  • Asphalt paving is more flexible–and therefore less prone to cracking–than concrete.
  • Asphalt paving is done by the hot-mix method and therefore sets faster than concrete, which needs to dry.
  • Asphalt paving is unaffected by the application of rock salt or ice melt during winter months.
  • Asphalt paving is generally cheaper than concrete paving.
  • Asphalt paving does not need the installation of rebar forms. It can even be installed over an existing driveway.
  • Asphalt paving is a competitive business, so it is possible to find good deals.

Asphalt Paving Timetable

Looking for a Window of Opportunity to Install Driveway Asphalt?

We can help.  Homeowners often ask asphalt contractors if there is a best time of year to lay down asphalt.  Yes there is.  All other factors being equal (that is, the temperature of the delivered asphalt being 300 degrees F and final temperature 174 F), there are certain standards for when and how long it takes to install driveway asphalt.

The rule of thumb is that the colder the temperature and the lesser the depth of asphalt, the less time the contractor has to work with it.  The best window of opportunity is shown in blue in the table; the cautionary time in yellow; and the unrecommended time in red.

What’s the Temperature Like?

(Degrees F – Surface and Air)

How Long Does the Contractor Have to Work with the Asphalt? (Minutes)

1.5″ Depth of Asphalt

2″ Depth of Asphalt

3″ Depth of Asphalt

40 º

16

25

46

50 º

17

27

50

60 º

19

30

55

70 º

21

33

60

80 º

24

37

67

Source:  National Asphalt Paving Association

Asphalt Paving Season

Is There a Best Time to Install Driveway Asphalt? Yes.  Read on…

You’ve seen highway road crews laying down asphalt in the worst of conditions. So you might think: how hard can it be to lay down asphalt on my driveway?

Hot-mix asphalt is finicky and its installation depends mainly on the temperature of the air and of the surface. The National Asphalt Pavement Association recommends that contractors stay away from laying down “low lifts” of asphalt in very cold temperatures. A “low lift” is basically the height of the layer of asphalt. A low lift is 1.5 inches; a high lift is 3 inches.

Remember that depth does matter in the case of laying down overlay versus full-depth asphalt paving.

The worst-case scenario would be a low lift of 1.5 inches laid in 40 degrees F. Asphalt workers need time to manipulate the hot-but-cooling-rapidly asphalt mixture. Think of when you spread out hot food on your plate to cool it down. Spreading a thin layer of, say, mashed potatoes hastens the cooling process. But cooling, while good for food, is fatal for hot-mix asphalt.

The same 1.5 inches of hot-mix asphalt is still a dicey proposition up to 60 degrees F. Only above 60 degrees does this 1.5 inch lift become workable.

See our chart showing the “window of opportunity” for laying hot-mix asphalt.

Now let’s double the lift from 1.5 inches to 3 inches. The 3 inch lift is perfectly capable of being worked at 40 degrees F. It’s not the best temperature, but it can be done. The paving crew has a full 46 minutes to work with this higher lift, as opposed to only 16 minutes with the lower lift at the same temperature.

And 16 minutes is such a short time to work the asphalt that most contractors will refuse to take on such a job. If it’s too cold for asphalt and you’re desperate, consider laying a concrete driveway.

Asphalt Paving Resources

Unlike a lot of home renovation topics, it’s tough for homeowners to find much information about asphalt paving.  The field is littered with asphalt paving companies and industry groupd, and really nothing for the consumer.  We try our best for you here:

NHMPA

The National Hot Mix Pavement Association (NHMPA) is right there on top of your search engine results, but that doesn’t mean a thing if you’re a homeowner.  It’s an industry group and doesn’t really have much for the consumer.  Still, it’s there if you need it.

But NHMPA does have a couple of consumer-related resources.

Beyond Roads

A group called Beyond Roads provides information about asphalt paving itself, but not necessarily about consumer-driven asphalt products.  So it’s a fairly interesting high-level resource, it won’t help you find a contractor in your area.

Install Asphalt Paving – FAQs

Learn a few basics about residential asphalt paving:

Q:  Can I use a driveway sealer like MasterSeal instead of the more expensive option of an entire new hot-mix asphalt driveway?

Yes, you certainly can–if your driveway is in good enough shape. Driveway sealers are only a surface treatment, though–a way to extend the life of your driveway. It’s the driveway equivalent of painting your house.

Q: What about crack sealing instead of using driveway sealer?

Crack sealing is a more effective type of patch than driveway sealing alone. You’ve seen this before on roadways: this thick, caulk-like substance injected in cracks. Crack sealing can definitely extend the life of your driveway more than driveway sealant, but not as well as an entirely new hot-mix asphalt paved driveway.

Q: I’ve decided that my asphalt driveway is in such bad shape that I can’t use driveway sealer. What’s the cheapest way to install real hot-mix asphalt?

Yes, you don’t need to rip out your existing driveway. If your existing driveway is in decent enough condition to provide a solid base, you can use the overlay asphalt installation method.

Q: Does weather affect when I can install asphalt paving?

Yes. Warmer temperatures give the contractor more time to work with the asphalt before it hardens. For 1 1/2″ of asphalt paving, temperatures should be at least 70 degrees Fahrenheit. Two inches of asphalt paving give you a wider range of temperatures to work with–40 degrees is the minimum. Wind conditions will decrease the amount of time the contractor has to work with the asphalt. If there is too much moisture, paving may be delayed until conditions are dry.