One layer or two layer installation? Which is best for you?
The asphalt on your driveway has seen better days. It is cracked and crumbling and the first impression of your home is not what it once was. You have noticed that the cracks go all the way down to the gravel below. It is time for a complete driveway replacement.
Calling three contractors to provide three quotes is the smart consumer move. However, now you are left with the difficult decision as to what recommended replacement option to go with.
Minimum building standards for the State of Michigan suggest that a driveway can be built on a 6-8 inch aggregate base and a 3” compacted surface of asphalt. There are two choices in general, a one layer installation process, and a two layer installation process.
Many residential contractors place a single 3” layer of asphalt down at one time and compact the asphalt with a one ton residential roller, resulting in a 2.5” driveway. The drawback to the customer is that this method can cause bird baths to form over time. That does not sound too bad until one forms right where you step out from your vehicle in the middle of winter and the bird bath has become a patch of ice. A single layer application process is less expensive for the contractor to perform and is less expensive for the home owner.
A two layer installation process consists of two distinct 2” layers of asphalt that are compacted to 1.5” each layer, resulting in a 3” driveway. Compaction is the name of the game in the longevity of a driveway. A rougher base course is applied and rolled to compaction prior to a finer finish course being applied as a second layer. This is a more time consuming process for the contractor and more asphalt tons are applied to the surface. A two layer method over an appropriate 6-8” base of aggregate ensures the absence of bird baths and other surface inconsistencies.
A two layer process costs the consumer about .50-.75 cents a square foot more compared to the one layer process. However, safety of your family, friends, and strangers is priceless. Spread out over the lifespan of 20-25 years of a driveway, the cost equates to just a few dollars per year.