Driveways, Walkways

Published on April 17th, 2013 | by Henri


Asphalt driveway keeps sinking and cracking

Q.    My driveway was initially installed when my home was built in 1976. It is approximately 20 x 100 feet with a downhill grade (30%) from the house to the street. The original driveway had approximately 4 inches of sand and gravel for a foundation, topped by what I was told is 4 inches of asphalt. I routinely sealed it in the fall with a polymer/asphalt sealer. Year by year it sank and cracked.

About ten years ago I had a contractor lay two inches of asphalt on top of the existing driveway. This was fine for a few years, then the sinking and cracking began again. I plan to have it re-topped again with another two inches of asphalt. Most of the contractors that I have contacted for estimates, recommend digging up the entire driveway, hauling it off in dumpsters, and starting from scratch with a new foundation, etc. The difference in cost is $2,500 for a 2-inch topping versus $20,000 for a new installation. What do you recommend?

A.    It sounds like the driveway needs a more stable base. Going with another 2-inch topping will get the same results as the last time. It will be fine for a few years, but will start sinking and cracking again soon.

If you are planning on staying in your home, investing in the removal and replacement of your old driveway would be sound. However, the $20,000 price for this sounds high, but could be justified if the contractors are going to dig down and install more gravel this time – like at least 1-foot or more. They should also install a geotextile fabric on the original soil before putting down the gravel to prevent it from sinking. If you haven’t already done so, you may want to get several estimates.

The alternative is to top the asphalt every few years as needed. If you divide $2,500 into $20,000 and the topping lasts five years, you can put eight toppings on (discounting rising prices); that’s 40 years!
Keep in mind that asphalt is not a structural material unless it is applied very thick. The asphalt on most driveways is really the “roof” used to keep the sub-base materials (gravel) dry and compacted. If those sub-base gravels are not deep enough or they become wet, it will add to the sinking and cracking that you are referring to.

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