Water is your driveway's biggest enemy

The Baltimore Sun

I need to build a gravel driveway. Is it going to hold up as a permanent driveway paving solution? What types of gravel are used for a driveway? Is it a build-it-yourself gravel driveway?

Properly designed and built, a gravel driveway can suit your needs for decades. And with some rented equipment you probably can do the job. Gravel driveways have to be maintained periodically, but the lower initial cost is often reason enough for most to deal with whatever needs to be done to keep the driveway in good shape over the years.

First, research basic road-building techniques. A long-lasting gravel driveway needs the same design characteristics one finds in a well-constructed major roadway. College textbooks on introductory civil engineering often cover this topic very well. You can also find great information on the Internet.

The soil under the gravel driveway must be well drained and strong, and free of any organic material such as sticks, tree roots, leaves or grass. All topsoil must be stripped off the driveway location. It is a very bad practice to build a driveway on top of spongy topsoil filled with organic debris.

Surface water can erode the gravel off the surface of the driveway, and subsurface water can turn strong subsoil into a quagmire. The weight of cars and trucks pressing down on the driveway can force water under the gravel, transporting silt from the subsoil into the gravel. As the silt squeezes between individual pieces of gravel, it causes the friction bonds between individual pieces of gravel to weaken. When this happens, your gravel driveway can fall apart in no time.

Installing a geotextile fabric on top of the subsoil before the first layer of gravel is installed can prevent the silt in the subsoil from fouling the gravel. The fabric comes in wide rolls and can easily be installed by two people.

The first layer of crushed gravel should be a larger-sized stone. Try to locate stones that are the size of baseballs or even softballs. Never use gravel that is rounded, because each piece can move easily when pressure is applied to it. Angular gravel interlocks with adjacent pieces.

Add additional layers of crushed rock in 4-inch thick layers, with each layer made up of smaller-sized stone. Compact each layer with a mechanical roller or tamping machine. The final layer of gravel should have pieces of angular stone no larger than a golf ball, with many of the stones being the size of marbles. If you can install 10 to 12 inches of gravel on top of the geotextile fabric, you should have a gravel driveway that will last for decades.

Expert home builder and remodeling contractor Tim Carter has 20 years of hands-on experience in the home industry. He is a licensed master plumber, master carpenter, master roof cutter and real estate broker. If you have a question, go to askthebuilder.com and click on "Ask Tim."

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