Though the name "tar-and-chip" might not be familiar, you almost certainly have seen driveways and roads built this way. Or maybe you know it by one of its other names: chip-and-seal, seal chip, macadam, or liquid-asphalt-and-stone. Whatever the name, it may not be the first thing that comes to mind when you think driveway, considering that concrete, gravel, pavers, and asphalt are all more common paving choices.
You've almost certainly driven over miles of tar and chip roadways and parking lots, and this form of paving has a long history of successful use, especially in rural areas. And it's a good driveway choice for those wanting to keep costs down.
Building a tar-and-chip driveway is a pretty simple process. First, as with most driveway materials, a gravel base is installed. Then, hot liquid asphalt is poured over the gravel. This is followed by a coating of loose stones, which are rolled into the asphalt to form the finished surface. It's in the selection of this top layer of stones where you have choices to make regarding the look of your finished driveway. You can choose from different colors of stones to create a unique and personally appealing surface.
Tar-and-chip can be installed over existing driveway materials, provided they are in reasonably good shape.
Understanding the Terms
Many people believe the terms to be interchangeable, but the terms "tar," "bitumen," and "asphalt" have slightly different meanings. Tar is a liquid or semi-liquid substance distilled from an organic material high in fluorocarbons. Tar can be derived from pine, coal, peat, or petroleum, among other substances.
"Bitumen" and "liquid asphalt" are synonymous terms. Both refer to a sticky liquid or semi-liquid form of petroleum. Unlike tar, which is a distilled substance, bitumen/asphalt is a naturally occurring material.
When the term "asphalt" is used to describe hard paving, it refers to a mixture of liquid asphalt (bitumen) and aggregate that is laid to form a paved surface.
Today, most tar-and-chip paving does not use genuine tar but is instead comprised of liquid asphalt (bitumen).
Tar-and-chip differs from asphalt paving because the petroleum-based liquid and aggregate are applied in separate layers; asphalt, on the other hand, is a premixed blend of bitumen and gravel, which is applied as a hot, malleable material that is packed and flattened to form a paving surface.
Advantages of Tar-and-Chip Driveways
- Low cost: Tar-and-chip driveways cost considerably less than traditional asphalt.
- Rough surface: The texture of tar-and-chip paving makes for better traction when the surface is wet or snow-covered. Both asphalt and concrete are more slippery than tar-and-chip.
- More solid than gravel: While gravel makes for an even cheaper driveway surface, tar-and-chip creates a harder, more durable surface. Tar-and-chip paving can last as long as 10 years.
- Low maintenance: Little upkeep is required with tar-and-chip driveways. Unlike asphalt, it doesn't need to be repeatedly sealed, and small cracks tend to heal themselves.
Disadvantages of Tar-and-Chip Paving
- Limited lifespan: Seven to 10 years is the average lifespan of a tar-and-chip driveway. At this point, you should expect to apply another layer. By contrast, concrete can last as much as 40 years.
- Can be damaged by snowplows: The rough surface of tar-and-chip paving can be scraped by snowplows that apply too much pressure. If using a plow, keep the blade slightly above the surface; a shovel or snow blower might be a better choice.
- Contractors can be hard to find: Unlike asphalt paving, which is so common that installation contractors are plentiful, you may have trouble finding a firm skilled in the installation of tar-and-chip driveways. And this is not a DIY-friendly project. Before getting too committed to using tar-and-chip on your own driveway, do some online hunting to see if you can find someone in your area with the necessary experience and equipment.
Since it is primarily composed of asphalt and gravel, it is useful to compare the cost of a tar-and-chip surface to those other two options.
A tar-and-chip driveway will typically cost about twice as much as a gravel driveway and a little less than an asphalt driveway. Expect to pay in the range of $2 to $5 per square foot (the exact cost will vary depending on your region and the labor costs in your community). As is the case with asphalt driveways, the costs of oil are a big factor in the installation expense. The cost of these driveways will likely climb a bit when the commodity price of oil increases.