Daniel Bortz, Special to The Washington Post
Whether you're repaving your driveway or building one from scratch, selecting the right material is crucial. There are a handful of options to choose from, though, and each has its pros and cons with respect to price, durability, aesthetics and eco-friendliness.
Here's what you need to know about the most common materials.
Life span: 25 to 50 years
Concrete is tops when it comes to durability and versatility. Composed of various types of stone aggregate held together by water and a lime-based binder, concrete provides a smooth, stable and secure foundation that holds up well in any climate and requires little to no maintenance, says Allison Bean, editorial director at home improvement website TheSpruce.com.
"Not only does the material readily move water, concrete also stays relatively cool when exposed to direct sunlight," says Hunter Macfarlane, a project expert at Lowe's, and "its simple look can be updated with paint, or it can be stamped to offer a unique appearance."
In addition to being relatively expensive, concrete is "not the most attractive building material," Bean says.
Concrete is intended to be a solid surface that nothing can penetrate - including water, Macfarlane says. Large impermeable surfaces can send excess rainwater into sewer systems and waterways instead of into the ground, taxing and polluting water systems. "On the whole, concrete is one of the least environmentally friendly choices for a driveway or hardscape," Jean-Paul LaCount, founder and editor of the Chic Ecologist, a green-living news and information website, said in an email. "Concrete consists mostly of cement, which when created, is one of the largest contributors to carbon dioxide emissions (CO2), along with significant volatile organic compound (VOC) emissions."
The good news:
"Consumers can choose 'low-carbon' concrete mixes, and they are now more readily available than ever," says Wes Sullens, codes technical development director at the U.S. Green Building Council. You can also find a concrete supplier that uses recycled aggregate - "essentially using ground-up concrete as a replacement for raw gravel in concrete," Sullens says.
Life span: Up to 100 years (depending on winter-weather conditions)
Gravel is a great option for the budget-conscious, especially people with longer driveways, Bean says. Another selling point: "Gravel compacts much better than plain rocks," creating a more stable surface that sheds water easily, Bean says.
Most gravel driveways need to be regraded every year or two, depending on how much traffic passes through, Bean says, adding that gravel driveways tend to hold up better in warmer climes. "Your driveway will be more difficult to plough or clear with a snowblower since the mixture of rocks, sand and clay can cling to ice and snow much better than other materials," she says. "At the end of a long winter, you may find you need to replace a good amount of your gravel."
"Having the second-lowest impact out of the bunch, gravel can be sourced locally and provides a porous surface for [rainwater] absorption," LaCount says.
To minimise the environmental impact, Sullens recommends using recycled gravel. "Often, recycling centres will crush old concrete into sizes suitable for use in driveway base materials, or even the final gravel layer," he says.
Concrete is tops when it comes to durability and versatility, but it's not very eco-friendly. David Beaulieu/The Spruce
Life span: 12 to 20 years
Mainly composed of rock, sand and asphalt cement, asphalt has a number of attractive qualities as a driveway material. When properly installed, an asphalt driveway "will feel and act much like concrete but is much cheaper," Bean says. Also, because asphalt is a petroleum product, similar to tar, it's flexible and less likely to crack under the elements, according to Bean.
Though extremely durable, asphalt driveways have to be sealed every few years, Bean says, and can get very hot during the summer.
"Asphalt is probably the least environmentally friendly out of the bunch," LaCount says. "Consisting of oil and other petroleum by-products combined with stone particles, I probably don't need to explain how both the drilling, processing and application of oil products are harmful to our environment."
Using recycled asphalt, or cold-mixed asphalt that does not require the excessive heat to install, can help reduce an asphalt driveway's negative impact on the environment, Sullens says.
Though some asphalt can be considered "porous," Bean says, it doesn't allow rainwater to reach the water table below.
Life span: Up to 100 years
Capable of lasting up to a century when laid properly, paving-stone driveways "have a lot of character, making them a great option for added curb appeal," Bean says. Made of tough granite, flagstone or other stone, pavers require little maintenance and prevent water from pooling. Live in an area with heavy snowfall? A heating system can be installed beneath the pavers to keep snow from accumulating, says Joe Raboine, director of residential hardscapes at Belgard, a national landscape design and products provider.
Paving stones are expensive, and installing them is labour intensive, so you'll have to shell out a good chunk of cash to use this driveway material.
Paving stones, sourced from quarries around the world, can be relatively eco-friendly. You'll want to use local stones that are harvested nearby, if possible, and ensure the provider followed environmental protections during extraction. When installing, consider using sand or small rocks between stones, rather than a cement-based filler. This will improve permeability, allowing more rainwater to soak into the ground, rather than running off.
Life span: About 25 years
A standard building material for driveways, clay brick easily stands up to normal usage and moderate weather, Bean says. Also, when properly installed, brick provides a noticeably smooth surface.
Brick driveways require regular maintenance. They must be pressure-washed twice a year, Bean says, and the bricks should be resealed after each washing to prevent the clay from flaking or peeling.
"Often confused as an environmentally friendly building material, most bricks today are made from mined clay heated in energy-intensive kilns," LaCount said. "Bricks laid with mortar or other impervious filler will have the same runoff issues as concrete and asphalt, so gapping with sand or dirt would be a way to increase the eco-factor of this material."
As always, Sullens says, using recycled materials is best for the environment.
One to five years, depending on weather and your preferred aesthetic. "The more you drive on the surface, the more the shells break and compact, so if you like the look of larger shell pieces, you may want to replenish the driveway from time to time," Bean says. Also, seashell driveways in areas with heavy wind, erosion or water activity - where shells can get damaged, covered in sand or washed away - may need to be replenished more often, Bean says.
Though it's a popular option primarily for homes located on the coastline, seashell driveways "have an allure that could make even the most landlocked driveway look serene and beachy," Bean says. The shells - typically a combination from clams, oysters and scallops - break into smaller pieces over time, creating a well-dispersed, stable surface. Seashell driveways are also eco-friendly because they recycle waste from the seafood industry, Bean says.
Because seashells aren't readily available in all areas, installing a seashell driveway can be expensive. Also, "speaking from traumatic childhood experience, you might end up cutting up or hurting your feet if you try to walk on one of these driveways barefoot," Bean warns. Like gravel, shell driveways can be difficult for snow and ice removal.
"From an eco-perspective, these are the best," says Sheridan Foster, founder of Elemental Green, a green home-building and renovation resource. "There are no toxins in the shells. They are made of a renewable resource that is a waste product from the food industry. Seashells degrade and form soil over time, so end of life is taken care of."
But the sourcing of the seashells is important, Sullens says. "Are they coming from far away? Were the seashells harvested legally and following best practices? Ask these questions of the suppliers."