Permeable Paving Solutions For Your Home
Across the United States, there are more than 2.7 million miles of paved surfaces. Roads, driveways, and parking lots use tremendous amounts of asphalt and concrete. Both of these materials are substantial contributors to the greenhouse gas emissions causing global climate change. Some estimates suggest that the cement industry might be responsible for up to 8 percent of total greenhouse gas emissions, with about 2.2 billion tons of carbon dioxide released in 2016 alone. Concrete, asphalt, and other impermeable surfaces also lead to stormwater contamination, the urban heat island effect, and erosion of urban and suburban landscapes. There might not be a viable alternative to concrete for our nation's interstate system. However, homeowners across the country can make a difference by opting for permeable pavement products for their driveways, sidewalks, and other hardscapes around their homes.
What is Permeable Paving?
Permeable pavers are products designed for vehicle and pedestrian pathways that enable the infiltration of precipitation into the surrounding soil. If you look out your front window during a massive rainstorm, you will probably notice an enormous amount of water rushing out of your gutters and downspouts and across your driveway. This stormwater takes the path of least resistance. This means that it usually either accumulates in areas around your home, causing erosion as it rushes across your soil, or rushes into the sewer system at the end of your driveway.
Is Stormwater Safe
Almost all stormwater is contaminated with several chemicals or potential pathogens, including:
- Pet waste
- Oil, gasoline, antifreeze, and other contaminants from vehicles that accumulate on roads
- Pesticides, chemical fertilizers, and other conventional lawn products
- Soaps and other cleaning products
- Heavy metals that leach from roofing materials
Improper stormwater management is one of the contributors to the contamination of bodies of water across the United States and the world. According to one recent analysis, around 13 percent of rivers in the United States, 18 percent of lakes, and 32 percent of estuaries are so polluted by excessive stormwater runoff that they are considered unsafe for swimming or fishing activities.
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Benefits of Permeable Paving Products
Reduce Runoff Effects with Permeable Paving
Permeable pavers are one way to drastically reduce the amount of stormwater runoff that occurs on driveways, sidewalks, outdoor patios, and other paved hardscapes around the home. Permeable pavers allow for the comfort and durability of a hard surface for both vehicle and pedestrian traffic while also permitting rainwater to infiltrate the soil instead of running off. The use of permeable pavers, then, can help reduce pressure on local sewer systems, avoid erosion in yards, stop lawn chemicals and contaminants from entering rivers and watersheds, and even replenish local aquifers.
Permeable Paving and Temperature Regulation
In urban areas, permeable pavers can play an essential role in reducing the urban heat island effect. In some densely populated urban areas (known all too appropriately as concrete jungles), the abundance of paved surfaces leads to higher temperatures than surrounding suburban and rural areas. In cities with populations over one million people, temperatures can be up to 5.4°F warmer during the day than surrounding areas. Permeable pavers that allow for vegetation can absorb some of that heat instead of reflecting it into the surrounding urban environment.
Permeable Paving Reduces Water Use
You won’t need to set up a sprinkler to keep your grass green. By incorporating spaced pavers, you cut down on the need for copious amounts of water during the summer heat. In addition, permeable pavers keep the natural water cycle intact. By directing water away from storm sewer systems and back into the groundwater table, the natural flow is preserved.
Permeable Paving for Home Certification
For homeowners looking to certify their house under the LEED for Homes rating system, opting for permeable pavers can also help you earn LEED credits for rainwater and heat island mitigation.
How Is Permeable Paving Different?
The main difference between conventional paving and permeable paving is that traditional concrete or asphalt is impervious, meaning that water does not infiltrate the surface. Conventional paving relies on fine aggregate like sand that permanently seals the surface to water. On the other hand, Permeable paving relies mainly on larger aggregate like gravel to maximize the material's porosity. In some cases, permeable paving also purposefully leaves space between the concrete pavers or tiles to allow for maximum water infiltration.
Permeable Paving Longevity vs. Concrete or Asphalt
These pavers last 25-30 years which is much longer than conventional concrete or asphalt – saving you time and money in the long run. Think big picture.
Are There Different Types of Permeable Paving?
Permeable paving might be as simple as choosing a gravel driveway instead of asphalt or concrete. Gravel or stone is a natural material, thus reducing the emissions associated with the manufacturing of concrete or other porous surfaces. Gravel driveways allow for a minimum amount of water infiltration while still keeping your driveway from becoming muddy or slippery. However, due to compaction over time, the level of water infiltration with gravel driveways or paths is minimal compared to the other permeable pavers we will review below. Also, gravel hardscapes can become extremely dusty during extended droughts and dry periods.
Pervious concrete, porous asphalt, and permeable interlocking concrete pavers are three of the most common options for permeable paving on the market today. Below, we briefly look at the pros and cons of these three common types of permeable pavers.
What Is Pervious Concrete ?
Pervious concrete is a select type of concrete with a high level of porosity, allowing water to infiltrate the surface, thus reducing the amount of stormwater runoff. Unlike traditional concrete, pervious concrete is made only with large aggregate material (gravel, for example). It uses minimal fine aggregate, such as sand. The more substantial aggregate material increases porosity while not compromising strength. On the surface, a concrete paste offers a durable surface for pedestrians or vehicles.
One of the main benefits of this type of permeable paver is that it requires no base layer. However, it should have a thickness of between 5 and 8 inches, which is significantly thicker than the other options we detail below. The seven-day cure time also increases the overall construction time frame and might increase installation costs. Pervious concrete costs between $3 and $4 per square foot and should last for between 20 and 30 years. However, there are concerns about freezing and thawing cycles in cold regions leading to premature cracking.
What Is Porous Asphalt?
Porous asphalt is similar to the bituminous pavement commonly used in roads and driveways. Like pervious concrete, however, the fine aggregate material is screened out during the manufacturing process. This essentially creates voids and extra space in the final asphalt product, thus encouraging water permeation. In numeric terms, the space in porous asphalt is about 16 percent. In comparison, conventional asphalt only has a void space of 2 to 3 percent.
A benefit of porous asphalt is that it can be laid in less thick installments, with a 3 to 4-inch layer over the top a gravel bedding being adequate for most driveways and walkways. Porous asphalts for home hardscapes can easily last up to 30 years and cure in only 24 hours. The price is generally lower, with an installed cost of around $2 per square foot. On the downside, porous asphalt products are usually only available in black or dark gray colors, which can increase the temperature around your home (and therefore worsen the urban heat island effect) by absorbing the heat from the sun.
What Are Permeable Interlocking Concrete Pavers ?
Permeable interlocking concrete pavers (PICP) are another permeable paver option for homeowners. These products are made by slid concrete paving blocks or strips that are separated by joints. These joints, or spaces, are subsequently filled with either gravel, small stones, or grasses to allow for water infiltration. Rainwater and stormwater permeate the soil through the joints between the pavers.
Depending on the application, PICP can offer a decorative touch to home landscaping. Traditional cobblestones can be used for a "Colonial-style" driveway instead of the conventional black asphalt. Allowing wider spaces between the interlocking concrete strips can allow for soil and grass to be grown, thus adding a touch of green to your driveways, back patio, or walkways.
PICP costs about $4 per square foot and has a lifespan of between 20 to 30 years. It requires a thickness of 3-4 inches with a 2-inch gravel base layer. The main downside to these products is that the joints can become clogged with sand or other fine aggregates, thus compromising water permeability. Periodic sweeping or vacuuming might be necessary to maintain optimum permeability levels.
What Are the Best Products on the Market Today?
There are dozens of permeable pavers on the market today. The best option for your particular needs will depend on your environment, your landscaping goals, and individual preferences. However, the following three permeable pavers are some of the best options on the market today.
PerkTop by Pervious Products
PerkTop can absorb over 200 inches of water per hour. It relies on very coarse sand aggregate along with Portland cement and other polymers. It can also achieve a compressive strength of over 2,500 psi, which is more than enough strength for private vehicles. This product can be installed for driveways, paths, sidewalks, and patios. Installation is also relatively easy and can be done by homeowners. Simply mix the 60-pound sack with 50 fluid ounces of water in a mortar mixer, and then apply over the base layer. PerkTop also comes in several colors to allow homeowners to improve the aesthetics of their landscape. PerkTop is not widely distributed outside California, but you can contact the company here to ask about shipping options.
GeoPave Permeable Gravel Pavers
GeoPave is a company that provides high-quality permeable gravel pavers. Their products rely on open-graded aggregate infill to maximize the level of water percolation into the subsoil. Unlike regular gravel, this product also relies on herringbone cells and an integrated mesh bottom to prevent the gravel aggregate from eroding or from releasing large amounts of dust during dry periods. The GeoPave permeable gravel pavers can be designed for virtually any type of residential project. You can get a free quote and find a nearby distributor here.
Belgard Permeable Interlocking Concrete Pavers
Belgard offers a wide variety of permeable interlocking concrete pavers that provide aesthetic quality to any home landscape while also improving water permeability. The company provides interlocking pavers specifically for outdoor patios along with other products used for driveways. Their turfstone pavers allow for naturally greenery to enhance your driveway and maximize water infiltration. You can contact a sales rep here to get a quote for your next permeable paver project.
How Should Permeable Paving Be Installed?
Homeowners can install any of the above-mentioned permeable paving products. However, for large projects such as a driveway or large back patio, hiring a certified professional might be necessary. Almost all permeable pavers require a base layer of gravel or crushed stone to be laid first. Pervious concrete products often come in pre-mixed bags. Renting a concrete mixer can allow for relatively easy mixing, though this does require heavy lifting. For permeable interlocking concrete pavers, it is best to hire a professional as they will be able to best layout the design for both aesthetics and maximization of water infiltration rates.
Can I Use Permeable Pavers in Cold Climates?
For those in colder climate zones, permeable pavers provide a particular benefit: since they reduce standing water, they also reduce the chance of ice forming. And with less ice, comes less salt. Your garden with thank you!
Disclaimer: This article does not constitute a product endorsement however Rise does reserve the right to recommend relevant products based on the articles content to provide a more comprehensive experience for the reader.Last Modified: 2021-07-09T16:51:32+0000Article by:
Tobias Roberts
Tobias runs an agroecology farm and a natural building collective in the mountains of El Salvador. He specializes in earthen construction methods and uses permaculture design methods to integrate structures into the sustainability of the landscape.