Porous Driveway Materials
Drainable alternatives to asphalt divert rainwater runoff from overworked sewers—and look nicer
The Gravelpave2 paving system, about $3 per square foot; Invisible Structures.
Gravel and other porous materials are rarely the first choice for driveways, which is unfortunate as they have definite benefits over concrete or asphalt. Some of them last years longer, and most channel contaminants such as oil into the earth beneath the driveway, where microbes slowly break them down. Just excavate the old parking pad, put down a level base layer of gravel to help excess water filter down to the soil, and you're ready to install one of these:
When installed on top of the base layer, snap-together recycled plastic and polyethylene grids hold in place an additional 1 to 2 inches of decorative gravel in any color and last 25 years. Invisible Structure's Gravelpave2 (image 1, left) is about $3 per square foot; Alcoa's Geoweb costs about $5 a square foot.
Want to stick with a familiar look? Since it's made with little or no sand, the pervious version of concrete (image 2, left) has air pockets that permit drainage of 4 inches of water per minute. Installing the stuff requires special tamping and rolling. Beware: Pervious concrete can clog with dirt and other sediment, so be ready to run the leaf blower every so often.
Interlocking concrete pavers, such as those from Oldcastle Architectural are stronger and even more earthquake-resistant than a poured slab of concrete. In one weekend, you could have an attractive, patterned parking pad for about $2 to $5 a square foot.