Exterior Worlds uses two types of permeable pavers for driveways. The first is actually a solid paver that is laid in an interlocking pattern with other pavers. The pavers are laid down in a special way, using special bonding materials that create a web of permeability that allows water to drain all the way through.
The second type of paver we use is made from pervious concrete. This type of cement is a specially mixed aggregate that features a porous constitution. While you may not be able to see them, the material is full of tiny holes and tube like channels that allow water to drain through the surface down to the bottom of the concrete.
Both types of driveways are constructed over a special foundation that is composed of fine, crushed stone. This layer is essential for the stability of the driveway. It is also essential to proper drainage of water, because its fine constitution actually traps water within its matrix much like a catch basin.
The water does not actually drain through this foundational layer, but rather seeps slowly into the ground. This allows natural processes to biodegrade any pollutants it carries.
Interlocking permeable pavers for driveways are typically not pervious themselves. Rather, they utilize the spaces between them to create a paved area that will effectively drain the majority of storm water downward into the ground before it cascades into the yard and out into the street. The spaces between the concrete pavers are filled with a mixture of sand or crushed stone.
In regard to cost, it is often much more fiscally wise for Houston landscaping clients to have a small driveway built of interlocking pavers with permeable spaces between. The sand and crushed stone mixture that holds the paver together is much stronger than mortar because it is flexible. It will not crack as mortar and concrete do, so it can better absorb the weight of multiple, heavy vehicles.
Interlocking permeable pavers for driveways work well for building small parking areas. Many homes in Houston have very small front yards, and much larger back yards. The cost effectiveness of building a permeable, interlocking paver surface is reasonable considering that the surface area is relatively small, and that the spaces between pavers provide more than adequate drainage.
Larger driveways, however, require maximum drainage to fulfill their purpose. Over 500 gallons of water can drain off of a 30 by 30 foot hardscape after a one inch rain. When this amount of water is striking the surface, we recommend investing in porous concrete permeable pavers for driveways. While they will of course cost more, they will better protect the surrounding plant life and street in front of the home from possible flooding.
An added benefit of using contiguously porous concrete is superior traction. With water immediately absorbed into the surface, people can get a better footing on the surface immediately after a hard rain has passed.
Also, porous permeable pavers for driveways can be fitted together in patterns that resemble stone or brick with no visible separation between them. This results in a more polished, clean aesthetic more apropos to many formal and contemporary Houston landscaping designs.