Permeable concrete walkways are replacing asphalt as national and state parks because they help protect the watershed.
Now they're an option for homeowners as well.
Better still, they come in a variety of shapes and colors and cost about the same as traditional concrete blocks.
One such offering is SubTerra Stone, a permeable paver that looks like natural chiseled stone.
The false joint structure in the modular squares allows water to drain through to the sand substrate below. Real joints between the paver squares are filled in with a special sand blended with polymers and cement. The end result is a walkway, driveway or patio that virtually eliminates water runoff.
Water instead soaks into ground, where it is slowly absorbed. That's a better scenario than storm water runoff, which overwhelms municipal treatment systems and often carries contaminants such as motor oil and fertilizer.
The interlocking pavers are strong, durable, slip resistant and impervious to freeze-thaw cycles. They can be laid in a running bond pattern or a more natural looking herringbond.
Pavers will last two to three decades (longer than asphalt). The manufacturer recommends using only polymeric sand rather than just compacted sand. The polymeric sand locks the pavers into a grid that minimizes motion. The special sand is brushed into the joints between paving blocks then tamped down with water and pressure. This forms a membrane that is difficult from insects and weeds to penetrate from above or below.
The pavers are eligible for LEED (Leadership in Energy and Environmental Design) credits. These credits are part of a set of voluntary guidelines originally developed for the federal government and now administered by the non-profit US Green Building Council.
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