Drive around Hendersonville after a heavy rain and the problem is visible: water sheeting off hillsides, pooling against foundations, finding the path of least resistance straight into crawl spaces and basements. The clay-heavy soil that makes WNC gardens great makes it terrible at letting water move away from a home.
What a French drain is
A French drain is a sloped trench filled with washed gravel, with a perforated pipe at the bottom wrapped in filter fabric, that intercepts water before it reaches the foundation and carries it to a safe discharge point.
Exterior vs. interior
- Exterior French drain: dug along the foundation footing on the outside, the most effective at stopping water at the source. More expensive and more disruptive.
- Interior French drain: installed inside the crawl or basement perimeter, paired with a sump pump. Faster, less landscaping disruption, slightly less effective at protecting the wall itself.
Common installation mistakes
- Corrugated pipe with the holes facing up instead of down.
- Skipping filter fabric — clay clogs the gravel within a year.
- Insufficient slope. Anything less than 1% grade and water sits.
- Discharging into a closed sump that floods the crawl during heavy rain.
What we install
Rigid SDR-35 perforated pipe, double-wrapped filter sock, washed #57 gravel, daylight discharge wherever grade allows. Ten minutes of grade analysis up front prevents a decade of water problems.