An interior French drain is a perforated drain trenched along the inside perimeter of your crawl space. It collects water that seeps through or under the foundation and carries it to a sump pump and basin, which pumps it away from the house. Cobb installs drains across the Upstate starting around $4,000; one sump pump and basin is included.
Signs you need a drain
- Standing water or mud in the crawl space after rain
- Water lines or stains on the foundation walls
- A vapor barrier with water pooled on top
- Rust on ductwork, or a dehumidifier that can't keep up
Why Upstate crawl spaces get wet
Red clay doesn't drain well. During heavy rain, water builds up in the soil around the foundation and pushes in at the footing. Homes on slopes and in low lots, common across the foothills and lake areas, get it worst.
How we install an interior French drain
- We trench along the inside perimeter of the foundation.
- Perforated drain pipe is laid in gravel to collect water.
- The drain runs to a sump basin at the low point, with a sump pump that discharges outside, away from the house.
- The crawl space is then lined so water stays under the barrier and in the drain.
Pricing
Drains are priced by the foot: about $35–$40 per linear foot, with a $4,000 minimum. One sump pump and basin is included; extra pumps are about $1,200 each. A French drain with sump pump is included in our Sapphire encapsulation package.
Where we work
We serve homeowners within about an hour of our Anderson shop, including Anderson, Greenville, Clemson, Easley, Seneca, Pickens, Powdersville, Greenwood and nearby towns in South Carolina and Northeast Georgia.