An interior French drain works by channeling excess water that has already seeped into a basement or crawlspace, collecting it in a perforated pipe surrounded by gravel, and directing it to a sump pit where a pump then removes it from the foundation, effectively preventing water from accumulating and damaging the structure; essentially, it acts as a drainage system installed beneath the basement floor to divert water away from the foundation walls.
Key components of an interior French drain:
- Trench: A channel dug along the perimeter of the basement floor where the pipe is laid.
- Perforated pipe: The main drainage pipe with holes along its length to allow water to seep in from the surrounding soil.
- Gravel bed: A layer of crushed stone placed around the pipe to facilitate water flow and filter out sediment.
- Sump pit: A collection basin where the water from the drainpipe is directed and then pumped out by a sump pump.
How it works:
- Water infiltration: Groundwater or surface water seeps through the basement walls and floor, reaching the gravel surrounding the perforated pipe.
- Water collection: The perforated pipe collects the water flowing through the gravel.
- Gravity flow: The water travels through the pipe by gravity, moving towards the lowest point which is usually the sump pit.
- Sump pump activation: As water accumulates in the sump pit, the sump pump turns on and pumps the water out of the basement.
Important considerations:
- Slope: The trench should be sloped towards the sump pit to ensure proper water flow.
- Drainage fabric: In some cases, a drainage fabric may be installed around the gravel to prevent soil particles from clogging the pipe.
- Maintenance: Regular inspection and cleaning of the sump pump and drain system is essential to ensure optimal functionality.
