Foundation services
Interior French drain for basements
An interior French drain in a basement is a perforated pipe laid in gravel just inside the wall, next to the footing, under a strip of floor.
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Written by HyreFoundation Research Desk Primary-source research and fact checking
The short answer
An interior French drain in a basement is a perforated pipe laid in gravel just inside the wall, next to the footing, under a strip of floor. It catches water at the wall-floor joint and under the slab and carries it to a sump. Placement relative to the footing matters most.
Key takeaways
, the part of an interior system that collects water.
Pipe set high on the footing misses water rising underneath.
so water inside the cores can drain.
Pump, discharge and backup are part of the design.
How is an interior drain tile system installed?
A strip of floor, usually about a foot wide, is removed along the walls that leak.
Soil is removed beside or onto the footing. The installer should explain which and why.
Perforated pipe in washed gravel, sloped to the sump. On block walls, small holes are drilled in the bottom course.
New concrete over the trench and the pipe joined to the sump pit.
What moves the price
Priced mainly by the foot. We publish no price figures until we hold enough sourced, dated quotes; see what drives foundation costs.
| Factor | Why it changes the number |
|---|---|
| Footage | Which walls get drain, and how much. |
| Wall type | Block walls need weep holes; poured walls do not. |
| Sump package | New pit, pump and backup, or tying into an existing one. |
HyreFoundation publishes no national average price for this work. Depth to bearing, soil, access and method vary enough between two houses on the same street that a single figure would mislead.
When is an interior drain the answer?
When water enters at the wall-floor joint or through the slab and outside fixes are done. For a house with a working sump and only one wet wall, a partial drain on that wall may be enough. For broader basement options see interior basement waterproofing.
What to ask before you sign
The full checklist is on choosing a foundation contractor.
Where this goes wrong
Water under the slab must rise to reach it. Ask for the design reasoning.
Iron-rich water and silt can clog pipes. A cleanout lets you flush it.
A single wet wall may only need a partial run.
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Tell us about the work
Three short steps: the job, your home, and how to reach you. Nothing goes to a foundation company unless you agree.
A straight answer first. A person reads it and replies by email, free and with no obligation. Matching is not live yet, so this is not a quote. If a wall is moving or a door frame has racked out of square this week, call a structural engineer first.
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A person at HyreFoundation reads the request and replies. Matching is not live yet, so this is not a quote.
Questions
Is interior drain tile worth it?
How long does an interior French drain last?
Can interior drain tile clog?
Does it work in a crawl space?
Written and audited by
HyreFoundation Research Desk
Primary-source research and fact checking
We read the model building code, the federal soil and moisture guidance and the insurer position ourselves, and we publish each figure with the document it came from and the date we retrieved it.
Where a number cannot be traced to a primary source, we say so instead of printing it. HyreFoundation does not inspect, engineer or repair foundations. Authorship is organizational: this desk, not a named persona.
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Sources & retrieval dates
Information on this page is general and varies with soil, climate, foundation type, building code, insurance policy and circumstance.
It is not engineering, insurance or legal advice, and no page can tell you whether your house has a structural problem: that needs a licensed professional on site.
HyreFoundation is an independent foundation resource, not a repair contractor or an engineering firm, and does not perform, supervise or warrant foundation work.