French drain / crawlspace

I would be thankful if some one can let me know if it’s wrong or right to build french drain in crawlspace ?

Any images?
We’re not mind readers.

is it functioning as intended ???



Interior perimeter drain tile, french drains etc are common water mitigation systems. But that does not make them right or even effective. Too many variables without more information.

Kulraj, this type may work keeping the moisture out of the crawl space:


Hi thanks yes its the same type as photo

99% of the time water in a crawlspace is the symptom to the problem. The source of the water and how it’s getting in is the problem. That 1% for me is those houses built on bad lots with high ground water table or poorly draining soils.

1 Like

Randy, is it really only 1%? there are entire neighborhoods where house sump pumps turn on and pump water out every 10-30 minutes. Many of those houses get flooded when something goes wrong with the sump pump or two.

1 Like

Simon, my reference is for houses built on acceptable soil. I have areas with pockets of prairie soil (very flat topography) that has a water table 12" to 24" below the ground surface year round. Everyone one of those neighborhoods pump water out of their crawlspace goes in the crawlspace next door and they pump it out and it goes around the block. That soil should only have raised slab foundations. This prairie soil is so wet you can’t build a basement, and the few that did the walls shoved in.

1 Like

Yeap, crazy!!! Any idea, why this is being approved by AHJ.

There are no building codes

One option is to put a French drain around the perimeter of the foundation that terminates below the footing level to intercept the ground water and lower the water table. Drain to daylight if possible otherwise drain to a sump pump.

1 Like