French drains are typically several feet deep with a perforated PVC tile at the bottom of a 2’ wide ditch filled with gravel. This allows surface water to escape down through the gravel to the drain pipe.
A lot of foundation problems are caused by the lack of downspout drainage. You may have gutters, you may have a downspout, but unless you have an underground downspout drainage system, water is just pooling in the soils around your house and will find its way into the basement.
