Difference between Yard and French Drain?
Yard drains are typically installed with a solid pipe 10 inches deep in the ground and are designed to carry water from point A to point B. Yard drains are primarily used to carry large amounts of water from rooftops and low areas away from property. If the site is not sloped enough for water to run off the property on its own, then the water will start to find low spots and can stay there for over 10 hours after heavy rain, if you have good soil. But if the soil is heavily compacted or mixed with clay, you're in trouble. In such a situation, water can remain for weeks, creating mold, weeds, smell and attracting insects like mosquito. Stagnant water over time will get closer to your basement foundation and might seep into it, making it weaker and creating cracks.
French drain is installed at the same depth of 10 inches from the ground and serves to collect water from the soil and from the soil surface. Unlike Yard Drain, the pipe we use is called corrugated and has small holes along the entire length of the pipe so that water can seep into the pipe and drain in directions we want. The cloth sock worn over the pipe is designed to prevent dirt and sand from getting inside the pipe and blocking it. Installing a French drain is a bit more complicated than a yard drain. Once the trench is open 10 inches deep, we run corrugated pipe, also known as weeping tile, with 3/4 clean gravel and wrap everything in geotextile fabric to keep dirt and sand from blocking the gravel and pipe. For best performance, it's best to leave the trench open, but there's also a way to backfill the trench with enough soil and lay down sod, making it nearly invisible.