French Drain vs Footer Drain - What is the difference?

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French Drain vs Footer Drain – what is the difference, and which do I need?

A French drain is a multi-faceted system that involves several components: Filter fabric, gravel and perforated pipe – set in a deep trench. It works with the physics of water, and is efficient at absorbing and relocating subsurface moisture. The big question often asked as it relates to the French drain is: Where does it get installed? Or more specifically – how far from the home and how deep should it be trenched… The answer to these questions really depends on the utility or purpose of the drain, and what issue is trying to be resolved.

If the main concern is a soggy lawn, a French drain system should be installed at the center (and lowest portion) of the area. It does not need to be any deeper than about 12” and there should only be about 2-3” of topsoil above it. At this depth, grass will continue to grow, but the shallow soil will allow for a more rapid absorption of surface water.

As it relates to the foundation, placement of the French drain is a bit more nuanced and complicated. Does it go up against the foundation? Does it offset a couple feet? Is 12” deep enough? Or should you go two or three feet?

To be fair, a soggy lawn next to the house is a problem for the foundation. In this case, installing a French drain as described above (at a depth of 12”) will be of great benefit. This situation often occurs along the side yard between homes, where the issue is especially problematic for the neighbor who has lower elevation. In general, a French drain placed 1-3 feet away from and parallel to the foundation will work great, and reduce the risk of foundation issues tremendously.

However, if moisture is coming up through the floor (meaning water is seeping down and around the foundation) the solution may change. In this case, the recommendation would be to install a French drain at or below the level of the bottom of the foundation, and possibly up against (at the foot of) the foundation. This provides a path of lower elevation for the water to go to, drawing water away from the foundation. Remember: water will always travel to the lowest area. By constructing a trench drain in this way, you are working with the physics of water. (As a side note, no surface drains should be attached to a footer drain – the goal of a footer drain is to REMOVE excess water. If surface drains are attached to a footer drain, even more water than before will end up at the foot of the foundation, negating the solution and likely making the issue worse.)

So what is the difference between a French drain and a footer drain? A footer drain IS a French drain – but its all about placement. When a French drain is installed up against and at the foot of the foundation, it is referred to as a “footer drain.” Besides being different, installing a footer drain is also more challenging because (1) it is significantly deeper, and (2) it is more difficult to dig due to its proximity to the house.

With everything discussed here, keep in mind that soil types matter – soil conditions differ by area and there is no one size fits all answer. Dallas homes with similar topography but in different areas will have a unique set of issues. Not all clay is created equal! Hope you enjoyed the article, and that you found it helpful.