French Drain Fabric 101 – What to Buy and How it Works
Best Fabric to Increase Longevity of Drainage Systems
French drain systems that are installed correctly are meant to last a lifetime. While other contractors may skimp on their French drains, French Drain Man utilizes only the best materials and techniques for our systems. We’re meticulous about every detail that can strengthen your French drain system and ensure that homeowners have a low-maintenance, yet powerful drainage solution. That includes installing professional-grade, DOT-certified French drain fabric that is double punched.
Non-Woven Geotextile French Drain Fabric
Some contractors may cut corners when installing your French drain, which may cause it to need yearly maintenance and repairs. At French Drain Man, we install French drains the right way the first time and only use the best, long-lasting materials.
Construction crews are putting French drains underneath the new road. There’s a lot of money being spent to ensure they’re doing it the right way. We follow the same blueprint for our French drains, using a DOT-certified French drain fabric. We use a non-woven double punched geotextile fabric that’s designed to leech water away from your system.
We always try to educate our clients and tell them, “Look, you don’t want to use landscape fabric. Landscape fabric does not drain. Weed barriers and fabrics that are meant for structural strength behind a retaining wall are not intended for a French drain.”
When you have a DOT-certified, approved fabric, it’s not going to deteriorate like the landscape fabric pictured below.
That’s the problem with these thin fabrics. They just biodegrade and break down. They’re junk in no time. Instead, we like to use a four-ounce fabric in high flow applications and an eight-ounce in low flow applications.
Fabric FDM Uses:
Fabric Designed to Move Water
The eight-ounce obviously is a heavier fabric. It’s going to last lifetimes; generations. Below, you can see the guys installing the eight-ounce French drain fabric.
This is a really big French drain system that we’re replacing with our 6-inch corrugated pipe. We’re going to set the corrugated pipe right on top of the French drain fabric. That way there’s not a bed of stone holding water underneath the French drain. Iron ochre, tree roots, and shrub roots won’t take this French drain out.
When a rain event is over and the corrugated pipe is done moving water, we’re going to be right at the bottom of the trench. There’s only going to be a trace of water left in the corrugated pipe. That pales in comparison to PVC, where you have four inches of stone beneath your French drain holding water in the void of the stones. If you cut a trench in clay and put sand or draining stone in the bottom of that trench, your system will hold water.
How Geotextile Fabric Works with Your French Drain
The diagram below was done based on a road construction scenario. The diagram shows a pipe, a burrito wrap, and all the native soil. They have a magnifying glass zooming in on the French drain fabric.
Notice the drainage stone on the left. In the middle of that magnifying glass is the french drain fabric. Then, you have your soil on the right side of the magnifying glass. This diagram shows what geotextile fabric looks like immediately after construction. Now, that fabric isn’t going to perform its best when initially installed. It will perform, but not at maximum efficiency until all the sediment washes through the double-punched fabric.
Over time, as more sediment washes through your French drain fabric, the better the soil filter zone becomes. The soil filter zone that forms between the double punched non-woven geotextile fabric and the native soil is key. That’s why our double-punched fabric continuously improves over time, rather than deteriorating and causing issues for your French drain like other fabrics.
Our fabric works better each and every year. The drains in your system work better. That’s because we punched the fabric twice to allow the turf growing over it to root through the fabric.
As roots grow through our French drain fabric, fabric with two different size holes, those little roots act as thread and expand to keep the holes open. Now, that water is free to flow down our French drain fabric and leech away from your system.
Withstanding the Test of Time
To show you how well our French drain fabric withstands the test of time, we’ve unearthed French drain fabric that was installed a decade ago.
This is a four-ounce fabric that’s in great shape after ten years. I sawed through the turf with a sharp blade knife to peel it back and unearth our 10-year-old French drain fabric. You can see how clean it kept the French drain. The voids that move water are still open, preventing the dirt from migrating into the French drain system. In fact, this French drain is probably cleaner than the day we put it in because the dirt washes through the inlet. You can see that this stone is cleaner than it’s ever been, even a decade later.