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Should You Install a French Drain In Your Crawl Space?

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In many encapsulation projects, crawl space French drain installation is an option. However, is it necessary to install a waterproofing drain in your crawl space? What about installing a sump pump? When faced with the cost of dealing with standing water in the crawl area, many homeowners raise these questions.

Remember that a crawl space that needs waterproofing can cause a humidity problem. A lack of humidity can cause mold and wood rot fungus. The fungus that causes wood rot might undermine your home’s foundation or, at the very least, cause drooping floorboards. When it comes to crawl space French drain installation, take care not to make a mistake.

For many years, HydroHelp911 has provided expert assistance. All of our services are entirely insured, and we provide free quotes. In addition, we’ll offer you an honest assessment of what needs to be done to resolve the issue and present you with a quote before beginning any work, so there are no surprises when it’s time to pay!

What Is a French Drain?

A French drain is a gravel-filled trench with a perforated or slotted pipe, also known as a curtain drain, perimeter drain, weeping tile, or agricultural drain. Using these drains, surface water or groundwater is directed away from a specified region, such as a home’s foundation.

Surface-level water is directed toward the lowest point of a French drain, where it seeps through the surface-level gravel and into the gutter. This gravel also prevents debris from passing through. The water is then gathered in the perforated pipe at the drain’s base and diverted from the house to a better location for daylighting or infiltration.

French drains differ from standard surface drains in that they collect water along the end of the drain rather than in a single location. As a result, French drains can also keep water from accumulating and pooling in some regions, soaking the ground below and causing water problems on the surface or down below.

Instead, the water is diverted to a more desirable site, such as a dry well or a designated region. For millennia, subsurface drainage systems have been in use to deal with everything from agricultural runoff to yard drainage.

These drains come in many shapes and sizes, but they all work the same way as the old French drain system. The first French drains were gravel-filled ditches. While many people believe the French drain originated in France, the name has come from Henry Flagg French, a former lawyer, and U.S. Assistant Treasury Secretary. They popularized them in his 1859 book Farm Drainage. French made his drains out of portions of roofing tile before later advancements added perforated drains to minimize clogging.

French Drain in Your Crawl Space

French drains transport standing water to a sump pump in the crawl space. These drains can also direct water away from the foundation wall. Waterproofing drains are required if there is water infiltration in your crawl area due to severe rainfall. Keep in mind that there are correct and incorrect methods for installing them.


Though you have water in your crawl space, the entire foundation wall may be wet, even if you can’t see it. This is because many homeowners and contractors will only put in a drainage system with standing water.

We recommend installing a complete perimeter trench system in the crawl area to address the current issue and any potential future issues. For example, after a gutter flood creates a conduit for flood water to enter your crawl space, no one wants to reinstall the vapor barrier five years later.


We’ve seen articles and DIY instructions instructing homeowners to bury the French drain pipe in crawl spaces as they would in a finished basement, but bear in mind that surface water is the biggest adversary. If the drainage system is installed at the footer and you reside in a complex soil or clay area, the vapor barrier may float, or worse, water may pool on top of the plastic before it can seep into the footer drain.

Groundwater, which can flow from the footer, the foundation wall, or the door is our main concern in crawl spaces. Ensure that the flood water has easy access to the drain tile you installed in the crawl space so that it can discharge to the outside sooner.


Once the water enters the French drain system, we usually use gravity to drain it out of the crawl area. Sump pumps connected to battery backup systems are a more reliable, long-term solution for us. We’ve seen landscaping businesses and homeowners lose track of gravity discharge lines over time and even destroy them. Because a 1.5-inch PVC discharge to a pop-up emitter is always visible, it’s easier to forget.


Finally, and perhaps most importantly, encapsulate the crawl space by overlaying and sealing the plastic while mechanically attaching it to walls and pillars. The first severe flood will move loosely put vapor barriers, so make sure your crawl space plastic is firm to drive flood waters into the French drainage system.

Benefits of Installing a Crawl Space French Drain

  • Moisture is removed – The significant advantage of this drain is that it keeps humidity out of your home. In addition, the pipe allows you to divert water from a higher to a lower place, such as your house or garage. As a result, you won’t have to be concerned about water flooding or cleaning up extra water in your home.
  • Eco-friendly  Going green is significant these days, and a French drain could help you get started. You can build your drain out of eco-friendly materials, which will benefit both the environment and you.
  • Prevention – Drainage correction may be able to save you thousands of bucks in foundation repair if you detect excess groundwater in your crawl space early enough.

French Drain Cost

Before beginning work on a project, it’s a good idea to estimate the cost of installing a French drain. The materials utilized, such as piping, aggregate, fabric, couplers, and end caps, determine the price of a French drain.

In addition, there may be additional licenses, fees, or equipment rentals to consider. According to many pros, a standard French drain costs roughly $20 to $30 per foot, but home-built French drain expenses may also include equipment rentals such as a trencher or compactor.

It’s critical to act if you have a flooded crawl space in your house. Water may swiftly wreak havoc on your home’s structure and lead to mold growth, rendering it uninhabitable.

Schedule a Free Consultation

Say goodbye to crawl space moisture issues with HydroHelp911. Our team of experts will assess your crawl space and provide the best solution for your home free of charge. Take the first step towards a safe, dry crawl space by scheduling a free consultation with us today.



For most water-diverting projects, the depth of a French drain should be between 8 inches and 2 feet. Still, related systems, such as those constructed around foundations and sub-ground living spaces and the bases of retaining walls, may be more profound.


The French drains should be placed between 2 and 5 feet away from the foundation. The precise distance to be dug for new drain lines to move water away from your property is influenced by a few things. First, choose an appropriate length: Look for areas where water naturally pools after heavy rainfall.


Allow 1–2 minutes for the water level in the trench to rise and enter the drain pipe. The French drain is operational if water flows out of the pipe end. However, the French drain becomes clogged if water does not flow out of the pipe end.


The holes in the PVC pipe must always face upward when installing a French drain. Only while designing a leaching field should holes be pointed downward. This is because we want the water poured or pushed into a pipe to drain into the surrounding ground.

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