By Glenda Taylor | Updated Apr 7, 2022 11:47 AM

Modern building practices incorporate methods to direct rainwater away from a home’s foundation. Unfortunately, some older houses may have been built without considering how water would drain. Or something may have changed over the years, like the collapse of a perimeter exterior drain tile that no longer carries water away so it’s backing up in the basement.

Pooling water in or around the exterior of a crawl space or basement can lead to structural damage to a foundation. Water in a basement can damage possessions and lead to mold growth. Installing a French drain (which is different from a basement drain) is the fix many homeowners opt for, and French drain cost ranges from a low of $500 for minimal repairs to as much as $18,000 for installing an extensive system. Most homeowners will pay an average of around $5,000.

A French drain is a generic term that describes multiple types of drainage, and it goes by many names, including “weeping tile,” “trench drain,” and “channel drain.” In general, a French drain consists of an excavated trench where a perforated pipe is laid and surrounded by pea gravel that acts as a filter to keep sediment out of the pipe. Water collects in the pipe and then drains safely away.

Cost varies by the extent of the excavation as well as the length of the drain itself. Expect to pay between $10 to $50 per linear foot to install an exterior French drain. Interior French drains are often costlier due to the need to break out concrete in a basement floor to excavate beneath and install the drain, so this type of drain runs an average of $40 to $100 per linear foot. In most cases, homeowners will want to hire a professional to do the job.

While the national average for having a French drain installed is about $5,000, the cost will vary from community to community based on the going price of labor and unforeseen issues the contractor might run into when installing the system. The cost of materials used in the construction of the drain and accessibility can all affect the final price.

Installing a French drain can be labor-intensive, especially if workers need to break out a basement floor with a jackhammer. The average labor cost runs about $50 to $100 per hour, and if an area is difficult to access, such as trenching beneath a concrete footer, it will take longer to excavate than digging in soft soil, so labor costs will rise.

Many communities require pulling a permit before doing any type of excavation in a basement or around a home’s exterior perimeter. On average, expect to pay about $50 to $100 for a permit. When the contractor takes out a permit, it serves as an official notification of the type of work to be done. As a requirement, an inspector might check to ensure the trench is secure and that the gravel and drain pipe meet local codes.

The cost of materials to install a French drain is relatively low; most of the cost is labor and overhead for equipment use. The total cost of the perforated pipe averages $50 to $200, and the cost of the pea gravel is about $500 to $1,000. For calculation purposes, the pipe itself typically runs about $0.50 to $3 per linear foot, depending on the quality and whether it comes with a “sock,” which is a nylon fabric cover that helps keep sediment from filtering into the pipe.

Interior French drains are more expensive to install than exterior drains because they require more labor to excavate through a concrete floor. On average, homeowners can expect to pay between $5,000 and $13,500 to have a French drain installed in the home. The required size of the drain will also play a role in the cost—most basements will need between 100 and 150 feet of installed French drain.

The cost to install a French drain in a basement runs approximately $40 to $100 per linear foot, so the longer the drain, the more it will cost. Relatively shallow exterior French drains (called curtain drains), such as those installed to drain the water from a downspout to a street curb or a catch basin in the yard, will cost less because there’s no concrete to break out. Expect to pay between $10 and $35 per linear foot for an exterior French drain.

Several unforeseen expenses may be associated with installing a French drain because the excavation process will damage a basement floor or tear up an existing lawn. Concrete repair work or landscaping services may be necessary, which will add to the overall cost. The following factors will apply in some cases and impact the final cost of installing a French drain.

Some areas require an inspector to sign off on the work before a French drain can be covered with gravel, soil, or concrete. The cost of the inspector might be paid by the community, in which case it won’t be an added fee for the homeowner. However, if a private inspector is hired to check the drain, it could add $150 to $250.

Digging through heavy clay or rocky soil can be a slow process, especially if a French interior drain is installed in a basement where it’s virtually impossible to use heavy equipment to dig. Digging by hand through tough soil will take longer than digging through relatively soft ground. Contractors typically charge $50 to $100 per hour for each worker, so the type of soil they’re digging through can affect labor costs.

Installing an exterior French drain requires digging through the existing yard, resulting in the need for various types of landscape repairs. The company that installs the drain is unlikely to repair the lawn, replant shrubs, lay sod, or do other landscaping tasks. Homeowners can expect to pay anywhere from $4 to $6 per square foot for minimal landscaping services, such as overseeding grass, to up to $40 per square yard to have new sod installed.

A French drain will carry water away from the foundation, but if there’s no place to discharge the water, it could pool elsewhere in the yard. One solution for discharging the water from a drain is the installation of a drainage ditch. This may require resloping or changing the grade of the property. It’s a relatively simple project, however, that shouldn’t add more than $0.50 to $1 per square foot to the final cost.

Houses built on slopes and hills are prone to drainage problems as water naturally drains through the yards. If your home is in the path of storm runoff, you may want to consider installing a retaining wall to reroute excess water away from your yard. This could be a pricey fix, starting around $4,000 for a dry-stack retaining wall and ranging from $10,000 to $13,000 for a retaining wall made from poured concrete.

Puddling and pooling water in a yard can kill grass and other vegetation. A shallow exterior drain can direct the water to a designated holding spot, sometimes called a vertical French drain. A vertical drain can be as simple as a catch basin filled with rocks or gravel that holds excess water, or it can be more elaborate and feature buried tanks that collect the water and then allow it to drain off slowly. A vertical French drain starts around $100 to $300 and goes up from there, depending on the type.

A sump pump may be required for an interior or an exterior French drain if the water cannot naturally drain away via gravity. A sump pump sits in a sump bucket, and when water from the drain fills the bucket to a prespecified level, the sump pump turns on and pumps the water to the ground’s surface. If a sump pump is necessary, it can add another $150 to $300 to the cost.

French drains are suitable for both interior and exterior use, and the price will vary depending on which one is necessary to correct the drainage problem. The best and most affordable solution is to install adequate drainage when the house is built. At that time, the contractor has easy access to the ground beneath the basement and around the basement’s perimeter. That’s also the time to grade the surrounding yard to encourage water to drain away from the house.

While a French interior drain can be installed at any time, it’s usually installed in existing homes experiencing basement seepage or puddling. This is a significant project due to the need to break out the concrete floor and trench beneath to install the drain. The cost per linear foot to install an interior French drain ranges from $40 to $100, depending on the degree of accessibility and difficulty.

During new construction is the best time to install an exterior French drain—also called drain tile—around the perimeter of the basement before backfilling. At this time, installing the drain is a simple matter of adding a few inches of pea gravel (local codes will determine how much), laying the perforated pipe in the gravel bed, and covering the pipe with more gravel. Installing a drain at this time can cost $10 to $50 per linear foot. Trenching to install a yard drain in an existing yard can run from $30 to $90 per linear foot.

Water and foundations don’t mix. Even in relatively dry climates, making provisions for occasional rain and runoff will prevent water damage down the road. The initial investment in a French drain varies. At the low end, it can cost as little as $500 to install a shallow exterior drain that will protect the foundation or other areas of the yard from puddling, making it an affordable and relatively simple solution.

At the other end of the cost spectrum, homeowners could pay as much as $18,000 for a French interior drain that eliminates basement flooding. In nearly all cases, the money spent on preventing water damage is an investment in the home’s value.

Homes in regions that receive substantial rain are at greater risk of damage from standing water and flooding, both inside the house and in the yard. While there are numerous ways to prevent a soggy yard and reroute water, installing a French drain is among the more common options. French drain costs range widely (from $500 to $18,000) and will vary based on where the French drain is located (inside or outside) as well as its length and depth. However, most homeowners will pay around $5,000.

Unless a rain garden is already established in a yard and filled with various water-loving plants, most homeowners are not fond of excess water pooling on the lawn. When grass and most plants are underwater for more than a few hours, it can increase the risk of root rot and fungal disease. Having the water diverted through the installation of a curtain drain averages $1,000 to $5,000, and it can improve the overall condition of the lawn.

A retaining wall can protect a house and yard from natural runoff if the home sits on a hill or slope, but the retaining wall itself can be impacted by lateral pressure from the water that builds up on the back side. In time, this pressure can damage the retaining wall, so some contractors may recommend installing a French drain along the rear of the retaining wall to ease some of the water pressure. The drain, usually installed when the wall is built, will increase the project’s cost by about $25 to $50.

The most common reason for installing an interior French drain is flooding in the basement. Flooding, even if it’s just an inch or less, can lead to high humidity levels, damage wood framing, destroy stored possessions, and reduce the home’s salability. This is one of the more costly French drain projects, averaging $5,000 to $9,000, but it could run as high as $18,000 or more, depending on accessibility and size.

While strict building codes require drainage provisions for newly constructed homes, houses were often built with substandard or nonexistent drainage systems before communities adopted those codes. Suppose it’s possible to excavate around an existing home’s outer foundation. In that case, an exterior drain system can be installed at an average cost of about $1,000 to $10,000, depending on the depth and length of the drain.

Installing a French drain can be a DIY project in some cases, but because it involves excavating, most homeowners will want to hire a professional contractor. Professional installation is especially beneficial if you’re installing an interior French drain and need to break through concrete or if your soil is dense or rocky. Professionals will have the equipment and skill necessary to deal with these complications. Remember that DIY installation doesn’t come with a guarantee, while a contractor will likely warranty the work for a year or so.

Installing a method of drainage is essential to prevent basement and yard damage, but it’s a pricey prospect for many at an average national cost of around $5,000. A large percentage of the price of a professionally installed interior French drain is the cost of labor. In contrast, the price of an exterior drain can be impacted by the cost of using heavy equipment, such as trenchers, or the need for landscaping repairs after installation. Consider the following factors, which can save on the overall costs.

Most foundation and drainage contractors will come out and look at the situation and give the homeowner a price for doing the work. Like all major projects, getting two or more bids before hiring a contractor is a good idea. In addition, by asking the following questions, you’ll know what you’re getting for your investment.

Correcting drainage problems in a home or a yard can be pricey, and installing a French drain can run anywhere between $500 to $18,000, depending on the size and extent of the problem. While fixing the drainage issues is an investment in the property, homeowners are likely to have a few questions.

If the project only requires a shallow curtain drain, you may be able to DIY it. Most of the time, however, this is a project best left to the pros. On average, perforated pipe runs $50 to $200, while pea gravel costs $500 to $1,000. Renting a walk-behind trencher can set you back $100 to $200 per day.

Most homeowners insurance policies do not cover the cost of installing a French drain. Still, if you’re worried about drainage in the future, you may be able to add a French drain rider to your existing policy for an additional fee.

When installed correctly, a French drain should last at least 30 to 40 years.

Depending on the rules in your community, you may be able to discharge the water to a storm drain, an irrigation ditch, or a dry well.

The average depth of the trench should be a minimum of about 18 to 24 inches below the area that needs drainage protection. That means below grade in a yard and below the floor in a basement.

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