French drains are a cost-effective addition to any house.
Besides preventing flooding, they also help reduce long-term water damage to your property.
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How Much Is A French Drain?
The total French drain cost is estimated per linear foot.
But the price also takes into consideration whether the drains are for the interior or exterior of the property.
Both systems have pros and cons that may affect the availability and final installation costs.
Thankfully, materials for both systems are relatively cheap.
However, in the case of an internal French drain system, you may need to install a sump pump to transport water outside.
This system’s efficiency is also lower than external French drains, as it does not prevent water from reaching the house foundation.
On the plus side, interior drains need less maintenance as they are less prone to get clogged by dirt.
Exterior drain systems go around the house foundation.
This system is cheaper than interior ones and effective in preventing water from reaching the house foundation.
One of the drawbacks is that the installation costs are higher.
To install the system, a contractor will need to dig up around your yard and remove everything in the path. This may include gardens, shrubs, driveways, and decks.
Average Cost Of A French Drain System
Once you’ve established which kind of drain system is the most suited to your home’s needs, you can start calculating the average total costs.
| Cost per Linear Foot | Installation Cost per Linear Foot | Total | |
|---|---|---|---|
| Interior French Drain | $55 | $70 | $125 |
| Exterior French Drain | $35 | $60 | $95 |
Interior French Drain Average Cost
The average cost for an interior French drain is $55 per linear foot.
The average installation cost for this kind of system is $70 per linear foot.
Thus, the average cost of an installed interior French drain system is $125 per linear foot in total.
Additionally, you may have to acquire a sump pump, which carries an average cost of $1,000, as well as an installation fee.
On average, a sump pump installation on a concrete floor costs $3,200.
This means the total cost for an installed sump pump will be, on average, $4,200.
For several reasons, the installation of an interior system is more expensive.
For one, basement floors are generally concrete, which means it will require more work and machinery to break them up to install the drain.
Pro Tip: Permeable geotextile fabrics are often used to cover the pipes, as this prevents the filtration of debris that would, over time, clog the system.
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Exterior French Drain Average Cost
The average cost for an exterior French drain system is $35 per linear foot.
Meanwhile, the average installation cost of this kind of system is $60 per linear foot.
This means the total for an installed exterior French drain system is $95 per linear foot.
For this kind of system, there is no need to install a sump pump, as the water drains by gravity.
However, some properties may need to drain significant rainfall water. In those cases, a dry well is required, which carries an installation cost of $2,500 on average.
Cost Of French Drain Per Foot
Exterior French drain systems, also called drain tiles, cost between $10 and $90 per linear foot.
However, the less expensive drains are only for simple yard systems.
If you require a foundation water management system, the cost will be closer to the higher end of the scale.
On the other hand, the cost for an interior French drain system ranges between $35 and $95 per linear foot.
If a sump pump is required, you’ll have to add the additional cost of the pump and its installation.
How Much Does a 100-Foot French Drain Cost?
The average cost for an interior 100-foot French drain will be $5,500.
This cost doesn’t include a sump pump or its installation, which may be needed depending on your house’s current drainage system.
A 100-foot exterior French drain system is less expensive. The average cost is $3,800.
However, this doesn’t include landscape repair or the installation of a dry well if needed.
| Cost per 100 Feet | Installation Cost per 100 Feet | Total | |
|---|---|---|---|
| Interior French Drain | $5,500 | $7,000 | $12,500 |
| Exterior French Drain | $3,500 | $6,000 | $9,500 |
French Drain Cost per Meter
An exterior French drain system costs between $110 and $280 per meter.
The cost of an interior French drain system is between $115 and $310 per meter.
| Cost per Meter | Installation Cost per Meter | Total | |
|---|---|---|---|
| Interior French Drain | $115-$310 | $225 | $340-$535 |
| Exterior French Drain | $110-$280 | $195 | $305-$475 |
Factors That Affect The Cost Of A French Drain
Various factors will affect the installation cost of a new French drain system, whether it’s in the interior or on the exterior of the property.
These factors include labor costs, required permits, and the type of material used.
Labor
Labor costs generally run between $40 and $90 per hour for installation.
An interior French drain system will generally require breaking up the floor of a basement, which is usually concrete. This will take more time and special machinery.
The job will be completed faster in case of an earthen floor.
Meanwhile, with an exterior system, the type of soil where the excavation is needed will also affect the labor cost.
Rocky and heavy clay soil are hard to excavate, and the process will take more time.
Did you know? French drains have been used as a drainage system for over 160 years. They were named after Henry Flagg French, who designed them in 1859.
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Permits
Many states require a permit to excavate a property’s basement or the premises.
Generally, these permits cost between $50 and $100.
Once the contractor takes out the permit, an inspector might go to your home to verify that the installation meets the local codes.
Type and Material
The material costs for a French drain installation are relatively low.
For exterior systems, you’ll need pea gravel with an estimated cost of $30 to $ 250 per cubic yard.
Additionally, you’ll need the perforated pipes, which generally cost between $0.50 and $3 per linear foot.
The cost will depend on the quality or if they come with a nylon fabric cover to keep dirt and sediment from filtering into the pipe.
For interior systems, you’ll have to add the sump pump, if necessary, and concrete to cover the trench.
Location in Home and Accessibility
Installation costs are less expensive in spacious basements because access to key sections is easier.
However, you will be charged an extra 5% to 10% for an interior installation system in a crawl space.
Size, Length, and Depth
Most contractors estimate installation costs by linear feet.
However, the width and depth of the trench required will also be considered when estimating the cost per linear foot.
Depending on your home needs, the depth should be between 2 and 8 inches.
A professional contractor will also be qualified to determine the necessary width.
Additional Costs and Considerations
When installing a new French drain system, you’ll encounter some unforeseen expenses due to the damage caused by the excavation process, whether in your basement or your lawn.
Landscaping Repair
After installing an exterior French drain system, the yard will need various repairs, such as replanting shrubs, reseeding grass, or laying sod.
These kinds of tasks aren’t included in the drain system installation service.
Homeowners might pay between $3 and $5 per square foot for minimal landscaping services to return their yard to its original condition.
Retaining Wall
Water naturally drains through the yard in houses located on slopes and hills, making them prone to drainage problems.
A retaining wall may be an excellent alternative to this problem, especially if the property is under storm runoff.
The cost of a retaining wall is relatively high.
The cost for a dry-stack retaining wall starts at $3,500.
Retaining walls made of concrete cost between $9,000 and $12,000.
Dry Well
When the property doesn’t have an ideal location to drain the thousands of gallons of water the system collects, it will be necessary to install a dry well or irrigation ditch.
A dry well installation costs between $1,000 and $4,100.
Dry wells can usually take one of three forms:
- A gravel-filled hole cleared by hand. It’s also referred to as a seepage pit.
- A prefabricated plastic container.
- A poured concrete container.
Sump Pump
Interior systems work differently than exteriors ones – gravity drainage doesn’t work in the case of interior systems.
That’s the main reason most interior French drain systems require the installation of a sump pump that will transport the collected water to ground level.
Who Installs French Drains?
You should call a plumbing company to install a new French drain system on your property. Try comparing quotes from a few different plumbers in your area to get the best price.
However, landscapers can also handle these kinds of installations and sometimes offer them as an additional service.
Pro Tip: To encourage the correct movement of water downwards, French drains need at least a 1% slope.
How Much Does A DIY French Drain Cost?
Installing a French drain system would appear to be a simple task, leading some homeowners to consider making it a DIY project.
However, a professional setup is always advisable, as a faulty drainage system can do immeasurable damage to your property.
But if you decide to do the installation yourself, you’ll need several tools and equipment, such as a sod cutter, marking flags, level, wheelbarrow, PVC pipes, and more.
The average cost of a DIY French drain installation is $20 per linear foot.
When To Use A French Drain
The purpose of French drains is to absorb and transport groundwater away from gardens and around buildings’ foundations.
Their primary goal is to move trapped water to a particular area.
These kinds of drains are mostly used in soil with frequent saturation from rain or flooding.
How Long Does It Take For A French Drain To Work?
French drains are designed to start working as soon as the installation is finished.
If water doesn’t flow out of the pipe when expected, the system may be clogged, or the installation wasn’t done correctly.
How to Tell If A French Drain Is Working Properly
One of the most frequent concerns of homeowners is if the French drain system is working correctly.
Over time, the systems can get clogged, reducing the draining efficiency.
There are several easy ways to tell if it is working correctly.
- Check the basement walls. One of the main purposes of a French drain system is to protect the house’s basement and foundation. If you notice mold, leaks, or moisture on your basement walls, that could indicate that the draining system is not working correctly.
- Check the lawn. If you notice standing water or water forming a pool in certain areas of your property, that may indicate that the draining system is clogged or that the French drain system was not installed with enough inclination.
- Examine the pipes. If you think a section of the system is clogged, you can dig up the channel and inspect its condition. An indication that it’s blocked would be finding standing water on the track or over the pipe itself.
- Check the endpoint of the drain system. Using a garden hose, direct water toward the draining ditch from a short distance uphill. The water should take one or two minutes to reach the disposal area. If it takes longer, the system might be clogged.
Did you know? The wider the trench, the more water can get into the system. However, a contractor will consider the yard size and the drainage needed to provide you with an accurate trench width.
What Is A Sump Pump, And How Does It Work With A French Drain?
On occasion, exterior French drain systems aren’t efficient enough to prevent moisture from reaching the basement walls or the house foundations.
If this is the case, you’ll notice moisture, mold, and mildew building up on the basement walls.
To prevent this, you may need a sump pump.
A sump pump is an electrical pumping system that sits underneath the basement.
Its primary function is to pump out the water collected in the sump basin.
The need to install a sump pump in your basement will depend on the seriousness of your water problems.
How To Unclog A French Drain
Unclogging a French drain system is a process you can do yourself with the proper equipment.
However, you can also contact a professional to unclog and maintain your system.
If you’re doing it yourself, you can start by using a garden hose to run a large amount of water through the French drain.
If the clog is minimal, this may be enough to remove the debris that’s affecting its functioning.
If the system is still clogged, you’ll need to rent an electric sewer snake.
This machinery consists of a motor-powered cable spool with cutters at its tip that is inserted into the drain.
The average price for a half-day rental is $60.
Here is how to unclog the system with an electric sewer snake.
- Uncover the entrance of the French drain and feed the cable into it. Turn on the auger and keep pushing the cable inside. Remember to use gloves to protect your hands.
- If there is a point where you start feeling resistance, stop and retract the cable. This will free the cutters and will allow you to move forward again.
- Move the cable back and forth slowly every time you feel you’ve reached a clog.
- Large clogs are harder to remove. Sometimes, you must remove the cable entirely using the reverse switch. Clean the cable with a wet rug and start the process again.
- Once the drain system is clean, insert a hose so water can flush any remaining debris.
Where To Put A French Drain
French drain systems are often installed along the driveway and the property’s foundations.
The latter is to help keep the basement and crawlspaces dry.
These systems are also installed in specific areas of the lawn, which tend to accumulate standing water.
How Deep Should A French Drain Be Buried?
When installing a French drain, the system’s depth should be between 2 and 8 inches.
That would be enough to divert water efficiently.
However, other systems, such as those installed around underground living spaces, may need to go deeper.
Pro Tip: Placement of the French drains is essential. You don’t want the system passing through important areas like playgrounds.
Does Homeowners Insurance Cover French Drain?
Home insurance doesn’t cover French drains.
Your policy will cover rain and flood damage if you have water backup coverage.
However, you’ll have to get a separate policy if you want the actual system covered.
How Long Does A French Drain Last?
French drains are a convenient long-term solution for drainage problems.
Over time, however, excess salt, debris, and clay get past the fabric protecting the pipes, making the system less effective.
Generally, a French drain can last 10 to 30 years with proper maintenance.
Where Does Water From A French Drain Go?
Depending on your property’s characteristics, water accumulated by the drain system can be diverted to:
- A drainage ditch
- The street
- A low area of your property
- A dry well
Are French Drains Necessary?
Standing water in the lawn caused by poor drainage may lead to significant problems for your property.
This includes yard and foundation damage that will be expensive to repair and jeopardize the property’s value.
Additionally, French drains help prevent flooding.
Are French Drains Worth It?
Installing a French drain system in your property is a cost-effective way to prevent foundation damage caused by standing water.
This kind of damage is not only expensive to repair, but also affects the value of the property.
The upfront investment for an exterior system is $3,800 per 100 feet.
Interior systems tend to be more expensive, with an average cost of $6,500 per 100 feet.
In addition, you may have to factor in unforeseen expenses such as landscaping repair, a sump pump, permits, a dry well, and more.
But with a life span of 10 to 30 years, and minimum maintenance required, the pros of installing French drains in your property outweigh the cons.
Did you know? One of the main benefits of investing in a French drain system for your home is that it will increase your property’s value. It will keep your house looking good when showing it to potential buyers and proves that the property has been taken care of.
Are French Drains Worth the Money?
The installation of a French drain system requires a moderate upfront investment.
However, the benefits of having efficient drainage in your home make it a cost-effective investment.
