If you’re in search of accurate costs to install a French drain around your foundation, you’ve come to the right place.
Here’s what you’ll learn by the end of this article:
- How French drains work
- Four different kinds of French drains and what they’re used for
- Signs you need an exterior drainage system
- Cost estimates for adding one to your property
- How to save money when installing a French drain
It’s estimated that over 60% of homes with basements or crawlspaces leak at some point through the foundation wall. Your concrete works tirelessly to stop water from coming in but can only resist so much.
Constant hydrostatic pressure created by rainwater or groundwater is likely to find its way into the space under your home at some point.
Drainage systems are designed to prevent just that. They collect excess water from the soil around them and move it away from your foundation to a spot where it won’t cause leaking or foundation damage.
French drains are some of the most popular exterior drains because they’re easy to install and usually work very well.
In this article, we will talk about how a French drain works, signs you need one, and a cost guide for installing one on your property. We’ll also offer some tips on how to save money on the installation.
Table of Contents
- What Is A French Drain?
- What Are The Four Kinds Of French Drains?
- What Are The Signs You Need A French Drain?
- Where Should A French Drain Be Installed?
- What Impacts the Installation Cost of a French Drain System?
- What Are The Costs Of French Drain Installation?
- How To Save Money When Installing a French Drain?
What Is A French Drain?
A French drain or drain tile is a system of perforated pipes that are set around your foundation. These drywells are covered by gravel to allow water in the soil to trickle down into the line.
The PVC pipes or corrugated drain pipes are angled such that water travels down and away from your foundation wall. The French drain will direct water to a catch basin where it can’t cause a problem for your concrete block walls.
French drains can also be installed inside your home as an interior drainage system.
This setup is less of a proactive fix to water intrusion and instead takes water out of your basement or crawlspace after it has already gotten in.
What Are The Four Kinds Of French Drains?
There are four different types of French drain systems that you can use as part of your basement waterproofing system.
Each kind is put in differently to fix a specific water problem. We will discuss the four different types and their uses.
Interior French Drain
French drains can be installed in the concrete slab around the perimeter of your basement walls. Drainage systems installed inside are called “weeping tiles” and are meant to remove water that makes its way through your concrete.
They are good solutions for homeowners who battle a wet basement frequently.
These interior drains are usually very costly because a professional must carefully excavate concrete from your slab.
They usually get used with a sump pump and can remove quite a lot of water that seeps in, so they’re a good fit for homeowners who have regular water seepage.
Exterior French Drain
Exterior French drains are often called “curtain drains” or “perimeter drains” and are set in the ground just outside your foundation walls.
They are meant to remove water from your topsoil before it makes its way inside your home, so they are a more proactive solution to water intrusion.
They use gravel to port water into your piping and landscape fabric to stop clogs from plant growth.
These drainage systems excel at relocating runoff from heavy rain or groundwater away from your house. We’ll review the two different kinds of exterior French drains and what each is best suited for below.
Shallow French Drain
Shallow French drains get set about a foot or two under the surface outside your basement walls. They require little excavation, so they are the cheapest of all the French drain types. They can be done as DIY projects by handy homeowners to make the installation even more affordable.
Shallow drainage systems are best at removing runoff because they’re so close to the surface. They won’t remove enough groundwater from below your foundation to make them practical for that purpose, but they excel at protecting your concrete from surface water.
These drains are more likely to collapse or be damaged than deeper set drains. They can also be seen from the surface and will change the aesthetic of your yard.
Footing Drain
Footing French drains are set deeper than shallow drains. More excavation is required to get them down to the level of or below your foundation footings. They sometimes are placed 8-10 feet below ground level.
Their placement makes them much more expensive and harder to install unless they are set during construction.
They won’t do much to protect your foundation from surface water, but they are great for protecting your home from groundwater. These are the drains often used if you have a high water table on your property.
Footing drains can be damaged during backfilling but usually don’t collapse as easily as shallow drains once they’re installed. They also aren’t visible from the surface.
What Are The Signs You Need A French Drain?
Your foundation and property will often signal that some kind of drainage system is needed. Each drain is ideal for specific problems, so there are different signs that indicate you should install one over the others.
Regular water damage, standing water, or frequent leaks inside your basement or crawlspace are signs that an interior French drain might be needed.
Drainage problems on the outside of your foundation can sometimes be seen from the surface. You may notice water collecting on the surface during rainfall and forming puddles on your lawn or patio.
These are signs that a shallow French drain would be most useful.
Groundwater can be harder to detect, but if you notice water seepage that isn’t correlated with precipitation, you may have a groundwater problem.
Where Should A French Drain Be Installed?
Of course, the placement of French drains will depend on which type you’re installing. We also have an entire article about why french drains aren’t always a good option. However, if you’ve decided on a french drain for your home, let’s discuss some best practices for the different kinds of drainage systems below.
Slopes Or Low Points
Rainwater or other runoff will always follow the slope of the land to some extent. It’s best to slope soil away from your foundation to begin drainage naturally.
Shallow French drains are regularly installed around entire foundations but can also just be placed at low points of your property near the concrete walls.
It’s never recommended for land to slope downhill toward your concrete, but sometimes the land dictates what is and isn’t possible during construction.
A French drain will be effective at the lowest point near your foundation if you have a slope leading down to your home.
Perimeter Of Your Foundation
As I mentioned above, many homeowners choose to install shallow French drains around the entire outside of their foundations.
This option offers the best protection from rainwater. Footing French drains are almost always installed around the whole perimeter of the home because groundwater is often level and will affect your entire foundation.
Basement Floor
Lastly, interior French drains can be set into your basement floor. They’re installed around the interior perimeter of your basement or crawlspace and are very useful for routing any water seepage to a sump pump for removal.
What Impacts the Installation Cost of a French Drain System?
The cost to install a French drain depends on numerous factors, and each can have a big impact on the total cost. We’ll discuss some of the factors that can affect the pricing most below.
Trenches
Excavation is one of the most significant cost factors related to any foundation work. You need irrigation ditches dug and angled correctly before you can set the drainage system in place.
A trencher or backhoe can make quick work of the job but will be expensive to rent. Having the trenches dug manually can be even more costly but may be necessary if you have utility lines or other obstructions.
Excavating for footing drains is the most expensive because of how deep the drain pipes need to be set.
Shallow drains and interior drainage pipes require costly excavation too, and they can incur costs between $100 and $200 per linear foot before any equipment is ever put in place.
Accessibility
Another factor that will add to the cost of excavating is how easy it is to get to the areas where your drain pipes will be placed.
Exterior drains are made more expensive if patios, decks, driveways, landscaping, or other large structures need to be removed. Interior drain areas are more difficult to access and are more expensive if you have a finished basement.
Soil Content
The quality and type of your soil can affect the ease of excavation too. Expansive clay can be more dangerous to backfill, while slate and shale will make excavation harder. These soil types will increase the total cost of your project.
What Are The Costs Of French Drain Installation?
The national average cost to install a French drain is typically between $2,000 and $15,000. Your particular price will depend on the type of drain and the difficulty of excavation.
An interior French drain usually costs around $60 per linear foot. The total cost for a 1,200 square foot basement will average $13,500. You can expect to add about $1,000 to the price for each sump pump that needs to be installed.
Shallow French drains on the outside of your foundation will cost up to $15 per linear foot or a total of about $4,000 for a 1,200 square foot house.
Footing drains are the most labor-intensive and the most expensive. They average around $100 per linear foot and will total about $25,000 for a 1,200 square foot house.
Larger homes, soil content, obstructed excavation sites, and other difficulties with installation will increase each system’s cost.
How To Save Money When Installing a French Drain?
There are a few ways you can bring down the total project cost of a French drain system.
The best way to save money on the installation is to get the system that is the best fit for your property. You can spend a total of close to $50,000 to get all of these drain types installed, but choosing the one that solves your problem will cost significantly less.
For example, you can spend $4,000 on a shallow drain, but you’ll end up spending an additional $25,000 if your root cause of water intrusion is groundwater because a footing drain is more appropriate. Get the proper solution for your situation to save money in the long run.
Additionally, hiring one of our professionals to do the work and a landscaper to restore your property can be expensive.
You can save money on labor costs if you can do the job yourself. I strongly recommend against attempting footing drain or interior drain installation. However, a shallow French drain can be a good DIY home improvement project and will just cost the price of materials.
Lastly, fixing the root cause of your leaky basement will go a long way in limiting how much you need to rely on a French drain.
Installing gutters and downspouts and grading your dirt away from your foundation will help reduce your leaking problems with or without a French drain installed.
